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.cb CARTESIAN COUNTERFACTUALS


!!a1:	%2'If kangaroos had no tails, they would topple over'%1

seemed to David Lewis (1973, p.1) to mean something like this: in any
possible state of affairs in which kangaroos have no tails, and which
resembles our actual state of affairs as much as kangaroos having no tails
permits it to, the kangaroos topple over.

	Our proposed Cartesian treatment of ({eq a1}) is relative to an
informal and unstated mini-theory of the relevant aspects of the world.
Supposing that in this theory kangaroos have various attributes and so
does the world and that what happens to kangaroos depends on these
attributes, the theory tells us that kangaroos topple over when the
attribute of having a tail is negated.  This inference is possible,
because the theory has a Cartesian product structure, and whether an
object topples depends on its physical structure and not on other
components of the relevant aspects of the state.

	Compared to Lewis's treatment, the Cartesian treatment of
counterfactuals has disadvantages and advantages.  The main disadvantage
is that the meaning of counterfactual is relative to our theories.
Lewis attempts to avoid this, although theories may sneak back in
when the notion of "resembles" is defined.