A Combinatorial Theory of Possibility

by D.M. Armstrong

David Armstrong's book is a contribution to the philosophical discussion about possible worlds. Taking Wittgenstein's Tractatus as his point of departure, Professor Armstrong argues that nonactual possibilities and possible worlds are recombinations of actually existing elements, and as such are useful fictions. There is an extended criticism of the alternative-possible-worlds approach championed by the American philosopher David Lewis. This major work will be read with interest by a wide range of philosophers.

Genres: Philosophy

156 pages, Paperback

First published September 29, 1989

About the author

David Malet Armstrong (born 8 July 1926), often D. M. Armstrong, is an Australian philosopher. He is well-known for his work on metaphysics and the philosophy of mind, and for his defence of a factualist ontology, a functionalist theory of the mind, an externalist epistemology, and a necessitarian conception of the laws of nature. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 2008.

Reviews

[Jesse Maurais · Rating 4 out of 5]

A lot of literature on the topic of possible worlds, apart from modal logic, has been concerned with the ontological status of the worlds or how one constructs them, with the usual caveat on the latter that one ought not to construct impossible worlds. One approach to this problem is Lewis' infamous modal realism, for which there is no need of a construction and no concern to avoid impossible worlds because the theory simply asserts that such worlds exist or do not, and what is true or false of them is a matter of what does or does not obtain at those worlds. But "exists" in modal realism is taken in its full-blooded sense; the possible exists in every way that the actual does. Whatever its theoretical niceties, the cost of taking this view is that one must abandon common sense. Contra Lewis: the only actual world is the one in which we live and only it exists in the fullest sense.

Armstrong is defending common sense against modal realism and its kin theories. He also rejects essentialism, I think correctly (why is Socrates essentially blonde at a world where he is contingently blonde, but not simply essentially blonde, and why do I care about that distinction anyway?) But at the same time he is concerned with avoiding all the same problems that these rival theories purport to solve.

He calls possible worlds "fictions" and likens his own account of them to Lewis' "ersatz" theory. In a nutshell the theory is that the possible worlds are constructed by taking the predicates and relations that obtain in the actual world and recombining them in individuals (or between individuals) so that states of affairs would have come out differently. In doing so he tries to avoid impossible combinations, avoids begging the question with the use of modal operators in the construction of possible worlds, as well as deal with some other theoretical problems, many of which would be regarded by some people as a trial in pedantry. There is also the explicit reliance on the notion of supervenience to avoid inflating the ontology.

Overall the theory at least has the right aim. I'm convinced that something like this theory is correct, or at least closer to correct than some of the running alternatives, including modal realism. My reason for thinking so is that I take seriously a rather simple, common observation: There is at least one way in which possible worlds do *not* exist; they are precisely what we talk about when we talk about what does not obtain (actually) and we are often explicit about the pretense in our conversations about possibilities. Moreover we seem to have no problem in identifying precisely what is fictional in our stipulated worlds and what it happens to have in common with the actual. Whether worlds of our imagining are possible or not seems, to me, to come down to whether their constructions are free of contradictions or else meet some yet stronger criteria of consistency. To my mind no theory is worth considering which does not have as a feature that possible worlds are distinct from the actual one in precisely their expressing states of affairs which do not actually obtain.

[Steve Levai · Rating 5 out of 5]

It was pretty sick, brah. so combinatorial. such fictionalism. wow.