ABSTRACT
Reduction is a relation of logical derivation between statements or theories. Hooker provides examples illustrating the logical diversity and 'bewildering variety and complexity' of reductions. A prerequisite for reduction is the ordering of sciences from higher to lower levels, e.g. sociology, psychology, physiology, chemistry, physics. All interesting cases of reduction also require a further condition, that of definability, i.e. a mapping of the terms in the two theories, by biconditionals or some kind of bridging laws. There has been a historical shift, in the conditions considered necessary for reduction, away from positivism. Schaffner, in a useful paper, describes four versions of reduction, two positivist models and two weaker modifications: Hooker postulates a retention-replacement continuum, which determines whether a reduction is smooth or bumpy. The main arguments in favour of reduction are theoretical unification and increased explanatory power, as well as mutual benefit resulting from research cooperation between disciplines.
