What is thought and thinking? This question is at least as old as western philosophy. It will occupy us throughout this part of the book. It is not the same question as asking about the meaning of ‘think’ and ‘thought’ in modern English. In different languages in different historical periods different words are used to cover the variety of phenomena associated in pre-theoretical common-sense thinking with thought. This concept encompasses many different processes. We shall give it the label ‘cognition’ and leave it undefined since the many different states and processes under the label do not admit of a sharp delineation. Here are some examples indicating the subject of our inquiry. Thinking of something, having a concept of something, understanding, explaining, thinking, and believing. Corresponding to these verbal notions we have nouns like thought, concept, intelligibility, belief, judgement. In addition to these positive notions cognition includes also doubt and questioning. There are two ways of indicating a common element among the items cited. One of these is to claim that for these activities and states and for the expression of their results language is necessary. This claim needs qualifications. One of these is that the need for language is related to these activities and states attaining a certain level of complexity. This level is empirically determined, and today opinions vary as to where to draw the line. But it is worth noting that as phrased here the claim does not rule out animal cognition of various kinds. The other way of finding the common denominator is to claim that expressing what goes on in these states and activities is one of the key tasks of natural languages. According to this view, language may or may not be needed for every cognitive process. It does not rule out pre-verbal or non-verbal 47thinking. It does say, however, that language typically expresses or embodies the outcome of various cognitive processes.