Our best 50 ideas of the century series is continued by Jon Williamson

Explication is an old idea that has gained a new lease of life in the last decade. While Hobbes made philosophical use of explication, writing that “Definitions … are nothing but the explication of our simple conceptions,” it was Rudolf Carnap who first thoroughly explored the serious philosophical work that explication can do. Carnap opened his 1950 book Logical foundations of probability with a discussion of explication, maintaining that “the task of explication consists in transforming a given more or less inexact concept into an exact one or, rather, in replacing the first by the second.” In the rest of the book, he went on to use probability theory to explicate the concept of degree of confirmation.

What counts as a good explication? According to Carnap, an explicating concept should be similar to the explicated concept inasmuch as one should be able to replace most of the uses of the latter by the former; it should be precisely formulated; it should be fruitful; and it should otherwise be as simple as possible. Explication offers an interesting departure from other methods of philosophical analysis in that an explicating concept need not be true to all the uses of the explicated concept. Note that explication should not be confused with explanation. Explication transforms concepts, making them more precise, while explanation chiefly seeks to answer “why?” questions.

The process of explication has been undeniably successful in honing some of our most fundamental concepts. For example, the concept of validity was given a formal explication that underwrites all of modern logic. Kolmogorov’s 1933 explication of the concept of probability replaced the informal notion of probability and has been tremendously fruitful. In the 1980s, AI researchers developed the Bayesian net explication of the informal concept of causality. This last explication is particularly exciting because it is still very much up in the air: while the Bayesian net explication is elegant and fruitful, there remain major worries about whether it is similar enough to our common conception of causality for us to be able to replace the common conception by the explication.

Having fallen out of fashion in the second half of the 20th century (due in part to some early criticisms of Peter Strawson’s), the philosophical use of explication has made a comeback since the turn of the millennium. There has been renewed debate in the last decade as to whether explication is a viable method of philosophical analysis. Giovanni Boniolo has argued that it isn’t, because explication is more akin to definition than to analysis. Anthony Eagle has argued that it isn’t, because the explicating concept is itself in need of conceptual clarification. But Patrick Maher has defended explication against these criticisms and recent widespread use of explication in philosophy suggests that the critics are now in the minority.

This rehabilitation of explication has opened the floodgates to the use of formal methods in philosophy. After half a century in the doldrums, the use of formal methods has really taken off in the last decade, nowhere more so than in epistemology (the study of knowledge and belief). While formal methods have been used to explicate strength of belief at least since James Bernoulli’s “Art of Conjecture” of 1713, it is only in the last decade that formal epistemology has really boomed: this year we have the 7th of a series of annual Formal Epistemology Workshops and have just had the 3rd annual Formal Epistemology Festival; Igor Douven’s Formal Epistemology Project in Leuven is a good example of the large-scale funding that formal epistemology can attract. Formal methods are also dominating the study of reasoning, as can be seen by glancing through the pages of The Reasoner at www.thereasoner.org. In 2010, research centres and groups employing formal methods in philosophy abound – a new Centre for Mathematical Philosophy, to be established in Munich by Hannes Leitgeb in coming months, is but the latest example.

Explication, then, is as exciting a tool for philosophers as it is for scientists and – as we are beginning to see – it is a tool with important consequences for philosophical practice.

Further reading
“Explication defended”, Patrick Maher, Studia Logica 86: 331-341, 2007, freely available at http://patrick.maher1.net/ed.pdf.

Jon Williamson is Professor of Reasoning, Inference and Scientific Method at the University of Kent and editor of The Reasoner

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