David Hume (1711-1776),
An Enquiry Concerning the Principles of Morals, Section I (the first paragraph):
Disputes with Persons, pertinaciously
obstinate in their Principles, are, of all
others, the most irksome; except, perhaps,
those with Persons, who really do not believe
at all the Opinion they defend, but engage in the
Controversy, from Affectation, from a Spirit of Opposition,
or from a Desire of showing Wit and Ingenuity,
superior to the rest of Mankind. The same
blind Adherence to their own Arguments is to be expected
in both; the same Contempt of their Antagonists;
and the same passionate Vehemence, in inforcing
Sophistry and Falshood. And as reasoning is
not the Source, whence either Disputant derives his
Tenets; 'tis in vain to expect, that any Logic, which
speaks not to the Affections, will ever engage him to
embrace sounder Principles.
Id.:
Extinguish all the warm Feelings and Prepossessions
in favour of Virtue, and all Disgust or Aversion
against Vice: Render Men totally indifferent towards
these Distinctions; and Morality is no longer a practical
Study, nor has any Tendency to regulate our
Lives and Actions.