iangb said:
Physicist here (though I don't presume to speak for all of us!).
Nor I for all philosophers.
iangb said:
Regarding the bolded, I wouldn't say it's quite accurate. Physics studies everything that exists physically and that we have evidence for - either physical evidence (detected directly or via machine) or as the consequence of a theory which has proven true in other situations (eg a black hole, which were studied by theory long before evidence for their existence was discovered). However, what physics does not do is study social/psychological phenomena, for which a link to the physical world has yet to be found - phenomena such as the concepts of 'conciousness', 'free will', 'God', 'love', 'democracy' or 'capital'.
I think this gets to the heart of my motive for posting this thread. I'm interested in public opinion about these matters, but professional opinion among philosophers is, if anything, even more fascinating to me. I've had a number of physicists tell me in private conversation that the notion that physics is epistemically complete (i.e. that if we know everything there is to know about physics, we would thereby know everything there is to know period) is questionable, at best. But many philosophers seem to advance it without the usual fear and trembling, which I find odd.
What I think is going on is that some philosophers seem to think that social and psychological phenomena will ultimately be reduce to physical phenomena. Physics is complete (so the story goes) because everything ultimately reduces to the subject matter of physics.
I'm not very convinced that this is so, however.
iangb said:
With that said, however, one of the most fascinating modules I did at university was called "Chaos and Complexity" The module looked at the staggering power of emergence - whereby simple micro-rules can lead to macroscopic phenomena which are both incredibly complex and hard to explain, and for which there is not an obvious link back to the micro-rules.
I have a question about this:
Is it the case that there is no obvious link because no such link exists
in principle, or is it only because we lack either the knowledge or computational or cognitive resources to establish the link?
In other words, for example, fluid dynamics is the study of how fluids behave. There are relations which describe how, say, water will flow over some object. What is in fact happening is that a gazillion water molecules are each moving over the object, but there's no way we could calculate a gazillion trajectories, and little point in doing so, since the relations we have describe the phenomena at a close enough approximation. Presumably, the behavior of the fluid is an emergent property of the beavhior of the gazillion water molecules. But in principle, we could build a computer powerful enough to calculate all those trajectories and have a fully worked-out reason why the fluid behaves as it does. The lack of an obvious link from micro to macro is caused by a lack of cognitive resources.
Similarly, one might say that the behavior of a spiral galaxy emerges from the behavior of many individual stars, nebulae, black holes, and so on. But in this case, in fact we lack knowledge, since apparent dark matter and dark energy play some role in that behavior, and we really don't have much idea what those could be. There's no obvious link from the macro back to the micro because we don't have the requisite knowledge.
On the other hand, it's possible to play the Game of Life on a stack of graph paper with a pencil. It takes a long time, but the various gliders and other patterns can be shown to be a direct result of the rules plus the starting conditions (and perhaps plus the presence of a conscious human observer). The emergent phenomena reduce neatly to those factors.
I'm not aware of another kind of emergence, though, and I've always wondered about this claim. There seems to be a strange kind of question-begging that often goes on. Some philosophers, for example, want to claim that consciousness emerges from the workings of the brain, but this happens in a non-nomic manner, so that working backward from consciousness to brain processes is simply impossible. But in the same breath, those philosophers want to insist that we
know that consciousness emerges solely from brain processes.
There may very well be something I'm missing, or a good example of emergence that I'm discounting unduly or something, of course.
iangb said:
As such, both interpretations are currently open. Either physical matter is all there is and phenomena such as conciousness are simply emergent phenomena from the insane complexity of the human brain, or there is something else which allows these things to exist and cannot ever be explained by physical means - a Descartian dualism or something similar. Physics has yet to either come up with the answer, or to meet and discover it's limits in the field.
This strikes me as correct, which is why I find the attitudes that some philosophers hold towards this argument a little odd.