Possible Worlds – From Leibniz to Lewis to Seth

Possible worlds is a philosophical theory that all worlds that could possibly exist do in fact exist. This is an interesting and difficult theory to prove (or disprove, for that matter).

The philosopher and mathematician (he and Isaac Newton independently invented calculus) Gottfried Wilhelm Leibniz (1646-1716) is famous for saying that we live in the best of all possible worlds. Does this mean that there are other worlds coexisting with ours? Perhaps, but not necessarily. Leibniz believed that God created this best possible world, so why should the Creator also have created a bunch of lesser worlds, presumably uninhabited?

Leibniz is unlikely to propose anything resembling the modern theory of possible worlds. For this, we have to look at contemporary philosophers, like David Lewis, who is the founder of modal realism. While it would be impossible to do justice to such a complex theory in a short article, we can lay out some of the basic ideas of modal realism.

According to Lewis and other possible worlds advocates, possible worlds are exactly what the term sounds like. Any world that is logically possible is as real as ours. This rules out anything that isn’t logically possible, such as a world where 1+1=5. So the theory of possible worlds does not violate any of the natural laws that we take for granted. It simply (or perhaps not so simply) posits that whatever can be, is.

One of the problems with the study of modal realism is that it is often overshadowed by different, somewhat similar, better-known theories. On the one hand, we have the many worlds or multiverse theories of quantum physics, which approach the problem from a completely different perspective, trying to prove the existence of alternative dimensions through mathematics and physics.

Philosophers, on the other hand, tend to use semantics and language heavily in making their case. The theory of possible worlds goes back to some problems in the philosophy of language, in which, according to some accounts, it is impossible to affirm the non-existence of something. For example, consider the statement “Unicorns don’t exist.” Well, what is a unicorn? To answer this, we must have an image or concept of a unicorn in our mind, so this means that unicorns, in a sense, must exist! Now, of course, the sane (ie non-philosophers) will object that unicorns are *mythical* animals, so we can describe them and have pictures of them in our heads, but they don’t exist yet. Ultimately, this is a never-ending argument, but the philosopher with a “possible worlds” bias will argue that what we can conceive of does exist.

Consider the possible existence of a square circle; that is, a geometric shape that is both a square and a circle. While this “object” can be named, it cannot actually be meaningfully imagined, drawn, or thought of, because the idea itself is impossible. So square circles don’t inhabit any possible worlds, while unicorns probably do.

Aside from physics and philosophy, there are also new age channelers and metaphysicians who believe in somewhat similar concepts. Channeler Jane Roberts wrote a series of books in the 1960s and 1970s supposedly channeling “Seth”, a being from higher dimensions. Seth describes in great detail how we live in a multidimensional universe. He speaks of “probable selves” and “probable worlds,” which are analogous to possible worlds. Other metaphysical writings have been expounded on this.

Interestingly, of the three, it is the new age or metaphysical perspective that attempts to make the theory of possible worlds more practical. While physicists try to test their theories with experiments involving particles and philosophers debate semantics, the metaphysical viewpoint suggests that we can access alternate worlds through the right approach, meditation, or spiritual process. This isn’t to say it’s that simple, but at least it gives you something to work with.

Possible worlds is one of those extremely attractive theories that is very difficult, if not impossible, to test. This seems to imply that there is no possible world where the theory of possible worlds can be tested, haha. Along with time travel and reincarnation, it’s something that can be comforting and fascinating to explore even without evidence. I say comforting because it suggests a universe with infinite possibilities, where hopefully we can learn to choose which world we want to inhabit.