I don’t understand. Consider the analogous statement: “The laws of physics are applicable to both X and Y, where X and Y are literally any two things in our universe. So the laws of physics are probably a bad starting point for understanding how Y works.”
Hmm, I guess it was a bit of cheap shot. But I think I was communicating something real, and disanalogous to what you wrote.
Specifically, everybody knows that both bacteria and humans have homeostasis, and that they maintain their bodily integrity under normal conditions etc. And FEP does not add any new information beyond that fact (cf. Section 1).
If you want to properly understand the human hypothalamus (for example), you should be aware that homeostasis is a thing! This is important background knowledge, albeit so obvious that one might think it goes without saying.
But it’s equally obvious that you cannot start with homeostasis and “derive” that the human brain has to look a certain way and do a certain thing. After all, bacteria have homeostasis too, and they have no brains at all.
Yet the FEP-adjacent discourse, in my experience, is full of claims (or at least suggestions) of that type: claims that we can start with FEP and derive all sorts of detailed contingent facts about how the brain is structured and what it does. But that can’t be right. It’s possible for a thing with homeostasis & bodily integrity to explore and model its surroundings, and it’s also possible for a thing with homeostasis & bodily integrity to NOT explore and model its surroundings. It’s possible for a thing with homeostasis & bodily integrity to turn on the light in a dark room, and it’s also possible for a thing with homeostasis & bodily integrity to NOT turn on the light in a dark room. Etc. Homeostasis & bodily integrity are just not enough of a constraint to get us to any of the interesting conclusions that people seem to ascribe to FEP in practice. And the applicability of FEP to bacteria is relevant evidence of that.
I don’t think the laws-of-physics discourse has any issues like that. The laws of physics are a ridiculously strong constraint. In fact, given initial conditions, the laws of physics are completely constraining. So when people say “X is a direct consequence of the laws of physics”, it’s probably fine.
Thank you for replying—and for the interesting post.
Your mention of homeostasis suggests an important conceptual distinction indicated by your discussion of feedback control systems. Basically, much of the interest in FEP among neuroscientists is due to the failure of concepts like homeostasis and feedback control to explain complex, dynamic, “goal-oriented” behavior. These concepts aren’t false; they just don’t work very well for some classes of interesting phenomena. It’s like pushing a car instead of driving it. You can get where you’re going eventually, you just wish you had some other way of doing it.
Perhaps an original post on the empirical situation leading up to interest in FEP and active inference would be useful, although I am not a historian and would undoubtedly give a summary more relevant to my background than to the modal neuroscientist.
I think the claim here is supposed to be that if the principle works for bacteria, it can’t tell you that much.[1] That’s true for your laws of physics example as well; nothing is gained from taking the laws of physics as a starting point.
That said, this doesn’t seem obviously true; I don’t see why you can’t have a principle that holds for every system yet tells you something very important. Maybe it’s not likely, but doesn’t seem impossible.
I know more about the brain than I do about physics, but I would hope that quite a lot is gained from taking the laws of physics as a starting point.
The fact that the FEP applies to both humans and bacteria (and non-living things like rocks, as Roman Leventov pointed out elsewhere), is valuable because, empirically, we observe common structure across those things. What is gained by the FEP is, accordingly, an abstract and general understanding of that structure. (Whether that is useful as a “starting point” depends on how one solves problems, I suppose.)
I think one important aspect for the usefulness of general principles is by how much they constrain the possible behaviour.
Knowing general physics for example, I can rule out a lot of behaviour like energy-from-nothing, teleportation, perfect knowledge and many such otherwise potentially plausible behaviours. These do apply both to bacteria and humans, and they actually are useful for understanding bacteria and humans.
The OP, I think, argues that FEP is not helpful in this sense because without further assumptions it is equally compatible with any behaviour of a living being.
This is a great line. Concise but devastating.
I don’t understand. Consider the analogous statement: “The laws of physics are applicable to both X and Y, where X and Y are literally any two things in our universe. So the laws of physics are probably a bad starting point for understanding how Y works.”
Hmm, I guess it was a bit of cheap shot. But I think I was communicating something real, and disanalogous to what you wrote.
Specifically, everybody knows that both bacteria and humans have homeostasis, and that they maintain their bodily integrity under normal conditions etc. And FEP does not add any new information beyond that fact (cf. Section 1).
If you want to properly understand the human hypothalamus (for example), you should be aware that homeostasis is a thing! This is important background knowledge, albeit so obvious that one might think it goes without saying.
But it’s equally obvious that you cannot start with homeostasis and “derive” that the human brain has to look a certain way and do a certain thing. After all, bacteria have homeostasis too, and they have no brains at all.
Yet the FEP-adjacent discourse, in my experience, is full of claims (or at least suggestions) of that type: claims that we can start with FEP and derive all sorts of detailed contingent facts about how the brain is structured and what it does. But that can’t be right. It’s possible for a thing with homeostasis & bodily integrity to explore and model its surroundings, and it’s also possible for a thing with homeostasis & bodily integrity to NOT explore and model its surroundings. It’s possible for a thing with homeostasis & bodily integrity to turn on the light in a dark room, and it’s also possible for a thing with homeostasis & bodily integrity to NOT turn on the light in a dark room. Etc. Homeostasis & bodily integrity are just not enough of a constraint to get us to any of the interesting conclusions that people seem to ascribe to FEP in practice. And the applicability of FEP to bacteria is relevant evidence of that.
I don’t think the laws-of-physics discourse has any issues like that. The laws of physics are a ridiculously strong constraint. In fact, given initial conditions, the laws of physics are completely constraining. So when people say “X is a direct consequence of the laws of physics”, it’s probably fine.
Thank you for replying—and for the interesting post.
Your mention of homeostasis suggests an important conceptual distinction indicated by your discussion of feedback control systems. Basically, much of the interest in FEP among neuroscientists is due to the failure of concepts like homeostasis and feedback control to explain complex, dynamic, “goal-oriented” behavior. These concepts aren’t false; they just don’t work very well for some classes of interesting phenomena. It’s like pushing a car instead of driving it. You can get where you’re going eventually, you just wish you had some other way of doing it.
Perhaps an original post on the empirical situation leading up to interest in FEP and active inference would be useful, although I am not a historian and would undoubtedly give a summary more relevant to my background than to the modal neuroscientist.
I think the claim here is supposed to be that if the principle works for bacteria, it can’t tell you that much.[1] That’s true for your laws of physics example as well; nothing is gained from taking the laws of physics as a starting point.
That said, this doesn’t seem obviously true; I don’t see why you can’t have a principle that holds for every system yet tells you something very important. Maybe it’s not likely, but doesn’t seem impossible.
I know more about the brain than I do about physics, but I would hope that quite a lot is gained from taking the laws of physics as a starting point.
The fact that the FEP applies to both humans and bacteria (and non-living things like rocks, as Roman Leventov pointed out elsewhere), is valuable because, empirically, we observe common structure across those things. What is gained by the FEP is, accordingly, an abstract and general understanding of that structure. (Whether that is useful as a “starting point” depends on how one solves problems, I suppose.)
I think one important aspect for the usefulness of general principles is by how much they constrain the possible behaviour. Knowing general physics for example, I can rule out a lot of behaviour like energy-from-nothing, teleportation, perfect knowledge and many such otherwise potentially plausible behaviours. These do apply both to bacteria and humans, and they actually are useful for understanding bacteria and humans.
The OP, I think, argues that FEP is not helpful in this sense because without further assumptions it is equally compatible with any behaviour of a living being.