I have been reading a recently published book about the existence of all things

I have been reading a recently published book about the existence of all things (e.g. addressing the question, "Why is there something rather than nothing?"), and am struck by an interesting issue I see in the book and others like it. The author interviews philosophers (among other professionals) who often speak about the existence of things based on what one can imagine (e.g. one imagining something about possible worlds). It seems to me that there should be some kind of theory about how thoughts relate to the universe before anyone can conclude things about its nature. I know there are philosophers who have raised the question that the "laws" that govern thought/logic may be very different than the physical laws that govern the universe (and hence whatever theories we have about the world may be nothing more than our own ideas); so why is there such emphasis placed on imagination when discussing metaphysical issues? Why is the intelligibility of an idea about the universe (e.g. whether there are many universes) a criterion for determining the truth-value of the idea? Perhaps another way to say this is: why is the way we think about things somehow a true representation of how things are? Is it because this is about all we can ultimately do in philosophy (as opposed to, say, science)?

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