There's an idea in philosophy that some of us use when we are talking about possibility: Possible worlds.
A possible world is a world that's like this one, but maybe a bit different. So we might talk about a possible world where I didn't buy a shirt from @steemitshopaus (and am sad because of it), or a possible world where the US has a different president. Some possible worlds might seem less likely - like the one where my backyard is full of circus clowns killing each other with crossbows. And some worlds might be impossible - a world with four-sided triangles or macro-level propositions can both be true and not true at the same time.
David K Lewis, in writing about possible worlds, held the rather controversial view these worlds are just as real as ours, a position known as modal realism. He argued that our 'actual' world is just the one we happen to be in, and that it's like saying 'here' to denote a certain place in space, and 'now' to denote a certain place in time.
Under his account, there can be no interaction between possible worlds because a possible world is defined by "spatiotemporal interrelations of their parts" (1986, p. 70)- that is the broadest relation that things can have in time and space and he held that causal relations had to occur in time and space. Thus if there is any chance things can interact, they must, by Lewis's definition be worldmates.
The puzzle that occurred to me is this: If I think about another possible world, and this consideration causes me to make a decision one way or another, has that possible world not somehow caused a change in this world? Let's say, hypothetically, that I was sick of being an underpaid casual academic, and was considering to cash in on Australia's bloated property market by becoming a real-estate agent. I think about a possible world where I decide to give up on philosophy and go into real-estate, and decide that it looks like a world I probably wouldn't enjoy. On the basis of this analysis, I decide against this particular change in career in the actual world. That possible world has not played any direct causal role, and yet, that I can think about it as a possible world has changed this world.
Of course, rather than postulating some sort of non-physical , cross-world,'spooky action at a distance' type of thing, I could just put it down to me using my imagination, and admit that thinking about possible worlds involved no interaction whatsoever between me and those worlds. Still, I can't help but wonder if there's a mystery here to be solved.
Thanks for reading. Please upvote me in this actual world, rather than my counterpart in some other possible world.
Custom footer by @bearone Photo by Sweet Ice Cream Photography on Unsplash