Part III, Chapter 19: Of the different Ways of Reasoning ill, which are called Sophisms (first part)
ALTHOUGH, if we know the rules of good reasoning, it may not be difficult to recognise those which are bad, nevertheless, as examples to be avoided often strike us more than examples to be imitated, it will not be without its use to set forth the principal classes of bad reasoning, which are called sophisms or paralogisms, since this will enable us yet more readily to avoid them. We have reduced all these to seven or eight, some being so gross that they are not worthy of being noticed.
Proving something other than that which is in dispute.
This sophism is called by Aristotle ignoratio elenchi, that is to say, the ignorance of that which ought to be proved against an adversary. It is a very common vice in the controversies of men. We dispute with warmth, and often without understanding one another. Passion, or bad faith, leads us to attribute to our adversary that which is very far from his meaning, in order to carry on the contest with greater advantage; or to impute to him consequences which we imagine may be derived from his doctrine, although he disavows and denies them. All this may be reduced to this first kind of sophism, which an honest and good man ought to avoid above all things.
It could have been wished that Aristotle, who has taken pains to point out to us this defect, had been more careful to avoid it; for it must be confessed that he has not combated honestly many of the ancient philosophers in reporting their opinions. He refutes Parmenides and Melissus for having admitted only a single principle of all things, as if they had understood by this principle that of which they are composed, whereas, they meant the single and unique principle from which all things have derived their origin—which is God.
He blames all the ancients for not having recognised privation as one of the principles of natural things, and he treats them, on this account, as clowns and fools. But who does not see, that what he represents as a great mystery which had been unknown till he revealed it, could never have been unknown to any one, since it is impossible not to see that the matter of which we make a table must have had the privation of the form of a table, that is to say, that it was not a table before it was made into a table? It is true that these ancients had not availed themselves of this knowledge to explain the principles of natural things, since, in reality, there is nothing which could less contribute to this purpose, it being sufficiently evident that we do not at all know better how to make a clock in consequence of knowing that the matter of which it is made could not have been a clock before it was made into a clock.
It is, therefore, unjust in Aristotle to reproach the ancient philosophers with having been ignorant of a thing which it is impossible to be ignorant of, and to accuse them of not having employed, for the explanation of nature, a principle which could explain nothing; and it is an illusion and a sophism to have produced to the world this principle of privation as a rare secret, since it is not this that we look for, when we attempt to discover the principles of nature. We suppose it to be well known that a thing is not, before it is made, but we wish to know of what elements it is composed—by what cause it has been produced.
There never was, for example, a sculptor, who, in instructing any one how to make a statue, would have given, as the first instruction, that lesson by which Aristotle would begin the explanation of all the works of nature:—My friend, the first thing that it behoves you to know is, that in order to make a statue, it is necessary to choose a piece of marble which is not already that statue which you wish to make.
Assuming as true the thing in dispute.
This is what Aristotle calls a begging of the question, which is clearly altogether opposed to true reasoning, since, in all reasoning, that which is employed as proof ought to be clearer and better known than that which we seek to prove.
Galileo, however, has accused him, and with justice, of having himself fallen into this error, when he tried to prove that the earth was at the centre of the world, by this argument: —
The nature of heavy things is to tend to the centre of the world, and of light things to go off from it; Now, experience proves that heavy things tend towards the centre of the earth, and that light things go off from it;
Therefore, the centre of the earth is the same as the centre of the world.
It is clear that there is in the major of this argument a manifest begging of the question; for we see well enough that heavy things tend towards the centre of the earth; but where did Aristotle learn that they tend towards the centre of the world, unless he assumed that the centre of the earth is the same as the centre of the world?—which is the very conclusion that he wishes to prove by that argument.
Among the pure beggings of the question, too, are the greater part of those arguments which are employed to prove certain anomalous kinds of substances, which are called, in the schools, substantial forms; these, it is maintained, are corporeal, though they have no body, which it is difficult enough to comprehend. If there are not substantial forms, say they, there could be no generation; now, there is generation in the world, therefore, there are substantial forms.
We have only to distinguish the equivocation in the word generation, in order to see that this argument is but a pure begging of the question; for if we understand by the word generation the natural production of a new whole in nature, as the production of the chicken which is formed in an egg, we may say, with reason, that there are generations in this sense; but we cannot conclude that there are substantial forms, since the simple arrangement of parts, by nature, may produce these new wholes, and these new natural beings. But if by the word generation is understood what they commonly understand by it, the production of a new substance which did not exist before, to wit, that substantial form, the very thing which is in dispute, is assumed; since it is plain that he who denies substantial forms will not allow that nature produces substantial forms; and so far is it from being necessary that he should be led, by this argument, to avow such production, that he ought rather to derive from it a directly contrary conclusion in this way: If there are substantial forms, nature must produce something which did not exist before. Now, nature did not produce new substances, since this would be a kind of creation; and, consequently, there are no substantial forms.
The following is another of the same kind:—If there are not substantial forms, say they again, natural beings would not be wholes, which they term per se, totum per se, but beings per accidens; now, they are wholes per se; therefore there are substantial forms.
It is still necessary to ask those who employ this argument to have the goodness to explain what they understand by a whole per se, totum per se; for if they understand, as they do, a being composed of matter and of form, it is clear that this is a begging of the question, since it is as though they should say—If there are not substantial forms, natural beings could not be composed of matter, and substantial forms; now, they are composed of matter, and substantial forms; therefore, there are substantial forms. But if they understand anything else, let them say so, and we shall see that they prove nothing.
We have thus stopped a little by the way, to show the feebleness of the arguments on which are established, in the schools, these sorts of substances, which are discovered neither by the sense nor by the mind, and of which we know nothing further than that they are called substantial forms; because, although those who defend them do so with a very good intention, the principles, nevertheless, which they employ, and the ideas which they give of these forms, obscure and disturb the very solid and convincing proofs of the immortality of the soul which are derived from the distinction of minds and bodies, and from the impossibility of any substance, which is not matter, perishing through the changes which happen to matter; for, by means of these substantial forms, we unwittingly furnish free thinkers with examples of substances which perish, which are not properly matter, and to which we attribute in animals a multitude of thoughts, that is to say, of actions purely spiritual. Hence, it is useful, for the sake of religion, and for the conviction of the scoffers and irreligious, to take away from them this reply, by showing that nothing can rest on a worse foundation than these perishable substances which are called substantial forms.
We may reduce, also, to this kind of sophism, the proof which is derived from a principle different from that which is in dispute, but which we know is equally contested by him with whom we dispute. There are, for example, two dogmas equally established amongst catholics; the one, that all the points of faith cannot be proved by Scripture alone; the other, that it is a point of faith that infants are capable of baptism. It would, therefore, be bad reasoning in an anabaptist to prove against the catholics that they are wrong in believing that infants are capable of baptism, since nothing is said of it in the Scripture, because this proof would assume that we ought to believe only what is in the Scripture, which is denied by the catholics.
Finally, we may bring under this sophism all reasonings in which we prove a thing unknown, by another equally or more unknown; or an uncertain thing, by another which is equally or more uncertain.