Interesting David Weinberger overview of the extended mind hypothesis.
The answer is that we assume that thinking is something we do in our heads. But this is not a natural idea. It has a long and well-known history, having received its definitive formulation in the 17th century by the philosopher Rene Descartes. It has become so ingrained in us that we now often actually experience thinking as an echo in our skull.
For almost 20 years, advocates of the “extended mind” theory have been providing an explanation that seems to me to be truer to our experience and more explanatory: We think out in the world with tools. This is distinctive of our species and helps to explain our evolutionary advantages. Other species use tools to do things. Only humans (as far as we know) use tools to think.
First proposed in the late 1990s by Andy Clark and David Chalmers, the extended mind theory has gained a fair bit of traction, with supporters applying it as far as they can.
For example, usually we assume that when a human does something in the world on purpose, she has an intention to do so, and that intention is something mental that the human brings to the engagement. If you are knitting a sweater or chipping a rock into an axe head, it’s because you have a mental intention to create a sweater or an axe. But some supporters of the extended mind theory argue that even intentions are not mental.
There is a great deal of academic debate about the validity of the extended mind hypothesis, but setting that aside, it is at least an interesting way to contextualize and consider how our thinking is influenced (and in same cases completely predicated upon) external objects.
