(2) Deductive.

2. The problem of inductive logic is to determine the actual truth
or falsity of propositions: the problem of deductive logic is to
determine their relative truth or falsity, that is to say, given such
and such propositions as true, what others will follow from them.

3. Hence in the natural order of treatment inductive logic precedes
deductive, since it is induction which supplies us with the general
truths, from which we reason down in our deductive inferences.

4. It is not, however, with logic as a whole that we are here
concerned, but only with deductive logic, which may be defined as The
Science of the Formal Laws of Thought.

5. In order fully to understand this definition we must know exactly
what is meant by 'thought,' by a 'law of thought,' by the term
'formal,' and by 'science.'

6. Thought, as here used, is confined to the faculty of
comparison. All thought involves comparison, that is to say, a
recognition of likeness or unlikeness.

7. The laws of thought are the conditions of correct thinking. The
term 'law,' however, is so ambiguous that it will be well to determine
more precisely in what sense it is here used.

8. We talk of the 'laws of the land' and of the 'laws of nature,'
and it is evident that we mean very different things by these
expressions. By a law in the political sense is meant a command