Some say “Philosophy has no relevance”. But one philosopher in particular has had measurable influence in a systemic way : David Kellogg Lewis.
In 1986, he penned, “On the Plurality of Worlds”, which has been cited not only in philosopher journals but also in many other fields.
What made “On the Plurality of Worlds” so special?
He put forth the notion that parallel universes are actually real, not in a quantum physics multiverse way, but in a “would/could/might” really *does* way.
The short of it is: It makes things simpler to deal with. It has pragmatic value.
For example: if you try to describe “how close to true” something is, with true meaning this universe we live in, by STARTING with the assumption that there are an infinite amount of real universes that are entirely separated – that is, no knowledge passes from one to another – you can simply talk about how many universes away from this one you are.
This is also known as “modal realism”.
In short, it is a concept that can make everything true and can simplify how we speak of truth.
Is it taken seriously? It is and it isn’t. Usually it’s used as a backdrop for criticism, as in, “And this is why David Lewis is wrong”, usually by the *other* big name in modern Philosophy, Kripke, who I don’t know much about. Actually, I don’t know much about much philosophy.
I just found this interesting. In the comments I’ll link to a paper which shows just how influential David Lewis has been both in and outside of the field of Philosophy.
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