Unification and Explanatory Power

Unificationist accounts hold that science explains by showing how diverse phenomena fit a small number of recurring argument patterns, thereby increasing understanding.

Definition

Explanatory unification is the view that the explanatory power of a theory consists in its ability to derive many disparate facts from few independently acceptable argument patterns, reducing the number of brute regularities we must accept.

Scope

This topic covers Friedman's and Kitcher's unificationist theories of explanation, their measures of explanatory power, the contrast with causal accounts, and challenges concerning spurious unification and the direction of explanation.

Core questions

• What makes one body of theory more explanatory than another?
• Can explanatory power be measured by the economy of argument patterns?
• Does unification capture or merely correlate with genuine explanation?
• How does the unificationist account handle explanatory asymmetry?

Key concepts

• explanatory store
• argument pattern
• stringency
• economy of derivation
• global versus local explanation

Key theories

Friedman's unification account

Friedman proposes that understanding increases when the number of independently accepted phenomena is reduced by deriving them from fewer underlying laws.

Kitcher's argument-pattern account

Kitcher refines unification as the use of the smallest stringent set of argument patterns that derives the most consequences, with the best such set fixing the explanatory store.

History

Friedman's 1974 paper revived the idea that explanation yields understanding through unification, though its formal proposal faced technical objections. Kitcher's 1989 argument-pattern account became the leading unificationist theory and a principal rival to Salmon's causal-mechanical approach.

Debates

Unification versus causation

Salmon argues that unification can be spurious and may invert explanatory direction, whereas Kitcher holds that the best unifying patterns themselves track the causal structure of the world.

Key figures

• Michael Friedman
• Philip Kitcher
• Wesley Salmon

Seminal works

• friedman1974
• kitcher1989

Frequently asked questions

Why think unification produces understanding?

The intuition is that science advances when many separate facts turn out to be instances of one pattern, as when Newtonian mechanics unified terrestrial and celestial motion. Unificationists formalize this as reducing the number of independent regularities we must simply accept.