There is at most one world (Donald Davidson)
In ‘On the Very Idea of a Conceptual Scheme,’ Donald Davidson makes the following assertion: ‘there is at most one world’ (1984: 187). Davidson does not explicitly argue for this assertion, but here is a suggestion as to what his reasoning against multiple worlds is.
There can only be more than one world, if there can be two worlds.
Assume that there are two worlds, A and B.
The content of any world is all that there is.
So the content of world A is all that there is.
And the content of world B is all that there is.
So world A and B are identical in content.
There are only two worlds if they are not identical in content.
So A and B are not two worlds.
So we must reject the assumption that A and B are two worlds.
So there cannot be two worlds.
So there is at most one world.
Regarding the premise that the content of any world is all that there is, Davidson might say that one can only sensibly reject this premise by operating with a different sense of the term ‘world’ to the one which he is using. In this sense, ‘world’ means the same as ‘reality’.
Davidson, D. 1984. On the Very Idea of a Conceptual Scheme. Reprinted in Inquiries into Truth and Interpretation. Oxford: Clarendon Press.