Do Markov Blankets Give Us Real Neural Parts?

In my last post, I laid out what I think the rules are for developing a mechanistic model of the neural scale contribution to behaviour. I ended there with a question: what counts as a real neural part? How can we successfully decompose neural activity supporting a given perception-action loop into parts? 

In this post, I want to discuss one potential option: the hypothesis that Markov blankets, a key feature of the free-energy principle approach to neuroscience, can identify and pick out real neural parts. I'll discuss some recent ecological critiques of Markov blankets and some potential answers to the challenges.

Can the Free Energy Principle be made ecological? (Bruineberg et al, 2018)

Everyone loves Friston's free energy principle (FEP), and everyone wants it for their own. Not everyone can have it, though (well, at least not if it's going to mean anything) and so there's a spirited fight about who's theory it best fits in the literature. 

Bruineberg, Kiverstein & Rietveld (2018) argue two points in an effort to win the fight for the good guys. First, they want to show that inferential, representational takes on the FEP end up in an unworkable place. Second, they want to show that an ecological/enactivist analysis works much better. Overall I think they take a solid swing at both, so it will be interesting to see the responses this sparks. Here I want to review their arguments.

To unbury the lede, I like this paper a lot. It's really long and repetitive, but in here is an excellent ecological analysis of the free-energy principle that also works to explicitly rule out the competition. I am obviously biased, but their work pointing out the flaws of Hohwy's account all make good sense to me, not least because these flaws show up in all kinds of places in the representational ontology. Hohwy fails for the reason interface theory does, in my view, and it's nice to see separate analyses end up in the same place as me. 

For what it's worth, I am not yet convinced that the FEP is the way we need to go. However, if it ends up being a good idea, Bruineberg et al have done sterling work in showing how we should go about it. 

Free Energy: How the F*ck Does That Work, Ecologically?

Karl Friston has spent a lot of time recently developing the free energy principle framework as a way to explain life, behaviour and cognition; you know, biology, and it's become the cool kid on the block in fairly record time. 

Crudely, the basic idea of the FEP is that living organisms need to operate within a range for a given process, or else they will be malfunctioning to some extent and might suffer injury or death. Being within the relevant range across all your processes means you are alive and doing well, and so for an organism that has made it this far in evolution those states must be highly probable. Being outside those ranges is therefore less probable, and so if you find yourself outside a range you will be surprised. Your job as a self-sustaining organism can therefore be described as 'work to minimise surprise'.

There is a problem with this formalisation though. The information-theoretic term that formalise 'surprise' is not a thing that any organism can access, so you can't work to control it. Luckily, there is another formal quantity, free energy, that is related to surprise and is always higher than surprise. Free energy is therefore the upper bound on surprise and minimising that upper bound can reduce surprise as well. 

All this is currently implemented in an inferential, Bayesian framework that aligns, at least on the surface, with modern representational cognitive science. Andy Clark thinks this is the future, and Jakob Howhy has worked hard to nail this connection down so it won't move. If this is all right, and if the FEP is being successful, perhaps non-representational, non-inferential accounts like ours are going to lose.

A recent paper (Bruineberg, Kiverstein & Rietveld (2016) tries to wedge the FEP and Bayesian psychology apart to allow room for an ecological/enactivist take on the FEP. To be honest, I found the paper a little underwhelming, but it did get me thinking about things, and two questions have emerged.

Before we worry about an ecological account of the FEP, we need to know 1) whether such a thing makes any sense and 2) whether it adds anything new to the proceedings. All comments welcome - these are genuine questions and if there are answers we would love to know.