Example 3.--Lamarck, in his _Philosophic Zoologique_ (vol. i., p. 208), states that the polype has no feeling, because it has no nerves. It is certain, however, that it has some sort of perception; for it advances towards light by moving in an ingenious fashion from branch to branch, and it seizes its prey. Hence it has been assumed that its nervous system is spread over the whole of its body in equal measure, as though it were blended with it; for it is obvious that the polype possesses some faculty of perception without having any separate organs of sense. Since this assumption refutes Lamarck's position, he argues thus: "In that case all parts of its body must be capable of every kind of feeling, and also of motion, of will, of thought. The polype would have all the organs of the most perfect animal in every point of its body; every point could see, smell, taste, hear, and so on; nay, it could think, judge, and draw conclusions; every particle of its body would be a perfect animal and it would stand higher than man, as every part of it would possess all the faculties which man possesses only in the whole of him. Further, there would be no reason for not extending what is true of the polype to all monads, the most imperfect of all creatures, and ultimately to the plants, which are also alive, etc., etc." By using dialectical tricks of this kind a writer betrays that he is secretly conscious of being in the wrong. Because it was said that the creature's whole body is sensitive to light, and is therefore possessed of nerves, he makes out that its whole body is capable of thought. II. The _Homonymy_.--This trick is to extend a proposition to something which has little or nothing in common with the matter in question but the similarity of the word; then to refute it triumphantly, and so claim credit for having refuted the original statement. It may be noted here that synonyms are two words for the same conception; homonyms, two conceptions which are covered by the same word. (See Aristotle, _Topica_, bk. i., c. 13.) "Deep," "cutting," "high," used at one moment of bodies at another of tones, are homonyms; "honourable" and "honest" are synonyms. This is a trick which may be regarded as identical with the sophism _ex homonymia_; although, if the sophism is obvious, it will deceive no one. _Every light can be extinguished. The intellect is a light. Therefore it can be extinguished_. Here it is at once clear that there are four terms in the syllogism, "light" being used both in a real and in a metaphorical sense. But if the sophism takes a subtle form, it is, of course, apt to mislead, especially where the conceptions which are covered by the same word are related, and inclined to be interchangeable. It is never subtle enough to deceive, if it is used intentionally; and therefore cases of it must be collected from actual and individual experience.