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Phil Anderson (Nobel-prize winning physicist) wrote a thought-provoking take on emergence in "More is different" [1] talking about how interactions between coll

Phil Anderson (Nobel-prize winning physicist) wrote a thought-provoking take on emergence in "More is different" [1] talking about how interactions between collections of components can lead to emergent behavior that is qualitatively very different. Anderson was arguing against the reductionist perspective, and pointing out that emergent effects are as important (and worthy of being considered "fundamental") as reducing a system to its components. Thinking about it some more, I think that emergence is not something to be avoided, but embraced. Emergence is what gives rise to abstractions. Embracing abstractions is the reason we need compositionality -- the ability to translate from one level of abstraction to another, and glue together different abstractions/pieces [2]. If you didn't have emergent behavior, and all your pieces have the same level of abstraction, then there's not much structure to be exploited in how you combine them. Concretely, think of emergence as the reason why a function can become an atomic unit in a new effective description, even though it is composed of other units (statements/functions). [1] http://robotics.cs.tamu.edu/dshell/cs689/papers/anderson72more_is_different.pdf http://robotics.cs.tamu.edu/dshell/cs689/papers/anderson72mo... [2] John Hughes demonstrates how higher order functions and lazy evaluation are useful tools to glue together pieces, in "Why functional programming matters" -- https://www.cs.kent.ac.uk/people/staff/dat/miranda/whyfp90.pdf https://www.cs.kent.ac.uk/people/staff/dat/miranda/whyfp90.p...

3rdAccount 8y ago
I see what you're saying and think it makes sense in a physics context where things like cellular automata could represent some important aspect of mathematics/physics that we only barely understand. On the coding side I think abstraction has pros/cons. Yes it is nice to just use a module without really needing to peek behind the scenes, but there is an elegant way to abstract things (think of Linux commands as simple compiled applications that absorb and emit text that can be chained together with pipes versus the nodeJS leftpad fiasco. The latter showed that a lot of packages were just hacked together in a web. Again, contrast the original Smalltalk implementation of IDE, compiler, word processor, games, graphics, audio, networking...etc, that had a good bit of what Windows can do in 10k loc versus Windows which has an order of magnitude of additional code in just Microsoft Word alone. Clearly we've been abusing abstraction as these systems are beyond anyone's understanding when that doesn't need to be so. Chuck Moore of FORTH fame has a great interview where he points out that an OS is a non-thing that shouldn't be as critical as it is. I don't think he is 100% right, but he is onto something.
alimw 8y ago
Your second paragraph makes some startling claims. While it's not entirely clear to me what you mean by them, they do seem in conflict with my own understanding of emergence, and also with TFA, which says: > More generally, I claim that the opposite of compositionality is emergent effects. The common definition of emergence is a system being ‘more than the sum of its parts’, and so it is easy to see that such a system cannot be understood only in terms of its parts, i.e. it is not compositional.
- ssivark 8y ago
  Yes, the reason for my comment was to provoke more thought/discussion on that point. I don't understand the original claim that you've quoted.

3rdAccount 8y ago

I see what you're saying and think it makes sense in a physics context where things like cellular automata could represent some important aspect of mathematics/physics that we only barely understand. On the coding side I think abstraction has pros/cons. Yes it is nice to just use a module without really needing to peek behind the scenes, but there is an elegant way to abstract things (think of Linux commands as simple compiled applications that absorb and emit text that can be chained together with pipes versus the nodeJS leftpad fiasco. The latter showed that a lot of packages were just hacked together in a web. Again, contrast the original Smalltalk implementation of IDE, compiler, word processor, games, graphics, audio, networking...etc, that had a good bit of what Windows can do in 10k loc versus Windows which has an order of magnitude of additional code in just Microsoft Word alone. Clearly we've been abusing abstraction as these systems are beyond anyone's understanding when that doesn't need to be so. Chuck Moore of FORTH fame has a great interview where he points out that an OS is a non-thing that shouldn't be as critical as it is. I don't think he is 100% right, but he is onto something.

alimw 8y ago

Your second paragraph makes some startling claims. While it's not entirely clear to me what you mean by them, they do seem in conflict with my own understanding of emergence, and also with TFA, which says: > More generally, I claim that the opposite of compositionality is emergent effects. The common definition of emergence is a system being ‘more than the sum of its parts’, and so it is easy to see that such a system cannot be understood only in terms of its parts, i.e. it is not compositional.

ssivark 8y ago
Yes, the reason for my comment was to provoke more thought/discussion on that point. I don't understand the original claim that you've quoted.