SECT. I.
I. There is so great a latitude in scepticism, and its gradations are so different, that according to the various extension that is given to the meaning of the word, it is used to describe the most extravagant error, and the most prudent mode of philosophizing. Rigid scepticism is a wild delirium, moderate is prudent caution. But those who in this age, have undertaken to combat the moderate sceptics, have either from ignorance or malice, confounded them with the rigid. When I reflect how gross a thing ignorance must be in such a case, it makes me think they acted from malice, and when I consider how detestable a thing malice is, it makes me conclude what they did was through ignorance.
II. Although the Greek word scepsis, from whence sceptic and scepticism are derived, signifies inquisition, investigation, and speculation, custom has in a great measure altered the meaning of the term; on which account, sceptical at this day, implies doubt, or doubting; and scepticism, that particular avowal which sceptics make of doubting, or withholding their assent to all matters, that are liable to be controverted or disputed.
III. This doubt or suspension of assent, may be more or less rational, in proportion to the greater or less extent that is given to it, or according to the matters to which it relates. Thus, although doubting of many things would be prudence, doubting of all would be madness.
SECT. II.
IV. And although authors commonly represent to us, some subtil philosophers of antiquity, as obstinately persisting in suspending their assent to every thing that was proposed to them, and which was evident both to their reason, and their senses, and likewise represent them, as earned defenders of universal scepticism, to which opinion they refuse to admit of the least exception; yet for all this, it is very doubtful to me, whether these were their real sentiments; and I am rather inclined to think, they did it, to shew their ingenuity, and to display their talent for disputing; or that from some other motive, they spoke differently from what they thought. The most famous among this tribe, were Archesilaus, Carneades, and Pyrrho. But the first, if we believe Sextus Empericus, was in reality a Platonist, and only a sceptic in appearance; whose method it was, always to dispute problematically upon every thing in public, but was ever careful to suggest in private, to such of his disciples as he found were the most capable, the Platonic doctrine. Cicero says, that his zeal for contesting every thing that was advanced by his school-fellow and rival Zeno, carried him to the dangerous extreme, of endeavouring, although it was against the conviction of his own mind, to refute whatever was advanced by Zeno. We may add to this, that according to the testimony of Diogenes Laertius, Archesilaus never went to the extreme of doubting the evidence of his senses, but rather treated with contempt and derision, those who carried scepticism to that length.
V. Carneades was a most subtil philosopher, and so eminent as an orator, that Cicero in various parts of his works speaks of him with admiration and envy; and assures us, that by the keenness of his ingenuity, and the fertile torrent of his elocution, he could persuade his hearers to believe whatever he thought fit, and Quintilian, and Numenius, declare the same; and it is probable, that his propensity for disputation, and his ambition of shewing his ingenuity, excited him to contest the most established axioms; which together with his affecting to distrust the evidence of his senses, made him pass for a rigorous sceptic. But we may venture to assert, that if an historical anecdote which is related of him by Numenius is to be credited, Carneades believed his eyes as much as any man living; for having surprized a concubine of his in the embraces of his beloved disciple Mentor, he was so offended at his treachery, that he broke with him for ever, and excluded him from being the successor to his academy. How happened it then, that like a good sceptic, he did not doubt whether the representation of that obscenity, might not be a deceptio visus? I for my own part am inclined to think, that there never yet was a sceptic in the world, who after the exhibition of such evidence, could maintain his heart and his mind in a state of suspence.
VI. It is commonly said of Pyrrho, who was by so much the most famous of all the sceptics, that he in a manner obscured the others, by giving his name to the system of universal doubt, which at this day is called Pyrrhonism, and the sectaries of it Pyrrhonists; and he was so positive in maintaining, that we should suspend our opinion, with respect to all we saw, or felt, that he would not turn the least aside, to avoid being run over by a mad horse, or bit by a mad dog; nor would he slacken his pace, although he was warned that he was advancing near the edge of a precipice; and that he would have perished a thousand times by these dangers, if his friends, who were attentive to his safety, had not prevented his running headlong into them. But although this account of him is much vulgarized, I do not know whether any other antient author, except Antigonus Carystius, a Greek historian, who was contemporary with, or lived very nearly in the days of Pyrrho, has vouched the truth of it; at least the learned La Mothe de la Vayer, quotes him as the only author, who attests the relation; and it is even doubtful whether Antigonus Carystius asserts the thing positively, because in the Præparat. Evang. lib. 14. cap. 18. of Eusebius, we find this author quoted for a fact, which contradicts that relation; which is, that Pyrrho, when a dog was once about to run at him, climbed up a tree to get out of his way, and avoid the danger. Upon which occasion, those who were present, raillied him upon the difference there was between his doctrine and his practice.
VII. But let Antigonus Carystius, who is an author I have not seen, or any other whatever, say what they will, to give sanction to this relation, we may without the apprehension of being accused of injustice, condemn as incredible, the account of Pyrrho’s having carried his extravagance to such a length. This philosopher lived to the age of ninety, and through the whole course of so long a life, it is not probable, he should always have friends at his elbow, ready to save him from the many dangers, to which a man of so rash a conduct must unavoidably have been very frequently exposed, and especially, in the long voyage he made to India to consult the Gymnosophists. Diogenes Laertius, who is the person that gives us the account of the great age to which Pyrrho lived, and of his voyage to India, assures us, that Pyrrho led a very solitary and retired life, which is not very compatible with his having always been attended by his friends, nor is it reasonable to conclude, that a man who was so very ridiculous as he is described to have been, could have very many, or very sincere ones. Finally, the citizens of Elis, his countrymen, elected him the high priest of their religion. Now how is it credible, that they should have confided such an employment to a person, who if his scepticism had been carried to the length we have mentioned, they must certainly have looked upon as a mad man? From this circumstance, it may also be inferred, that the charge of impiety, which was generally imputed to him, was an unjust one; because his countrymen would hardly have elected him the supreme minister of their religion, if they had known that he professed to be of no religion at all, and that he doubted the existence of a deity. What devotion or zeal could they expect for the service of the temple, from a man, who either was ignorant of, or doubted whether the object of their worship existed?
SECT. III.
VIII. I not only think, that these philosophers did not in their hearts, adopt the system of universal doubt; but I also believe, there never was any one who sincerely did it; because there are objects, with respect to which, there can be no doubt but by implication. No one, for example, can doubt of his own existence. The very act of doubting, is affirmative of a certain knowledge, because he who doubts, must certainly be convinced that he does doubt; and if the sceptics are not certain that they doubt, how can they affirm they do with such obstinacy and stiffness? Therefore we should conclude, that it is not from sentiment, but from their fondness for disputation, that some of them defend the system of universal scepticism; and if there ever was any one who truly assented to it, we should not consider him as a philosopher, but as a lunatic; for it would be improper to call maintaining such a system, a particular mode of philosophizing, as we ought with more justice, to term it a particular mode of raving.
IX. It is most likely then, that the most rigid sceptics, and those who were truly and bona fide such, admitted of some exceptions to the universality of their system, or understood it in some determined sense, which limited or restrained it. Socrates, whom some look upon as the primitive father of the sceptics, said of himself, that he knew nothing with certainty, except it was his ignorance of all things. This however, was placing some sort of limitation to the system, although it was but a very small one. But I am of opinion, that Socrates, who was a very modest man, only meant to say, that what he knew amounted to but a small matter, and that therefore we ought to understand his declaring himself totally ignorant, as an hyperbolical expression. Saint Justin the martyr, and other fathers who highly applauded that philosopher, would not have done it, if they had taken him for a rigid sceptic, which would have amounted to the same, as his having been an impious man; because it is evident, that he who doubts of every thing, cannot be a person of any religious principles; but he was so far from such a kind of man, that it is most probable, the Athenians condemned him to death, because he affirmed the existence of one only God. It is at least certain, that he treated the multifarious number of the heathen gods with great derision; from whence we should conclude, that he knew this important truth, that the Godhead admits of no multiplication.
X. Other sceptics, who said that they doubted of every thing, and that we ought to doubt of every thing, did not perhaps mean to exclude all certainty, but only scientific and demonstrative certainty, which except in mathematical cases, we must confess is very rare to be found. Even many mathematical demonstrations, and especially those which are very complicated, are not exempt from the suspicion, of there being some occult fallacy contained in them, on which account they ceased to be true demonstrations. How many have presumed to demonstrate they could square the circle, whose modes of doing it, and their reasonings upon the subject, when they came to be submitted to rigorous examination, have been found to have some sophism involved in them, or to have been built upon some supposition which was taken for certain, when in reality it was not so. The geometrical demonstrations, with which they prove the infinite divisibility of the continued quantity, are sufficiently simple; notwithstanding which, there are authors, who because the infinite divisibility of the quantity is imperceptible, suspect, that there is some occult sophistry involved in those demonstrations.
XI. Others have refused to credit the evidence of their senses; but not so grossly, but that they have condescended to make use of them to direct their actions in the common affairs of civil and human life. They govern themselves by them for the purpose of living, but not for that of philosophizing. The information of their senses serves them to chuse the useful, and avoid the pernicious, but not to determine the theory of an object.
XII. The arguments they assign for this distrust of their senses in the last instance, may be reduced to three. The first is, the distinction we should admit between the impression which objects make on our senses, and the absolute essence or quality contained in the objects themselves. For example, we say that hemlock is bitter. If by this expression, we mean to declare, that this herb makes on our palate a determined impression or sensation, which we call bitterness, we speak properly; but if we mean to say that the herb in itself contains an absolute quality, which we describe by the same name, we speak improperly; for if this was the case, all the animals who relish hemlock would find it bitter; but it happens otherwise, for the goats are fond of it, and eat it greedily. In the same manner do all those reason, who adopt this mode of arguing with respect to all other sensible species. They say, the fire produces in us that kind of impression, which we call heat; but that we ought not from thence to conclude, that it is hot in itself. Thus although by approaching very near to it, it produces pain in us, still it is not sensible of any itself. Therefore we ought not for this reason, to say the fire contains pain, it being at most only capable of occasioning pain; neither ought we to call it hot, but only capable of producing heat; nor can we call it hot but by equivocation, as we say, Medicine is healthy, because it produces health in the animal.
XIII. This distinction is the fundamental maxim, by which the modern philosophers maintain their rejection of all the sensible qualities, which are assigned by Aristotle and his followers to objects; and they carry the matter so far, that they will positively assert to you, that neither snow is white, nor charcoal black, nor a bell sonorous, nor a flower fragrant; and if you mean to express by these denominations, intrinsic qualities, or such as proceed from some accidental intrinsic form contained in objects; they will not allow such descriptions of things to be good and valid, but only so far as they signify certain determined impressions, which by means of the physical and corporeal impulse of the insensible particles of matter, are made on our organs, which are of the same use to us, to enable us to chuse the good, and avoid the pernicious, as our knowledge of the real intrinsic forms would be. They proceed to assert, that men would equally abstain from eating arsenic, if they believed the moderns, who say this mineral kills by dissolving the blood, by the rapid motion of its particles; as they would by believing Aristotle, who imputes all the mischief it occasions to be the effect of a venomous quality existing in the arsenic, and that they would be equally anxious to acquire gold, by believing the moderns, who say its brilliant yellow hue is the effect of a determined impression made by the light on the retina, where it appears reflected in that colour, from the particular texture of the insensible particles of the gold, as they would, by believing Aristotle, who says, the colour proceeds from an accidental form, inherent in the gold itself. I know very well, that a learned philosopher said, a little while ago, that the ladies had great reason to complain of Descartes, for having taken from their faces that delicate smooth whiteness which makes them look so tempting, and for having placed it in their admirer’s eyes. But although this may do very well as a joke, it is certain, that the charm has an equal effect to make them appear desirable, whether it is stamped on the eyes, by the particular reflection, which, by the determined texture of the insensible particles of the skin, is made by the light, or whether it is produced by the intrinsic quality, which the Aristotelicans assign as the cause of colours; and I much doubt, whether to this day, the Carthesian philosophy has served any man as a preservative, against the venom of that sweet poison, which we call beauty.
SECT. IV.
XIV. The second reason assigned for distrusting the evidence of our senses, is the experience we have of the alterations which are produced on sensible species, either by the interposition of a medium, or the different dispositions of our organs. The species, which by passing through a uniform, or homogeneous medium, appears straight, by being passed through a different one, will seem crooked, as may be evinced by passing a straight wand from the air through water, which, by virtue of the refraction of rays produced in its passage from one element to the other, will make it appear crooked. To him who has a jaundice, every thing he looks at seems yellow; and although it is true, that this is the effect of a preternatural accident, we are not certain, whether abstracted from all morbific dispositions, there are not in various individuals, different temperaments and configuration of parts, which are capable of producing different sensations with respect to the same object; and it seems most probable, from all that is evident and manifest to our observation and experience, that the thing is so, for we don’t see any one individual, who is perfectly and exactly like another; and we have known men, whose right eyes have represented objects, both with respect to colour and magnitude, different from their left.
SECT. V.
XV. The third ground for the said distrust, is derived from the erroneous representation of things made by the imaginary faculty, which fancies external sensations of objects that do not exist. Such, for example, as the imagination of him who has had a leg cut off, representing to him a pain in the leg or foot that has been amputated; or that of an hypocondriac person, who fancies himself to be glass, earthen ware, a wolf, or a dog, whose imagination represents those strange forms, as evidently and manifestly palpable to his senses; so that he who fancies himself glass, will swear with invincible firmness, that he perceives in his own person the transparency, and feels on his own skin the smooth surface, which is proper and peculiar to that artificial composition.
XVI. This error is common to all men in their wanderings when they are asleep; because he who dreams, believes he perceives those objects with his senses, which he only perceives with his imagination; and from hence, the rigid sceptics deduce a most pernicious argument, by way of proving, that we should doubt of every thing; because they say no man can be positively certain, whether he is asleep or awake; according to which mode of reasoning, no one can be certain, whether he sees, hears, or touches any thing whatever; for notwithstanding his having the greatest confidence that he is awake, it is possible that he may be sleeping; and that the things which are represented to him as seen, heard, &c. are all imaginary. For example, I consider myself as now writing, and reading what I write. But what certainty have I that I am writing and reading? Have not I dreamed a thousand times, that I was reading and writing? And at those times, such occupations appeared to me, not as things that I was dreaming of, but as exercises that I was really and actually practising; and therefore, that may be the case with me at present.
XVII. I have said already, and with reason, that this argument is a most pernicious and dangerous one; for whatever answer you make to it, your adversary turns upon you, and urges the opposite opinion as forcibly, as you can support your reply. At least I have never seen any solution of this matter, which could more or less vanquish the force of the difficulty. It has been objected to this sort of reasoning, that the argument proves too much, and tends to involve in, and reduce to the same state of doubt, all the sacred dogmas of religion. This remark is a just one, for he who comes to doubt, whether all he hears or sees is not a mere imaginary representation, must necessarily doubt of the reality of all the instruction he has received, both with respect to religion, and every other matter. But what advantage shall we gain, by insisting upon this against a sceptic, whose intention perhaps is to destroy all religion? And although he should not argue with this depraved view, but should reply to these objections out of wantonness, or from motives of vanity and ostentation, and a fondness of shewing his parts, it would be wasting time to dispute with him, or to press the argument, because these instances, notwithstanding they are good ones and may be fairly insisted on, are not answers.
XVIII. It is certain there are some truths, that maugre the clearness and confidence with which the understanding assents to them, are not exempt from being exposed to difficult objections; or to speak more properly, there is no truth whatever, be it ever so firmly established, against which, some sophistical objection may not be raised. It would therefore not be right upon all occasions, to give up a maxim, whose truth we clearly perceive and are convinced of, only because we can’t reply to every argument that may be urged against it. There are truths of such a nature, that although they would strike, and be clear to any man of ordinary understanding, still, the giving an answer to every objection that could be raised against them, might possibly be found a difficult task to a person of very subtil ingenuity. And notwithstanding we should not be able to hit upon an argument, that would confront or silence those which are used by the sceptics, to persuade us to doubt whether we are sleeping or waking, we should not abandon ourselves to such a doubt, but support ourselves in a firm confidence, that we are not mistaken with respect to the state we are in. And in truth, the arguments used to make us doubt of it, are not of such a nature, as that a clear, solid, and unembarrassed answer may not be given to them.
XIX. And in order to do this, I shall begin with supposing, that evidence in this case may be of two sorts, mediate, and immediate. An evident proposition, supported by immediate evidence, is, when without the assistance of any kind of proof, it presents itself so clearly to our understandings, that the mind is constrained by invincible necessity to assent to it. An evident proposition supported by mediate evidence, is, when of itself, it is not represented to our understandings with all this clearness, but is necessarily inferred from some other self-evident proposition.
XX. I will suppose, secondly, that immediate evidence should be divided, into metaphysical and experimental. The first is governed by universal principles, which of themselves persuade or convince the understanding; such as these, the whole is greater than a part; two contradictory propositions can’t be both true at one and the same time. Experimental evidence is derived from certain singular truths, which strike every individual with infallible conviction; such as these, that I at present have such or such a desire, or that I think of such or such a thing, that I suffer some pain, or that I am affected with some particular sensation; for example, joy, sadness, or anger.
XXI. That every individual feels this experimental evidence in some particular instances, no one can doubt, and even if any person, by giving to his scepticism all imaginable extension, should be desirous of doubting of every thing, he could never stifle the experimental evidence that he doubted. And here I can’t help remarking, that experimental evidence is a thing of such moment to the Carthesians, that all their metaphysical testimonies depend on, or are derived from it; because, from that first maxim or proposition, I think, is inferred immediately, the proof of their own existence; and mediately, all the other demonstrable truths, are established upon experimental evidence only.
XXII. It is also certain, that from the truths which are established upon experimental evidence, you can deduce no demonstrative reasoning; or at least of that sort, which the logicians call à priori. The reason is, because they are evident of themselves, or else are supported by immediate evidence, and are not dependant upon any other thing from whence they are inferred. Therefore, although for example, I at present am convinced that I am desirous of eating such or such a thing, I cannot persuade any other person that I fancy it, by any immediate demonstration; because this is evident to me, not from any principle that is notorious to all mankind, and from whence may be inferred the existence of such a desire; but because the appetite itself, is intimately connected with my spirit, and I feel it so forcibly, that I cannot doubt of its existence: the same thing happens in the cases of those truths, which are established upon immediate metaphysical evidence. If I should be asked, how I know that the whole is greater than one of its parts, I should answer, that I do not know it from any principle from whence it may be inferred, but because the truth, that the whole is larger than a part, is so clearly evident to my mind, that it is as incompatible with doubt, as the light of the sun with midnight darkness. If any one should deny to me, the truth of the maxim, that two contradictory propositions cannot be both true at the same time, it would be impossible for me to prove the truth of the maxim, either by arguments deduced à priori, or à posteriori. The reason is plain, because if I was to argue the point, the most I could do, would be insisting on the manifest contradiction, and asserting the impossibility of the thing, which is the last resource of logical dialect. But observe, when we are got thus far, my adversary, to act consistently with his first caprice, thinks fit to change his ground, and to admit both extremes of the contradiction, and to insist they are both true. Now how, in this case, am I to prove that they cannot be so? Why I can do it by no other means, than by having recourse to the axiom, that it is impossible two contradictory propositions can be both true at the same time. But this is begging the question from the beginning, and proving what is denied, by the same proposition which is the subject of the dispute.
XXIII. The suppositions we have just made, contain all the solutions we are capable of giving, to the above argument. I say then, that I myself, and I say the same of all others, who are in my present situation and circumstances, have experimental Evidence that I am now awake: because the state of wakefulness, which consists, in the intimate and ultimate disposition of the faculties to exercise themselves in proper operations, is an object, which presents itself to my mind, with such clearness, that if I was never so desirous of doing it, I cannot entertain a doubt of my being at present in that state; nor can any other reason be required of me, nor can I give any other, for assenting to this truth; neither can I for my assent to a first principle, give any other than the beforementioned, nor alledge any other, to explain the existence of any reflection, which my soul is at present intent upon.
XXIV. I will not however dissemble, that after this answer is given, there still remains a serious difficulty to surmount, which may be stated in the following manner. The experimental evidence, from whence we deduce this persuasion, is fallacious; because when we sleep and dream, we are under the same persuasion that we are awake, and our senses then represent to us, that we are engaged in actual exercises in such a manner, that if it was at that time to occur to us, to make reflection upon what we were doing, we should conceive, that we had experimental evidence of our speaking, seeing, hearing, &c. Therefore the idea that I now entertain upon reflection, that I have at present experimental evidence of my being at this instant awake, and engaged in study and writing, affords me no absolute certainty that I am not asleep, or that I am actually so employed.
XXV. This is the utmost extent to which the matter of doubting can be carried. But by way of answer to it, I shall reply, that the persuasion we have of being awake when we are dreaming, differs greatly from that we have of being awake, when we actually are so. This last is a clear, firm, determined, invincible persuasion, and such a one, as is required to constitute experimental evidence of the certainty of the fact; which it does in such a manner, that notwithstanding all the reflections we can make, and all the doubts and difficulties we can suggest, our assent to, and persuasion of the truth of it, remains firm and unshaken. On the contrary, when we are dreaming, our reflection is obscure, and the persuasion produced in consequence of it, feeble and wavering; which will evidently appear to be the case, if in the course of our dreaming, it should occur to us to make a doubtful reflection, whether what our imagination represents to us is reality, or only a dream; and the result to a man who was to do this would be, a faint and doubtful determination of whether he actually dreams, or only believes he is dreaming, and he would remain in a state of doubt, whether what his fancy represents to him be real or not. I say in all these cases, his decision of the matter, would not be resolute and firm, but wavering and languid. This doubt of whether I am asleep or not, often occurs to me in dreams, which never fails to produce one of the two following effects, either to certify to me that I am dreaming, or to make me suspend my assent to the fact. And I will venture to assure any one, who shall persist for a few moments, in proposing these doubts to himself when he is dreaming, that he will find the same thing happen to him.
XXVI. We may make use of the same reasoning, if the argument is applied to the deliriums of maniacs. Every man, who after having been deprived of his reason, comes to be restored to his senses, finds a great difference with respect to the persuasions he feels, and the clearness of the opinions he forms in a state of sanity, and those he entertained when he was mad. Mad people seldom make any reflections, either on the state of their mind, or the subject of their madness; and when they do happen to make them, are generally more or less blinded by their apprehensions; of which I myself have known some instances; and it has fallen in my way, by the force of lively representations, first to prevail on some mad people to doubt of the truth of their apprehensions, and afterwards to reason them out of them; among whom there was a nun, who had been exceedingly mad for some years, and whose life was thought to be in danger, although in reality it was not so; and I being called to administer the sacraments to her, was so happy as to reduce her mind to a state of calmness, that rendered her capable of receiving them as a penitent. This I accomplished, by using various reasonings and arguments, tending to undeceive her, and at last was so fortunate as to hit upon one, adapted to the nature of her disease, and the state of her mind, which had its effect: but in doing this, great attention should be had to the tone of the voice, and the energy and vivacity of the looks, and care should be taken, that every action should be such, as is likely to give efficacy and force to the arguments you use, in order that they should make an impression on their minds; great caution should also be used not to irritate them; and by these means, they are often brought to intervals of sense; and although it is true, that they seldom last long, still the gaining an hour of calm reason, is a matter of great importance, as it was in the case of the nun we have just mentioned.
XXVII. The delicacy and curiosity of this subject, has caused me to dwell on it longer than was necessary; for I am so far from apprehending, that the arguments which are used in support of universal scepticism, will prevail with, or have any weight on the world in general, that I do not believe there ever yet was a man, who in reality was convinced by them.
SECT. VI.
XXVIII. The limitations with which rigid scepticism may be mitigated, are innumerable; consequently, scepticism will appear more or less absurd, according to the various exceptions with which it is corrected; but this is a matter of such extent, that to reason upon it with any degree of precision would fill a large volume. I shall therefore proceed to treat of scepticism, as confined within the line of physics, which is the point, to which I proposed at first to restrain my arguments on this subject.
SECT. VII.
XXIX. I have always wondered, and do not yet cease to wonder, at seeing modern philosophers attack scepticism as a physical error, and am much astonished, to find them condemn it in that sense as an error, dangerous to the dogmas of faith. Nor can I comprehend, how such a charge can arise, otherwise, than from gross ignorance or malicious spite; unless it is applied to some sceptic, who from explaining himself loosely, may have given occasion for such an imputation.
XXX. The system of physical scepticism, asserts, that physical and natural things, do not admit of demonstration or scientific certainty, but that they are all matter of opinion; and consequently, that we should not call natural philosophy a science, because strictly speaking it is not one, but rather a habit, or acquired facility, of reasoning with probability upon natural things. We shall understand science in this place, in the sense which Aristotle and the schoolmen understand it, who define it, to be an evident knowledge of the effect by the cause. But in our definitions, we shall not exclude experimental certainty, or certain knowledge, acquired by the experience we have had, and the observations we have made, of physical matters; but we shall rather maintain it, as the only method by which we can arrive at attaining truth; although I doubt whether we shall ever attain by it, a discovery of the internal, or intimate nature of things.
XXXI. Neither will we deny, that with respect to physical objects, many propositions may be advanced or supported, which are deducible with infallible certainty from metaphysical principles: as for example from this, the whole is greater than its part, is evidently inferred, that a man is bigger than his head; and from this, being is the effect of operation, is inferred, that my father existed when he begot me. But these, and other innumerable demonstrations of this sort, afford no physical knowledge whatever; because they do not manifest in any degree, either great or small, the nature of the very entities which are the objects of them. Why do I say manifest the nature of the entities? They do not even display to the understanding, a single truth, which may not be comprehended without their help, by the most rustic man upon earth. So that the syllogistical conclusions upon infallible truths, which the school philosophers so much boast of, do nothing more, than explain by circumlocution and in terms of art, the very things, which may be immediately comprehended, and naturally explained, by any rational man who never studied. Further, how can they call by the name of demonstrations, things which demonstrate nothing? that is, they manifest nothing, but what was manifest without their assistance. A logician will say, thinking he says something to the purpose, that he knows by means of the art of demonstration, that which he could not know artificially without this aid. But I answer, that this artificial knowledge is totally useless, because it neither manifests to me any one truth of which I was before ignorant, nor does it illustrate to me with greater clearness, the things I was before acquainted with; it being certain, that it is as evident and clear to the rustic, and that he assents with as much firmness, that the whole tree is bigger than one of its branches, without the help of artificial logic, as I do, assisted with my whole armory of syllogisms. If a learned person, should undertake to instruct a man who walks well, and with a good grace, by explaining to him all the laws of motion, to step scientifically; and also, by explaining to him the number and use of the muscles, should teach him the application of those laws to every member of his body concerned in that exercise; should not we be apt to say, that besides his taking a very tedious one, he had also taken a very needless trouble, it being certain, that his pupil, after all this pains, would not walk a jot better, if so well as he did before; the cases are similar.
SECT. VIII.
XXXII. The thing then being understood, in the sense we have explained it, the conclusion I draw from the premises is, that science, or scientific certainty is not to be found in physics. Doctor Martinez, in the second volume of his Medicina Sceptica, (Convers. 27.) proves this conclusion abundantly, both by the authority of scripture, and by the sentences of many fathers; though as the works of this author are easily to be met with, I shall not here insert the authorities he quotes, but shall content myself with adding to them two very remarkable ones that he has omitted. The first is, that of my father St. Bernard (in Cant. Cantic. Serm. XXXIII.), who when he is speaking of philosophers, says, Vagi sunt, nulla stabiles certitudine veritatis, semper discentes, et nunquam ad scientiam veritatis pervenientes. And it is somewhat remarkable, that the Saint says further, philosophers never arrive at attaining a certain knowledge of the very truths they themselves are in search of, and are desirous of teaching to other people: semper discentes; and lest some should conclude he spoke of supernatural truths, I thought it necessary to hint here, that these are not the objects of philosophical inquiries. Neither should we suppose, that he spoke of the moral philosophers, because many of these, even including the Gentiles, investigated many truths, that came within the compass of their plan, with intire certainty; and it is evident, that if Aristotle, had written with as much precision upon physics, as he did upon ethics, we needed not to have wished for any thing better.
XXXIII. The second authority, is that of Lactantius Firmianus, an illustrious person, and a venerable member of the church; this great man (Lib. III. Divin. Instit. Cap. iv. v. and vi.) treats largely of the scepticism of Archesilaus, of whom we have spoken before, and after combating and confronting this philosopher effectually on the subject of universal doubt, admits without reserve, that he would have been right, if he had limited his scepticism to matters of physics, because there is not, nor ever can be any science, which will teach mankind, the causes and reasons of natural things: Quanto faceret sapientius, ac verius, si exceptione facta diceret causas, rationesque duntaxat rerum cælestium, seu naturalium, quia sunt abditæ, nec sciri posse, quia nullus doceat, nec quæri opportere, quia inveniri quærendo non possunt.
XXXIV. Some of the sceptics themselves prove our conclusion, for they say, that the things appertaining to physics are singular, and that from singular things you cannot derive a science. But this reason does not satisfy me. In the first place, notwithstanding physical things are for the most part singular, they in some instances may cease to be singular. Thus, although every real entity is singular, it may, contemplated metaphysically, depart from its singularity. In fact, the schoolmen together with St. Thomas say, that physics may depart or be separated from their singular, but not from their sensible nature; and that mathematical things, may depart or be separated from their singular and sensible, but not from their intelligible nature; also, that metaphysical ones, may depart or be separated from their singular, sensible, and intelligible. In the next place, the axiom that from singular things you can derive no science, should be understood with some grains of allowance; that is, of such singular things as are particularly necessary to the individual, and are accidental to the species; but from those which appertain or belong to the species, science may be deduced, even when they are connected with the individual. For example. If I know scientifically; that man according to the general received opinion respecting him, is risible, I also know scientifically that Peter is risible, for in the following syllogism; every man is risible; Peter is a man; and therefore Peter is risible, is implied the truth of the premises, and the consequence deducible from it is, that it is scientifically evident. Further, if ever a philosopher should arise, who should know with certainty, the specific nature of all material entities, and from that knowledge, should be able to demonstrate all their properties, and the respective operations appertaining to each species, and in virtue of this extraordinary penetration, should be capable of giving reasons à priori for all the phenomena of nature, we should not be able to deny, that such a philosopher possessed physical science, notwithstanding the object of his science, related only to the species, unconnected with individuals. What then remains to be proved, is, that in physics there is to be found no sort of science, or evident knowledge of the matters appertaining merely to physics, abstracted from all other considerations; and truly the dogmatic naturalists, would be very happy, could they be permitted to possess a knowledge that amounts to as much as this; nor would it disturb them, to have it dinned in their ears, that the knowledge of common conceptions is metaphysical, and not physical; for they would tell you, that both physics, and metaphysics, may depart or be separated from their singularity, and that the principal distinction between them is, that the last regards its object with a greater degree of abstraction; that is, as exempt from all matter, and considers only those reasons, which may subsist abstracted from matter, such for example as spiritual entities; on the contrary, physics only contemplate material and corporeal entities; the most sublime of which conceptions, is that which regards the reason of the body, and the lowest, that which is attached to the corporeal part of it. But call this knowledge by what sort of name you will, either physical or metaphysical, the way to bring the matter to a short issue is, to shew that there is not in reality, any such knowledge.
XXXV. And what is more easy to be proved than this? I reason thus; physics contemplate the nature of an entity that has motion, or circulation; this may be considered, either according to the specific, or generative nature of the thing; and I assert, that nothing is known with certainty of the nature of any entity that has motion or circulation, either in one or the other of the before named senses.
XXXVI. And to begin with the specific, who can deny that in this sense, we know nothing of any one entity? I defy all the philosophers to tell me what is the constituent or component physical substance, of any one of the material entities that is to be found in the universe, and will give them leave to chuse that which they have most examined. St. Basil has some words (Epist. 168. ad Eunomium) that are admirably applicable to this purpose, and which I shall here insert: Itaque qui se existentium scientiam assequutum esse gloriatur, exponat nobis quomodo, quod minimum esse eorum, quæ in lucem prodierunt, natura habeat. Let the presumptuous philosopher, who boasts of his physical knowledge, explain to us the nature of the least entity which God has created. Let him, adds the same Father, who is ostentatiously vain of having penetrated into the secrets of nature, tell us what is the nature of an ant: Dicat formicarum nobis naturam, qui eorum, quæ in natura sunt scientiam cum fastu se prædicat assequutum. But why should we waste time? There is not, nor ever was to this day, any one, who by means of acquired science, could penetrate the constituent or component physical substance of any living or inanimate entity; the reach of our capacities not permitting us to go further, than to distinguish by some very extrinsic accidents, one thing from another; and this mode of distinguishing, is confined principally to those we call naturalists, and rarely extends to those in the schools, who acquire the appellation of philosophers, and who generally content themselves with distinguishing some few, which they commonly do in the unhappy manner we shall proceed to point out; but when school philosophers descend to treat of specific conceptions, their philosophy is so miserable and confined, that they only attempt to give the colour of a definition to a few species of brutes, whose voice they describe by some particular name, and then explain their conception of them, by some term derived from that name; thus they call the lion a roaring animal; the dog a barking one, and the horse a neighing one; but the fish, because they are very numerous, and are for the most part mute, cannot well be comprehended within this rule, and therefore are obliged to go without a definition.
XXXVII. The school philosophers cannot be ignorant, that these are not definitions, but should rather be termed mere shadows of definitions, which they make use of for want of true ones, to express logically, what definition is, what species, what gender, what difference, and other things appertaining to logical dialect; but is it not clear, that defining a horse by calling him a neighing animal, can give us no better conception of the creature, than may be conveyed to us by the most stupid clown, who would explain the thing more simply, and without school jargon, by telling us that a horse is an animal that neighs, or is capable of neighing? Oh! what a penetrating philosophical description is this of the nature of a horse!
XXXVIII. If any one, notwithstanding what has been said, should chuse to reply, that nature, as the root of all operations, should be explained according to the order, or habit of those operations; and thus, that a horse is well and physically defined, by the radical order of the act of neighing; if any one, I say, should reply to me in this manner; I apprise him in the first place, that all substantial nature has its absolute being, which is understood to be antecedent to the order of operations, for the first, is supposed to be the cause or reason of the other; that is to say, because such a thing has such a being in nature, from thence is derived the habit or aptness for such operations. I apprise him secondly, that if we should permit nature to be well defined by the precise or characteristic order of operation, this should not be extended to every sort of operation, but should be confined to the primary operation, which marks the foundation of the species; but alas, we are ignorant of what that is. For example, if a man, as is generally thought, is well defined by his rational faculty, or radical power of reasoning; because the being able to reason or reflect, is the principal, or primary operation of man; a horse then should be defined by his radical habit to that act of perception, instinct, or knowledge, which is proper to his species, and distinct from that of all other animals. But who has penetrated what this is? Or who has ever known the innate difference, that there is between the instinct of a horse and a dog? And thus, as it would be ridiculous and absurd to define a man by the radical order of elocution, by saying, that he is an animal who can talk and discourse; because this absurdity would be incurred, on account of the act of elocution being posterior, or secondary to that of reason or reflexion; and it would be much more ridiculous, to define him by the order of his voice, which you describe by some particular name, and to define him in the manner you define a horse, which you call a neighing animal; nor is it less absurd to define a horse by the radical order of his neighing. I apprise him thirdly, that if such definitions are admitted as good and legitimate, it is the most easy thing in the world, to define every substantial entity whatever, because in order to do it, you have only to observe its operations, give the most remarkable one a name, and define it by that name. By the help of this instruction only, you may make every peasant a consummate philosopher, and enable him to define the nature of all the entities in the universe.
SECT. IX.
XXXIX. These reflexions answer no other purpose, than that of confronting here and there a superficial and bastard schoolman, for all capable people know and confess, that we are unable to give a definition of any one substantial entity, except man. To what straight limits then is our philosophy confined!
XL. But the misfortune is, that we have no certainty, that the general received definition of a man, to wit, that he is a rational animal, is a good and unexceptionable one; for we are clear it would not be a good one, if this faculty appertains to other animals as well as him, and it is matter of doubt whether it does or not; but I will not, nor cannot, in support of this doubt, avail myself of the authority of Porphyrus, who in his Treatise on Predicables, supposes God to be a rational animal; and in order to distinguish between God and man, defines man to be a mortal rational animal, because he thought that without the addition of the word mortal, the definition would be applicable to God as well as man. Neither will I avail myself of the authority of Aristotle, from whose second book, De Sect. Pythagora, Jamblicus cites these words: Animalis rationalis aliud quidem est Deus, aliud autem homo. But I may for this purpose, avail myself of the authority of some Fathers, among whom is St. Austin, who all affirm, that the angels are corporeal, or at least have doubted of their incorporeality; to which doubt, appertains that, of whether angels are rational animals, for in order to suppose them so, there wants nothing but their being corporeal, and consequently it is doubtful, whether the definition of rational animal, appertains solely to man.
XLI. I may be told, that the corporeality of Angels has been condemned, and their incorporeality defined, in the second Council of Nice, and the fourth Lateran one. But in the first place, is it certain, that these Councils declared the incorporeality of angels to be undeniable, and that they declared affirming the contrary is erroneous; for it is somewhat doubtful, whether the incorporeality was defined in them or not; because, although mention was made in these Councils of this matter, it was not done with an express design to discuss the point, but was only touched upon, as we may say by incidence; which is an exception that all eminent theologians admit, to our being bound to observe things that are canvassed in that way even in Councils; as we are not obliged to suppose any matters defined in them, that are not debated and settled with an express intention. For which reason, the most learned Cano (lib. 5. de Considerat.) took the liberty of saying, that the opinion that angels were corporeal, although it might be false, was not heretical; and long before him, St. Thomas in his book de Malo, (quæst. 16. art. 1.) had said, that this question was no part of the Catholic Dogmas. My father Saint Bernard (lib. 5. de Considerat.) goes further; for he seems to think, the opinion which denies the corporeality of angels, to be void of probability; and it will not be improper to remark here, that he was much posterior to the second Council of Nice, and Saint Thomas, not only to the second Council of Nice, but to the fourth Lateran one also. This may likewise be alledged as an answer, to the objections that are made in consequence of some texts of Scripture, which give the epithet of spirits to the angels; for it is certain, that the fathers who considered it as defensible to maintain the corporeality of angels, were not ignorant of those texts; the exposition of which, in truth is not difficult, for we may fairly conclude, the Scripture calls them by this name, on account of their being airy or light bodies, and we may also suppose, that it is for this reason, that in various places it gives the name of spirit to the air. Spiritus procellarum. Advenientis spiritus vehementis, &c.
XLII. The second reply I shall make, is, that supposing it to be determined that the angels are incorporeal, this truth is not established by philosophy, but by faith; and as upon the knowledge of this truth, depends the certainty, that the definition of a rational animal does not belong to an angel; it follows, that by the help of philosophy alone, we should never have hit upon giving a definition of a man; and with respect to defining other things besides a man, its insufficiency is admitted. What sort of philosophy is this? It ought rather to be called a total want of philosophy.
XLIII. Not only with regard to the angels, but on the part of brutes also, we find motives for doubting, whether the definition of rational animal, may not be applied to them as well as to man. If rational animal signifies an animal capable of reflexion, the brutes are rational animals in the opinion of all those, who suppose them to be endowed with reason and reflexion: and as this sentiment may be supported by strong arguments, it remains somewhat doubtful, whether rationality is not diffused in different proportions to other animals as well as men, or whether it is confined to them only. It is true, that if this opinion should be admitted, we should grant, that the reason of man is distinct from, and of a superior nature to that of brutes; but if in the definition, we do not point out the character which distinguishes them, we are reduced to assign as the difference, a generical idea.
SECT. X.
XLIV. As we ascend the predicamental tree, and advance from the species, to the genuses or kinds; we perceive, that philosophy does not discern these more clearly, than it did the others; for we find in both cases, equal ignorance, and equal uncertainty. If we ought to have scientific certainty of any one genus in preference to another, it should be of that under which we ourselves are comprehended, which is the animal kind, for that is the thing which most immediately relates to us, and because also, we employ more consideration and attention upon that, than we do upon the others. We call the order animal, which comprehends man, and every other species of terrestrial and aquatic brutes, as likewise every kind of fish or fowl. And what do we know of animals according to this general description? Why that they are sensitive living beings; for that is the definition we give of them. But do we know this with any degree of certainty? By no means; for it has been doubted whether every animal is sensitive; and it has also been doubted, whether the sense of feeling does not belong to other entities as well as to animals.
XV. The first doubt is built upon the opposition and arguments of the Cartesians, who pretend, that all brutes are inanimate machines, and that there is no other sensible animal but man; for which reason, in their opinion, a sensible being is not a generical entity, but a specific one, and proper to the human species in a quarter proportion. I am thoroughly persuaded, that this opinion of the Cartesians is a false one; but I have not yet seen any evident argument or demonstration to confront it; nor has any person hitherto, hit upon one that evinces the falsity of it; for their principal foundation is not so weak, but that it has puzzled the most able Aristotelites to give an answer to it. But I do not find, that this is any obstacle to our giving our firm assent to the sensibility of brutes; although we have no reason to glory in our proofs of this matter, when the contrary opinion, besides the arguments that are produced to support it, finds so many partizans; and among them some of excellent ingenuity. Nor have we any reason to suppose, what I have known many people maintain, that all the Cartesians, think differently from what they speak in this matter; for some of them, are as full of the caprice that brutes are insensible, as we are of the persuasion that the contrary is the fact. A few years ago, certain ladies who were present at a bull-feast, seemed to express great concern for the sufferings of one of the bulls, which the people employed for that purpose, worried excessively. A French lady, who was a Cartesian philosopher, that sat near them, begged they would not grieve, for says the good Cartesian with great gravity, I believe as firmly as I do in God and this cross, that the bull feels no more pain than the bench I sit on. I do not know whether the other ladies believed her, but I am persuaded, that many are stedfastly of the same opinion with the French lady.
XLVI. The second doubt, whether other entities besides animals are not sensible, is patronized by Campanela, who labours by a variety of arguments, to prove in divers parts of his Works, that all elemental things are sensible. This doubt is also supported, and with more colour of reason, by those philosophers, who allow feeling to plants. And that this opinion may not appear extravagant; for the information of those who adopt the common sentiment, it will not be amiss to let them know, that Aristotle did not look upon this thing in that light, for he rather inclines to patronize the doubt; for in his first book de Plantis, he says, there is no certainty whether plants are, or are not, endued with feeling, appetite, and knowledge: Nec enim constat, habeant ne plantæ animam, appetendique facultatem, doloris item, & voluptatis, & rerum discretionis. In the third place, the naturalists, who build upon experimental observations, attribute feeling to some determined species of plants, which on that account, they call sensitive plants.
SECT. XI.
XLVII. If of our own proper genus, we know nothing with certainty, what must our knowledge be of others? The genus most immediately next to our own, is that of plants, and in this, notwithstanding our proximity, we can discern nothing but our ignorance; for we cannot venture even by conjectures, to point out the constitutive difference between them. This is not only invisible to the eyes of evidence, but impalpable to the essays of opinion. We commonly define the genus of a plant, by the term insensible living entity. But the word insensible, which we use to describe the difference, only signifies want of sensibility; and a positive entity, such as a plant is, cannot be ascertained by a negative. Besides this, as we observed before, it is somewhat doubtful, whether plants are, or are not sensible. We call them also living vegetables. But by this idea, we do not assign to the plant a different nature from the animal, for that this also is a living vegetable. If I am told, that the difference consists, in that the life of the animal is vegetative and sensitive, and that that of the plant is purely vegetative, I reply, that the adverb purely in this place, signifies nothing but the want of sensitive life, which is meant to be expressed in the extreme, and a want, cannot be made use of as a descriptive term, to point out the constitutive difference between positive entities. Nor will it be of any use to answer, that the term want, means a want or defect in the mode of explanation, and does not apply to the thing signified; for till it can be ascertained what the thing signified is, we must remain totally in the dark; and it is also false, that this term want, is not applicable to the thing signified; for negative expressions are positive with respect to the thing signified, when they are used to deny any imperfection in the object they relate to; for the want of an imperfection, is the want of a want, it being certain, that all imperfection consists in the want of positive perfection; for which reasons these words, infinity, immensity, indivisibility, although negative with respect to the mode of expression, are positive with respect to the thing signified; but the term insensible, or insensibility, applied to a plant, signifies want of perfection, and thus is negative with respect to the thing signified.
XLVIII. Besides this, some express a doubt, whether plants are vegetable or not; and some are also doubtful, whether the property of vegetation does not likewise belong to stones and metals. If we consult the Cartesians upon this point, they will tell us, that all we call vegetation or nutrition of plants, is pure mechanism, and that the attraction of the nutritious juice which we attribute to them, is a solemn chimera. If we forsake the Cartesians, and apply to the experimental philosophers, we shall find many of them, who will tell us, that metals and stones grow by means of vegetation; which is an opinion, that not long ago, was illustrated by Joseph Pitton de Tournfort, a celebrated naturalist of the Academy Royal of Sciences at Paris, and more especially, by the celebrated observations he made upon marble in the wonderful cave of Antiparos; and with respect to metals, we, to the authority of others, shall add that of Aristotle, who in his book de Mirabilibus Auscultationibus, says, that in a territory of the island of Cyprus, they were used to sow iron, and that it grew and vegetated like other plants.
XLIX. And now we are speaking of Aristotle, we will not omit mentioning an authority of his, which is very applicable to our present subject, because it is totally opposite to a received opinion in the schools, to wit, that plants and animals are of two different genuses, and that the distinction between them is, that the animal is a living sensible entity, and the plant a living insensible one. Aristotle in his book de Plantis says, that oysters and other shell-fish, are both plants and animals: scimus autem, quod conchyla animalia sunt cognitione carentia: quapropter plantæ sunt, & animalia. I ask now, how one species can be classed under two diametrically opposite genuses? and how an oyster can be both sensible and insensible? for as an animal, it ought to be a living sensible entity, and as a plant, a living insensible one. Nor can it be said, that Aristotle, when he called an oyster a plant, spoke in a metaphorical sense, for this mode of speaking is not allowed to philosophers, but is only permitted to poets and orators. Besides, the cause he assigns, shews, that he spoke in a rigorous philosophical sense; although, to speak the truth, I do not comprehend who could reveal to Aristotle, that oysters and other shell-fish are destitute of that sort of knowledge, which is proper and natural to the most stupid brutes.
SECT. XII.
L. From the lowest species, we proceed to the next above, and enquire, what is the nature of a living entity; what we are to understand by the term living, and what is life? To this, we shall be answered from the schools, that life is motion ab intrinsico, and that living, means that which moves ab intrinsico; that is, its motion is produced by some intrinsic faculty, or virtue, which it has within itself.
LI. This definition is incumbered with greater difficulties than the antecedent ones. All the modern philosophers oppose it, although for distinct and contrary reasons. Gassendo, father Maignan, and the other atomists, attribute motion ab intrinsico to atoms, from which dogma it will follow, that motion ab intrinsico, is not distinctly peculiar to living animals. The Cartesians are very positive in maintaining, that nothing can give motion to itself, but that all motion in the universe, proceeds from that impulse, which God in the beginning gave to matter, which does, and ever will subsist, without being impaired or injured; and that by virtue of that impulse, motion is communicated from one part of matter to another; so that all which was before at rest, upon its beginning to move, received its impulse from some other body which was in motion before, and transferred its influence to that which was then at rest; and either partly, or in the whole, gave it the power of beginning to move; and they say further, that man, which is the only living corporeal entity they admit, when he moves, cannot be properly said to give motion to his members, but only directs their motion by his will, in virtue of the power antecedently impressed by the impulse of other bodies on the animal spirits.
LII. It cannot be denied, that this doctrine is terribly fortified, by the celebrated maxim of Aristotle, which says, that every thing that moves, is set in motion by something else: and although the followers of the common opinion, explain this maxim, so as to render it not incompatible with the definition they give of living entities, there results from this explanation, the inconvenience, that it weakens the principal force of the axiom which they avail themselves of to prove the existence of a first mover, to stimulate a body at rest; for if we suppose, that a living entity has the power of moving itself, we cannot maintain the necessity of a divine influence to produce this motion, without admitting at the same time, the existence of a first mover in other respects, to be established. Thus it seems to me, that the Cartesians can with some colour of reason pretend, that religion is interested in understanding the axiom in all the rigour, which they profess to understand it themselves.
LIII. But be it as it may, with respect to this difficulty, and all others, which the moderns by virtue of their principles can oppose to the doctrine of Aristotle; it is certain, that there may be very serious ones urged against their definition of living entities. Heavy bodies move ab intrinsico, and are not living entities. Fire moves ab intrinsico, and is not a living entity. The fermentative motion also, according to common physics, is understood to be ab intrinsico. And I have remarked and proved in another part of this work, that what the Aristotelites say of heavy bodies being moved by communicated impulse, in the form this explanation is intelligible, is also applicable to the motion of living entities.
SECT. XIII.
LIV. There now only remains within the compass of the predicamental scale, one other thing to consider, which is the highest, and most sublime within the reach of physics, and that is, the nature and composition of the body; but where will this lead us to, the point being equally doubtful with all the rest? The composition of the body, is divided into elemental and mixed; but as this last is composed of the other, unless we know what the elemental is, it is impossible to know of what the mixture consists. Very well; but who knows the nature and number of the elements? To this question, methinks I hear four answers, from four sects of philosophers, which are all different, although each pretends to exclude the others from a competent knowledge of the matter. The Aristotelites say, that they are air, fire, earth, and water. The chymists, that they are salt, sulphur, mercury, earth, and water. The Cartesians insist, that they are composed of the subtil, the globulous, and another matter which is more gross, and which they call the third element; and the atomists, that they consist of the atoms. These are the opinions, which are at present the most prevailing, although there are numbers of others which I shall omit to mention, because they have but few votaries. Now which of these opinions is the true one? Perhaps neither. At least there is but one sect out of the four that admits either of them to be true, and whichever that sect adheres to, the other three assert to be false; which amounts to the same, as saying that one witness deposes to the truth of the matter in question, and that three give testimony against it. Thus no judge to whom the decision is confided, can give sentence in favour of either of the parties; it being out of his power to affirm, that any one of their systems is right and true.
LV. As the audience before whom I propound this reflection, is composed chiefly of the followers of Aristotle, methinks I hear them exclaim, that if we were to collect the suffrages of the academic professors, we should find most votes in favour of his opinion. To this, I reply in the first place, that although a plurality of sectaries, gives greater extrinsic probability to an opinion, still it does not afford certainty, nor intrinsic probability; and the question here, is not whether Aristotle’s opinion is the most probable, but whether it is certain. I reply secondly, that it is doubtful, if we were to include the professors who teach physics in all nations, whether we should in reality find a majority of votes in favour of Aristotle; and unless we could prove by some authentic instrument, that God has limited the knowledge of philosophy to our nation only, and has excluded all others from inheriting the science, I do not know upon what pretension we can ground a right, of admitting none but Spaniards to vote in the question. Some of our antient professors say, that we should not regard the opinions of strangers, because they are novelists; but at the same time, strangers reply, that we should take no account of what the Spaniards assert, because they are obstinate and wrong-headed, and that there is no proof, be it ever so clear, that will make them depart from their old opinions; to which they add, that in Spain, they do not follow Aristotle from choice, but from necessity; for that it requires an heroic spirit, to contradict any thing that has been advanced by Aristotle in that kingdom, where whoever dares venture to oppose him, is instantly assailed by tempests of injuries, which fall on his head like violent hail storms. Nor is even an heroic spirit, sufficient to enable a man to support such an opposition, because the duty of obedience, obliges people not to depart from the line of their school; and this is also frequently the case, in other countries; and from hence, some Anti-Aristotelites have insisted, that the plurality of votes in favour of Aristotle should not prevail, because they cannot be supposed to be free.
LVI. But abstracted from the quantum of extrinsic probability, contained in the doctrine of Aristotle respecting the elements; I assert, that upon a strict examination, you will not find more truth contained in his sentiments, than in those of his adversaries. This opinion, I deduce from the position, that his first qualities consist of four, to wit, heat, cold, wet, and dry, from which in exact proportion, he attributes one to be impregnated in the highest degree with each element, and another near to the highest. This proof, goes lame in innumerable particulars. First, the giving to these qualities the title of first, is conferring a mere voluntary dignity on them, and especially, when we know the invincible difficulty, that attends establishing, that all the others result from them. Secondly, it is very doubtful, whether all the four beforementioned, can properly be called qualities; for many Aristotelites, and with great colour of reason, deny humidity and dryness to be such. That which is humid, is not so from any quality it possesses in itself, but because it has imbibed into its pores some foreign liquid substance, and let that be evaporated, and it will remain dry; from which we may conclude, that humidity is a substance, and that dryness consists in the want of that substance. Thirdly, the appropriating these as two of the four elements, is done without any foundation or reason. In the next place, how can they prove that water is cold in the highest degree? If this was true it would kill us; neither can they prove it so, in a more moderate, or secondary degree, for we are taught by experience, it is indifferent to both cold and heat, according to the agent that is applied to it. It is heated by the fire; and remove it from the fire, and it becomes cool again, not because it has any propensity or natural disposition to be cold, but because it is made so, by the cool atmosphere which surrounds it. There are many other very grave objections to be urged against this doctrine of the four qualities; and therefore the foundation upon which it is built, and the reasoning deduced from it to establish the quaternian system of the elements, are both very slight and futil.