What if...? Whether or not we live in the best of all possible worlds, the multiverse can help us make the best decisions in this one
WE LIVE in the best of all possible worlds. So said Gottfried Leibniz in 1709. For him, this was the only explanation for why a loving, all-powerful and all-knowing god tolerated evil. Any attempt to improve our lot would backfire, making it still worse. The world was not perfect, but optimal; and Leibniz was its first optimist.
His argument did not go unchallenged. Voltaire parodied it through the character of Doctor Pangloss in Candide, who clings to his Leibnizian optimism despite endless torments. But the idea endured and evolved: "The optimist proclaims that we live in the best of all possible worlds; and the pessimist fears this is true," wrote James Branch Cabell in 1926.
Now the question of possible worlds is back on the agenda. Fifty years ago, Hugh Everett decided that the neatest explanation for the oddities of quantum physics was that new universes were continually being created – each slightly different from our own. Many physicists now agree, with one even using it to again address the problem of evil (see "Multiverse me: Should I care about my other selves?").
Popular culture, too, has embraced the idea of parallel worlds, even if they are frequently depicted in ways that depart considerably from Everett. There's obvious appeal in what-ifs, and they aren't confined to science fiction: they feature in everything from romcoms (Sliding Doors) to thrillers (Fatherland).
What-if thinking has serious-minded uses, too. Historians use "counterfactuals" to probe key events: Winston Churchill was an early exponent. Companies use scenario analysis to evaluate how imaginary, but plausible, geopolitical events might affect them. And climate scenarios are critical in persuading negotiators to strike deals (see "Reasons to be optimistic about NY climate summit").
So should we make more use of the power of what-if thinking? The multiverse feels like a far-out concept, but it can nevertheless provide a useful framework for considering our decisions. And thinking about all possible worlds may help us to make this one the best we can. Perhaps there's reason to be optimistic after all.
This article appeared in print under the headline "The possibilities are endless"