though you have to reach it circuitously,
masking your approach under difference of language, would clearly be
an advantage. This was the advantage that Aristotle's method offered
to supply. A disputant familiar with his analysis would foresee at
once that if he could get the Respondent to admit that all actions
undertaken for private ends are vicious, the victory was his, while
nothing short of this would serve.

Here my reader may interject that he could have seen this without any
help from Aristotle, and that anybody may see it without knowing
that what he has to do is, in Aristotelian language, to construct a
syllogism in Bokardo. I pass this over. I am not concerned at this
point to defend the utility of Aristotle's method. All that I want
is to illustrate the kind of use that it was intended for. Perhaps if
Aristotle had not habituated men's minds to his analysis, we should
none of us have been able to discern coherence and detect incoherence
as quickly and clearly as we do now.

But to return to our example. As Aristotle's pupil, you would have
seen at the stage we are speaking of that the establishment of your
thesis must turn upon the definition of virtue and vice. You must
proceed, therefore, to cross-examine your Respondent about this. You
are not allowed to ask him what he means by virtue, or what he means
by vice. In accordance with the rules of the dialectic, it is your
business to propound definitions, and demand his Yes or No to them.
You ask him, say, whether he agrees with Shaftesbury's definition of a
virtuous action as an action undertaken purely for the good of others.
If he assents, it follows that an action undertaken with any suspicion
of a self-interested motive cannot be numbered among the virtues.
If he agrees, further, that every action must be either vicious
or virtuous, you have admissions sufficient to prove your original
thesis. All that you have now to do to make your triumph manifest, is
to display the admissions you have obtained in common terms.

Some actions done with a self-interested motive are public
benefits. All actions done with a self-interested motive are
private vices.

From these premisses it follows irresistibly that

Some private vices are public benefits.

This illustration may serve to show the kind of disputation for which
Aristotle's logic was designed, and thus to make clear its primary
uses and its limitations.

To realise its uses, and jud