Every pure mathematician has experienced that awkward moment when asked, “So what’s your research good for?” There are standard responses: a proud “Nothing!”; an explanation that mathematical research is an art form like, say, Olympic gymnastics (with a much smaller audience); or a stammered response that so much of pure math has ended up finding application that maybe, perhaps, someday, it will turn out to be useful. That last possibility is now proving itself to be dramatically true in the case of category theory, perhaps the most abstract area in all of mathematics. Where math is...

If greed is good, as Gordon Gekko proclaimed in the 1987 movie Wall Street, then economics ought to be a superlative science. After all, at the core of economic theory sits a greedy idealization of human nature known as Homo economicus. It’s a fictitious species that represents the individual economic agent, motivated by selfishness. H. economicus is completely rational, by which economists mean it’s out for itself. And selfishness is supposedly the smart strategy when competing for the resources needed to survive. As Gordon Gekko also mentioned, greed “captures the essence of the evolu...