ABSTRACT

Social scientists often seek to explain and predict human behaviour. Two well-known ways of doing so are Ryan and Deci’s (2000) self-determination theory (SDT) and Ajzen’s (1991) theory of planned behaviour (TPB). Both SDT and TPB meet commonly espoused criteria for ‘good’ theory (Popper, 1959, including being parsimonious (e.g., Crawford and Jackson, 2005)). But in striving for parsimony ‘theory shyness’ may have inadvertently resulted; that is, an overemphasis on more modest ‘midrange’ theorizing at the expense of more broad, unitary, or ‘grand’ theorizing (Kruglanski, 2001). Merton was amongst the first to discuss this trade-off, stating several years ago that:

I believe – and beliefs are of course notoriously subject to error – that theories of the middle range hold the largest promise, provided that the search for them is coupled with a pervasive concern with consolidating special theories into more general sets of concepts and mutually consistent propositions. Even so, we must adopt the provisional outlook of our big brothers and of Tennyson: ‘Our little systems have their day; They have their day and cease to be.’

(Merton, 1968, pp. 52–53) Popper (1959; as cited in Kruglanski, 2001) and Kruglanski (2001) concurred, with both prompting social scientists to have the ‘guts’ to propose more general theory.