lie causes to other men; another from the worthlessness of a liar
and the violation of his own self-respect, what is proved in the
former argument is a duty of benevolence, not of veracity, that is
to say, not the duty which required to be proved, but a different one.
Now, if, in giving a variety of proof for one and the same theorem, we
flatter ourselves that the multitude of reasons will compensate the
lack of weight in each taken separately, this is a very
unphilosophical resource, since it betrays trickery and dishonesty;
for several insufficient proofs placed beside one another do not
produce certainty, nor even probability. They should advance as reason
and consequence in a series, up to the sufficient reason, and it is
only in this way that they can have the force of proof. Yet the former
is the usual device of the rhetorician.

Secondly. The difference between virtue and vice cannot be sought in
the degree in which certain maxims are followed, but only in the
specific quality of the maxims (their relation to the law). In other
words, the vaunted principle of Aristotle, that virtue is the mean
between two vices, is false. * For instance, suppose that good
management is given as the mean between two vices, prodigality and
avarice; then its origin as a virtue can neither be defined as the
gradual diminution of the former vice (by saving), nor as the increase
of the expenses of the miserly. These vices, in fact, cannot be viewed
as if they, proceeding as it were in opposite directions, met together
in good management; but each of them has its own maxim, which
necessarily contradicts that of the other.

{INTRODUCTION ^paragraph 165}