 The study of logic does not in itself suffice to enable us to reason correctly, still less to think clearly where our passionate beliefs are concerned. Thinking is an activity of the whole personality. Given, however, a desire to be reasonable, then a knowledge of the conditions to which all sound thinking must conform will enable us to avoid certain mistakes into which we are prone to fall. There is such a thing as a habit of sound reasoning. This habit may be acquired by consciously attending to the logical principles of sound reasoning, in order to apply them to test the soundness of particular arguments. (1934a: vii–viii)