Should your opponent expressly challenge you to produce any objection to some definite point in his argument, and you have nothing much to say, you must try to give the matter a general turn, and then talk against that. If you are called upon to say why a particular physical hypothesis cannot be accepted, you may speak of the fallibility of human knowledge, and give various illustrations of it.
When you have elicited all your premisses, and your opponent has admitted them, you must refrain from asking him for the conclusion, but draw it at once for yourself; nay, even though one or other of the premisses should be lacking, you may take it as though it too had been admitted, and draw the conclusion. This trick is an application of the fallacy _non causae ut causae_.
When your opponent uses a merely superficial or sophistical argument and you see through it, you can, it is true, refute it by setting forth its captious and superficial character; but it is better to meet him with a counter-argument which is just as superficial and sophistical, and so dispose of him; for it is with victory that you are concerned, and not with truth. If, for example, he adopts an _argumentum ad hominem_, it is sufficient to take the force out of it by a counter _argumentum ad hominem_ or _argumentum ex concessis_; and, in general, instead of setting forth the true state of the case at equal length, it is shorter to take this course if it lies open to you.
If your opponent requires you to admit something from which the point in dispute will immediately follow, you must refuse to do so, declaring that it is a _petitio principii_ For he and the audience will regard a proposition which is near akin to the point in dispute as identical with it, and in this way you deprive him of his best argument.
Contradiction and contention irritate a man into exaggerating his statement. By contradicting your opponent you may drive him into extending beyond its proper limits a statement which, at all events within those limits and in itself, is true; and when you refute this exaggerated form of it, you look as though you had also refuted his original statement. Contrarily, you must take care not to allow yourself to be misled by contradictions into exaggerating or extending a statement of your own. It will often happen that your opponent will himself directly try to extend your statement further than you meant it; here you must at once stop him, and bring him back to the limits which you set up; "That's what I said, and no more."
