The central philosophical task posed by conventions is to analyze what they are and how they differ from mere regularities of action and cognition. Subsidiary questions include: How do conventions arise? How are they sustained? How do we select between alternative conventions? Why should one conform to convention? What social good, if any, do conventions serve? How does convention relate to such notions as rule, norm, custom, practice, institution, and social contract? Apart from its intrinsic interest, convention is important because philosophers frequently invoke it when discussing other topics. A favorite philosophical gambit is to argue that, perhaps despite appearances to the contrary, some phenomenon ultimately results from convention. Notable candidates include: property, government, justice, law, morality, linguistic meaning, necessity, ontology, mathematics, and logic.
In everyday usage, “convention” has various meanings, as suggested by the following list: Republican Party Convention; Geneva Convention; terminological conventions; conventional wisdom; flouting societal convention; conventional medicine; conventional weapons; conventions of the horror genre. As Nelson Goodman observes:
The terms “convention” and “conventional” are flagrantly and intricately ambiguous. On the one hand, the conventional is the ordinary, the usual, the traditional, the orthodox as against the novel, the deviant, the unexpected, the heterodox. On the other hand, the conventional is the artificial, the invented, the optional, as against the natural, the fundamental, the mandatory. (1989, p. 80)
Adding to the confusion, “convention” frequently serves as jargon within economics, anthropology, and sociology. Even within philosophy, “convention” plays so many roles that we must ask whether a uniform notion is at work. Generally speaking, philosophical usage emphasizes the second of Goodman’s disambiguations. A common thread linking most treatments is that conventions are “up to us,” undetermined by human nature or by intrinsic features of the non-human world. We choose our conventions, either explicitly or implicitly.
This concept is the target of David Lewis’s celebrated analysis in Convention (1969). A social convention is a regularity widely observed by some group of agents. But not every regularity is a convention. We all eat, sleep, and breathe, yet these are not conventions. In contrast, the fact that everyone in the United States drives on the right side of the road rather than the left is a convention. We also abide by conventions of etiquette, dress, eating, and so on.
Two putative social conventions commonly cited by philosophers are money and language. Aristotle mentions the former example in the Nicomachean Ethics (V.5.II33a):
Money has become by convention a sort of representative of demand; and this is why it has the name “money” (“
nomisma
nomos
and the latter example in De Interpretatione (16a.20–28):
A name is a spoken sound significant by convention… I say “by convention” because no name is a name naturally but only when it has become a symbol.
David Hume mentions both examples in the Treatise of Human Nature (p. 490):
[L]anguages [are] gradually establish’d by human conventions without any explicit promise. In like manner do gold and silver become the common measures of exchange, and are esteem’d sufficient payment for what is of a hundred times their value.
Although Hume analyzed money at some length in the 1752 “Of Money,” it now receives systematic attention mainly from economists rather than philosophers.[1] In contrast, philosophers still lavish great attention upon the extent, if any, to which language rests upon convention. David Lewis offers a theory of linguistic conventions, while Noam Chomsky and Donald Davidson argue that convention sheds no light upon language. See section 7, Conventions of language.
For many philosophers, a central philosophical task is to elucidate how we succeed in “creating facts” through our conventions. For instance, how does convention succeed in conferring value upon money or meaning upon linguistic items? Ideally, a satisfying answer to these questions would include both an analysis of what social conventions are and a description of the particular conventions underlying some range of “conventional” facts. Hume’s theory of property and Lewis’s theory of linguistic meaning serve as paradigms here.
What are social conventions? A natural first thought is that they are explicit agreements, such as promises or contracts, enacted either by parties to the convention or by people suitably related to those parties (such as their ancestors). This conception underwrites at least one famous conventionalist account: Thomas Hobbes’s theory of government as resulting from a social contract, into which agents enter so as to leave the state of nature. However, it seems clear that the vast majority of interesting social phenomena, including government, involve no explicit historical act of agreement. Social conventions can arise and persist without overt convening.
Partly in response to such worries, John Locke emphasized the notion of a tacit agreement. A tacit agreement obtains if there has been no explicit agreement but matters are otherwise as if an explicit agreement occurred. A principal challenge here is explaining the precise respects in which matters are just as if an explicit agreement occurred. Moreover, many philosophers argue that appeal even to “as if” agreements cannot explain linguistic meaning. What language would participants in such an agreement employ when conducting their deliberations? Bertrand Russell observes that “[w]e can hardly suppose a parliament of hitherto speechless elders meeting together and agreeing to call a cow a cow and a wolf a wolf” (1921, p. 190). As W. V. Quine asks, then, “What is convention when there can be no thought of convening?” (1969, p. xi). Some philosophers take this argument to show that language does not rest upon convention. Others, such as Lewis, take it as impetus to develop a theory of convention that invokes neither explicit nor tacit agreement.
Conventionalism about some phenomenon is the doctrine that, perhaps despite appearances to the contrary, the phenomenon arises from or is determined by convention. Conventionalism surfaces in virtually every area of philosophy, with respect to such topics as property (Hume’s Treatise of Human Nature), justice (Hume’s Treatise again), morality (Gilbert Harman (1996), Graham Oddie (1999), Bruno Verbeek (2008)), geometry (Henri Poincaré (1902), Hans Reichenbach (1922), Adolf Grünbaum (1962)), Lawrence Sklar (1977)), pictorial representation (Nelson Goodman (1976)), personal identity (Derek Parfit (1984)), ontology (Rudolf Carnap (1937), Nelson Goodman (1978), Hilary Putnam (1987)), arithmetic and mathematical analysis (Rudolf Carnap (1937)), necessity (A. J. Ayer (1936)), Alan Sidelle (1989)), and almost any other topic one can imagine. Conventionalism arises in so many different forms that one can say little of substance about it as a general matter. However, a distinctive thesis shared by most conventionalist theories is that there exist alternative conventions that are in some sense equally good. Our choice of a convention from among alternatives is undetermined by the nature of things, by general rational considerations, or by universal features of human physiology, perception, or cognition. This element of free choice distinguishes conventionalism from doctrines such as projectivism, transcendental idealism, and constructivism about mathematics, all of which hold that, in one way or another, certain phenomena are “due to us.”
A particularly important species of conventionalism, especially within metaphysics and epistemology, holds that some phenomenon is partly due to our conventions about the meaning or proper use of words. For instance, Henri Poincaré argues that “the axioms of geometry are merely disguised definitions,” concluding that: