Sophistic & Logic
Another trick is to take a proposition which is laid down relatively, and in reference to some particular matter, as though it were uttered with a general or absolute application; or, at least, to take it in some quite different sense, and then refute it. Aristotle's example is as follows:
A Moor is black; but in regard to his teeth he is white; therefore, he is black and not black at the same moment. This is an obvious sophism, which will deceive no one. Let us contrast it with one drawn from actual experience.
In talking of philosophy, I admitted that my system upheld the Quietists, and commended them. Shortly afterwards the conversation turned upon Hegel, and I maintained that his writings were mostly nonsense; or, at any rate, that there were many passages in them where the author wrote the words, and it was left to the reader to find a meaning for them. My opponent did not attempt to refute this assertion ad rem, but contented himself by advancing the argumentum ad hominem and telling me that I had just been praising the Quietists, and that they had written a good deal of nonsense too.
This I admitted; but, by way of correcting him, I said that I had praised the Quietists, not as philosophers and writers, that is to say, for their achievements in the sphere of theory, but only as men, and for their conduct in mere matters of practice; and that in Hegel's case we were talking of theories. In this way I parried the attack.
The first three tricks are of a kindred character. They have this in common, that something different is attacked from that which was asserted. It would therefore be an ignoratio elenchi to allow oneself to be disposed of in such a manner.
For in all the examples that I have given, what the opponent says is true, but it stands in apparent and not in real contradiction with the thesis. All that the man whom he is attacking has to do is to deny the validity of his syllogism; to deny, namely, the conclusion which he draws, that because his proposition is true, ours is false. In this way his refutation is itself directly refuted by a denial of his conclusion, per negationem consequentiae. Another trick is to refuse to admit true premisses because of a foreseen conclusion. There are two ways of defeating it, incorporated in the next two sections.