Why Psychology Cannot Be Reduced to Causal Science

Psychology occupies an anomalous position among the sciences because its subject matter — the mind — straddles what philosophers distinguish as the space of causes and the space of reasons. Natural-scientific explanation is causal and mechanistic, but psychological explanation necessarily traffics in reasons, which are normative: they involve correctness, validity, and value. Piaget captured this tension with the phrase 'normative fact' — the truth that two plus two equals four is not a causal regularity but a normative entailment. This dual character means that the Disenchantment and reductionism that powered the natural sciences cannot be imported wholesale into psychology without distortion.

The structural consequence is that a purely experimental, measurement-based psychology is inadequate to its own domain. It attempts to resolve normative questions — what constitutes good reasoning, appropriate emotion, healthy development — using exclusively causal tools. The result, as Zak Stein has argued, is the proliferation of 'mongrel concepts': folk-psychological notions reified through factor analysis and psychometric technique, mistaken for natural kinds, and then industrially scaled into assessment instruments that obscure rather than illuminate personhood.

A viable Metapsychology must therefore expand the metaphysical commitments of science itself, treating value and normative entailment as genuine features of reality rather than eliminable folk residue. The concept of Relevance realization, developed in the work of John Vervaeke, sits precisely at this boundary — relevance is neither purely causal nor purely rational, but constitutively involves both. This makes it a potentially pivotal concept for any metapsychological framework that aspires to integrate causal explanation with normative understanding without collapsing one into the other.