In 1908, William McDougall published the first edition of An Introduction to Social Psychology. Paradoxically, the book presented his theory of personality. In the Preface to the 14th edition, McDougall defended his choice of that title by arguing that one cannot understand social psychology without first accounting for “the innate tendencies of human nature and their organization under the touch of individual experience to form the characters of individual men” (1919/1963, p. xvii). He continued throughout his career to maintain that dispositional tendencies must be considered as fundamental and indispensable postulates for all psychology (McDougall, 1938).

We agree with McDougall that understanding personality structure, development, and dynamics is prerequisite to explaining adult social behaviour. Many behaviourists, sociologists, and social psychologists, however, vehemently disagree with this core assumption of personality psychology and argue instead that behaviour is a function of the situation in which it occurs. As a result, the literature contains recurring cycles of debate about the existence and importance of personality traits (Allport, 1937, ch. 11; Magnusson & Endler, 1977; Mischel, 1968; Murphy, 1947, ch. 38; Sanford, 1956; Watson & McDougall, 1929). At present, the idea that internal dispositions have an important influence on behaviour appears to be enjoying increased acceptance (Kenrick & Fun der, 1988; Rowe, 1987). Whether or not the status and popularity of personality psychology will continue to be cyclical, we believe that Mc-Dougall's conceptualisation must be taken seriously for the simple reason that it is essentially correct.

In this chapter we take the position that a trait approach is the indispensable foundation for a complete psychological understanding of shyness.