To be in a questioning frame of mind is to be thinking; reflective thinking essentially consists in attempting to solve a problem and thus in asking questions and seeking answers to these questions so as to solve the problem. We distinguish reflective thinking from idle reverie or day dreaming. In reflective thinking our thoughts are directed towards an end—the solution of the problem that set us thinking. Thinking is a mental process in which we pass from one thought to another. A thought is an element in this process which requires for its full expression a complete sentence. When one thought is more or less consciously connected with another in order to elicit the conclusion towards which our thinking is directed we are reasoning.
Reasoning is a familiar activity; we all reason more or less, badly or well. We connect various items of information and draw conclusions; we judge that, if certain statements are known to be true, then certain other statements are also true and must be accepted. In saying that the latter must be accepted we are saying that, provided we are thinking logically, we shall accept them; that is to say, we should not be rational beings if we accepted the former statements and rejected the latter.
(L. Susan Stebbing, A Modern Elementary Logic, 5th ed., rev. by C. W. K. Mundle [London: Methuen, 1952; University Paperbacks, 1961], 2 [italics in original])
