Function, not material composition, is what distinguishes living things from non-living matter.

4:03even say about life there are at least some biologists who who say well maybe it's not even meaningful to talk about any difference between life and non-life but I I don't think that that's true uh and I think that the answer to the to the conundrum is to invoke function function is the thing that life has that non-life doesn't have. In other words, if we, you know, just to give you a

4:22little parable, if I were to come back from the future with this object and you ask me what it is, uh, and I tell you it is an artificial kidney with a 100red-year lifespan, you can implant it in a body and it'll it'll, you know, it'll work the way your kidneys do. It'll it'll filter ura from the blood and so on. Um, that's a really important piece of information, but it's not a

4:41material or a materialist piece of information. It's not something that you could read off from the atoms. uh and you know those atoms could be I don't know tungsten filaments or carbon nano tubes are made out of some technology we don't understand now or it could be organic it could be made out of uh cloned tissue um and and the point is that it working as a kidney doesn't

5:00depend on that matter there is a kind of separation of concerns between the matter and the function and so there's some real sense in which the function is like a spirit or like something like something immaterial it's not material and yet it also relies of course on the physics of what's going on you can't have the spirit without the matter as it were. So function is really important

5:21and uh and function is something that uh uh you know a rock on a non-living planet uh somewhere doesn't have. You know if you if you break a rock on a non-living planet you now have two rocks. You don't have a broken rock. Uh if you break a kidney you now no longer have a working kidney. That's the difference between something functional and something non-functional. This idea

5:41of function was formalized by Alan Turing who never intended the touring machine to actually be built uh when he wrote it in 1936. But there is one that was built by Mike Davyy in 2010. I don't need to review Touring machines with all of you of course um uh you you all know how they how they work. But I do want to review briefly uh Vonoman's update to

6:01Turring's thinking about computation uh which which he did a few years later. This was published postumously after Vonoman died. Um but the idea behind behind vonoman's thinking is he was trying to answer the same question that Schroinger had quite had asked in his what is life book. Uh and in particular he was trying to ask the question if you have a robot that is swimming around uh