In my contribution to Professor J.W. Tibbie's volume The Study of Education1 I sought to characterise educational theory as a domain of practical theory, concerned with formulating and justifying principles of action for a range of practical activities. Because of their concern for practical principles I sharply distinguished domains of practical theory from domains concerned simply with purely theoretical knowledge. The function of the latter is primarily explanation. The function of the former is primarily the determination

of practice. The one is concerned with achieving rational understanding, the other with achieving rational action. In this approach I was in major respects at variance with that set out several years previously by Professor D.J. O'Connor in his influential book An Introduction to the Philosophy of Education.2 He had argued that though the term theory could be used for 'a set or system of rules or a collection of precepts which guide or control actions of various kinds','3 it is better used as in the natural sciences for a hypothesis or logically inter-connected set of hypotheses that have been confirmed by observation. In this sense we have 'standards by which we can assess the value and use of any claimant to the title of "theory". In particular this sense of the word will enable us to judge the value of the various (and often conflicting) theories that are put forward by writers on education.'4