In an ideal world, every extraordinary philosophical question would come with an extraordinary story telling the tale of how someone first thought of it. Unfortunately, we can only guess at what led a German philosopher, perhaps today best known for the Choco Leibniz biscuits later named after him, to come up with what is often described as the greatest philosophical question of all, namely: why is there something rather than nothing?
Many earlier thinkers had asked why our universe is the way it is, but Leibniz went a step further, wondering why there is a universe at all. The question is a challenging one because it seems perfectly possible that there might have been nothing whatsoever – no Earth, no stars, no galaxies, no universe. Leibniz even thought that nothing would have been “simpler and easier.” If nothing whatsoever had existed then no explanation would have been needed, not that there would have been anyone around to ask for an explanation, of course, but that’s a different matter.
Leibniz thought that the fact that there is something and not nothing requires an explanation. The explanation he gave was that God wanted to create a universe – the best one possible – which makes God the simple reason that there is something rather than nothing.
In the years since Leibniz’s death, his great question has continued to exercise philosophers and scientists, though in an increasingly secular age it is not surprising that many have been wary of invoking God as the answer to it.
One kind of answer is to say that there had to be something; that it would have been impossible for there to have been nothing. This was the view of the 17th century philosopher Spinoza, who claimed that the entire universe, along with all of its contents, laws and events, had to exist, and exist in the way it does. Einstein, who counted himself a follower of Spinoza’s philosophy, appears to have held a similar view.
Other scientists, such as theoretical physicist Laurence Krauss in his populist book “A Universe from Nothing” (2012), offer a more nuanced version of this answer to Leibniz’s great question. Krauss claims that our universe arose naturally and inevitably from the operation of gravity on the quantum vacuum, empty space teeming with virtual particles that spontaneously pop into existence before disappearing again. Krauss’s theory implies that there could not have been nothing because there has always been something: first there was gravity and the quantum vacuum, and out of that was born the universe as we know it.
Other theories in cosmology also seem to presuppose that there must always have been something in existence from which our universe arose, such as strings or membranes.
The trouble with such scientific answers to the question of “why there is something and not nothing” is that it is not clear why we should think that there had to be gravity, or the quantum vacuum, or strings, or even a universe at all. It seems entirely possible that instead of these things there could have been absolutely nothing.
Another response to Leibniz’s great question is simply to deny that it has an answer. The philosopher Bertrand Russell took this line in a famous radio debate in 1948. He was asked why he thought the universe exists, and responded “I should say that the universe is just there, and that’s all.”
On this account, the universe would be what philosophers call a brute fact – something that does not have an explanation. Russell’s point was not that humans hadn’t yet explained why there is something rather than nothing but that there is no possible explanation. Those who believe that our universe is part of the larger multiverse also take this line, suggesting that the multiverse – and hence our universe – has no ultimate explanation. Although it is now a popular response to Leibniz’s great question to say the universe is ultimately inexplicable, it does have the drawback of being intellectually unsatisfying (though of course that does not mean the response is false).
The most novel answer to Leibniz’s great question is to say that our universe exists because it should. The thinking here is that all possible universes have an innate tendency to exist, but that some have a greater tendency to exist than others. The idea is actually Leibniz’s, who entertained the thought that there may be a struggle for existence between possible worlds, with the very best one coming out on top as if through a process of virtual natural selection. In the end he did not accept the idea, and retreated instead to the more traditional view that the universe exists because God chose to make it so.
But the idea of a virtual struggle among possible universes has appealed to some modern philosophers, who have followed it to its logical conclusion and claimed that the possible universe with the greatest tendency to exist – which might be because it is the best, or because it contains some important feature such as the conditions that permit life to arise – will actually bring itself into existence.
According to this theory, our universe becomes actual not because God or anything else made it so but because it literally lifted itself out of non-existence and made itself actual. Weird? Yes. But we shouldn’t let that put us off. After all, an extraordinary philosophical question might just require an extraordinary answer.
Bottom line: Why does the universe exist?