> My benchmark of "this thing is well understood" is that it's possible to build that thing, or a replacement for it, again.
Something I've been thinking a lot about lately: Implicit in statements like this is the idea of a system. That some complex-seeming artifact is actually composed of a relatively smaller number of essential things and all of the observed complexity is just emergent properties of the simpler underlying system. Find the handful of hidden rules and you can build back up to the whole thing from first principles.
For example, if you were to learn chess purely by watching people play, it would be a huge struggle at first. Does how they hold the pieces matter? What role does timing play? Why does one player rest their head on their cheek while staring at the board? Eventually you start to figure out which actions are essential and which aren't. It doesn't matter where inside a square a piece is placed. All pawns are behaviorally equivalent, etc.
We really really like systems. So much so that we tend to assume everything is one. But I see no evidence to assume that biology and evolution work that. Evolution is a semi-random walk over the phenotype space and fitter organisms are discovered (mutated) entirely randomly. It may be that a kidney mostly filters blood, but also does a little of this other thing, and the fact that it pushes your small intestine out of the way is important, and also and also and also...
We can increase our understanding by learning more, but there may simply be no "first principles" for what makes an organism tick and almost all of its complexity may be irreducible. There may be absolutely no separation between "fundamental property" and "implementation detail". It may be that no terms in the grand equation of life cancel out.
Evolution is an incremental mechanism, which is to say that it preserves most of what it has previously done (DNA encoded) and just makes small changes on top of that. IOW it is essentially structure preserving, and any change that undoes anything that still has value is likely to be maladaptive and not preserved (as opposed to repurposing of gills into ears, etc, where the original function is not being used).
Of course evolution is also messy and isn't operating out of a playbook of decomposable single-function parts. Experiments with evolving electronic hardware have resulted in circuits taking advantage of all sorts of nasty non-linear analog effects, as you might expect.
Still, given the inherently incremental nature of evolution, it is highly likely to result in a system of parts operating with some degree of independence to each other. While there are still many aspects of the brain's functioning we don't understand, it's pretty apparent that it is composed of functional parts like this - cortex, hippocampus, cerebellum, basal ganglia, etc.
> but there may simply be no "first principles" for what makes an organism tick and almost all of its complexity may be irreducible. There may be absolutely no separation between "fundamental property" and "implementation detail". It may be that no terms in the grand equation of life cancel out.
But this is NOT true of all biology. I picked molecular biology as an example for exactly this reason. It’s driven by evolution with all its messiness, but yet it DOES have some reducible complexity. There really is DNA that is transcribed via certain molecules to RNA which is transcribed by other molecules into protein via a sequence of certain amino acids coded by the DNA base pairs. There is reducible complexity in spite of the crazy messiness of evolution, and it ends up looking a lot like some of our engineered systems in some instances (ie we can use the language of information theory and bits to describe encoding of genomes). We are able to use this to actually develop vaccines specifically using mRNA as a delivery mechanism, with specific, engineered changes to the transcribed viral protein spike to improve the vaccine’s effectiveness.
What I see in neuroscience looks a lot like genomics and inheritance before the discovery of DNA. And the insistence that “biological systems are entirely non reducible complexity” feels just a bit too much like a cop-out. This is not magic. If you are a neuroscientist optimistic about the field, then you must also believe there is some reducible complexity in there that will be discovered. I do get the feeling, based on research progress like in this article, that there really are some breakthroughs coming in really understanding what’s going on.
Something I've been thinking a lot about lately: Implicit in statements like this is the idea of a system. That some complex-seeming artifact is actually composed of a relatively smaller number of essential things and all of the observed complexity is just emergent properties of the simpler underlying system. Find the handful of hidden rules and you can build back up to the whole thing from first principles.
For example, if you were to learn chess purely by watching people play, it would be a huge struggle at first. Does how they hold the pieces matter? What role does timing play? Why does one player rest their head on their cheek while staring at the board? Eventually you start to figure out which actions are essential and which aren't. It doesn't matter where inside a square a piece is placed. All pawns are behaviorally equivalent, etc.
We really really like systems. So much so that we tend to assume everything is one. But I see no evidence to assume that biology and evolution work that. Evolution is a semi-random walk over the phenotype space and fitter organisms are discovered (mutated) entirely randomly. It may be that a kidney mostly filters blood, but also does a little of this other thing, and the fact that it pushes your small intestine out of the way is important, and also and also and also...
We can increase our understanding by learning more, but there may simply be no "first principles" for what makes an organism tick and almost all of its complexity may be irreducible. There may be absolutely no separation between "fundamental property" and "implementation detail". It may be that no terms in the grand equation of life cancel out.