The Elephant in the Brain: Hidden Motives in Everyday Life

by Kevin Simler

Here’s a thought experiment that might help. Imagine that every human being carries around a magical backpack full of tools. At any point, you can reach into your backpack and pull out a tool, and (here’s the magic) it will be copied as you pull it out, so the original gets to stay in the backpack. Every time you reach in, you get a new copy — but you can only get copies of tools you already possess. In this way, tool-sharing between backpacks works like information-sharing between brains: you can give something away without losing it for yourself. Now, suppose you meet up with an old acquaintance from school—let’s call him Henry—and the two of you start sharing tools with each other. Broadly speaking, you have two stances you can take toward Henry. You can treat him either as a trading partner or as a potential ally (whether as a mate or otherwise). If you’re looking to trade, you care mostly about the tools he can give you in any one exchange—specifically, the tools you don’t already own. But if you’re looking for an ally, you care less about the specific tools you receive from him, and much more about the full extent of his toolset—because when you team up with Henry, you effectively get access to all his tools. The ones he gives you during any individual exchange may be useful, but you’re really eyeing his backpack. And while you can’t look directly inside it, you can start to gauge its contents by the variety of tools he’s able to pull from it on demand. The more tool...