My guest today is Annie Murphy Paul. Annie is a science journalist, and she has a new book out. It’s getting a lot of press. She’s made the rounds on all the Big Idea podcasts. I listened to a bunch of them in prep for this episode. Three of my favorites were her talks with Adam Grant, Ezra Klein, and Scott Barry Kaufman (fun fact: AMP was actually SBK's very first guest on his podcast). They’re all great discussions, and so I tried to broach some new territory with Annie in our talk here. The basic argument of her book is about fundamentally rethinking the way we talk about the mind. Her book is called The Extended Mind, and its starting point is a paper of the same title by two philosophers, Andy Clark and David Chalmers. The basic line of argument is that we tend to think of the mind as a fundamentally bounded entity, where the bounds of thought are essentially between one’s ears. These philosophers, Annie, and the relevant academic literature, are saying: No, actually when you start to scrutinize the assumptions of that idea, the position doesn’t hold up very well. Actually our minds are inextricable from the world around us. Annie’s book is all about diving into why this is the case, and how it should change the way we interact with our surroundings.In preparation for this discussion, I revisited that original Clark and Chalmers paper from 1998. The point of the paper, as they see it, is an argument against semantic externalism. This is a philosophical position about whether the “meaning” of a word resides in our heads, or in the world. Philosophers like Hilary Putnam and Tyler Burge advanced this externalist position, with the key soundbite being Putnam’s quote: “Cut the pie any way you like, meaning just ain’t in the head.” In particular, Putnam has this famous thought experiment, called Twin Earth, which him and his contemporaries use as an argument that internalism is false and externalism is true (meaning just ain’t in the head). Clark and Chalmers are kind of saying: Look, it’s not just meaning that isn’t in the head. It’s all of cognition. They call this position active externalism. There’s a quote from the paper I really love. This is Clark and Chalmers talking about the details of Twin Earth: “When I believe that water is wet and my twin believes that twin water is wet, the external features responsible for the difference in our beliefs are distal and historical, at the other end of a lengthy causal chain. Features of the present are not relevant: if I happen to be surrounded by XYZ right now (maybe I have teleported to Twin Earth), my beliefs still concern standard water, because of my history.” I have only a modest notion of what the hell they’re talking about. But I just love how the more sophisticated a philosophical argument is, the deeper it gets into the finer points of just how wet water on twin earth is, and if you were doused in it would it feel equivalently wet to substance XYZ, and how do you know whether it’s really you or twin-you who feels this wetness. At any rate, what Clark and Chalmers are saying is that our relationship to the people, objects, and tool in our external environment is not passive. We are actively thinking through the environment, as we much as are thinking through our own neurons. They give the example of Tetris and how you’re actually rotating the shapes on screen, then seeing if they fit—rather than thinking about how they might fit and then rotating accordingly.That’s a brief primer on the philosophical origins of this concept. In my conversation with Annie, we also talk about how our minds extend into our social surroundings, why writing is a form of memory, the important ideas about the extended mind that people tend to gloss over, how this concept should affect American education, and how this concept changes the way we think about other people. We also battle it out over whether a dual monitor computer set up actually works like a second brain. It was a fun conversation, and I hope you enjoy it.