The final claim for there being an ontological sense to emergence is “downward causation“, a phrase coined by the evolutionary epistemologist Donald Campbell in the 1970s. The idea here is that emergence is real because higher-level (or bigger, composite) entities cause changes in the properties and dynamics of their parts. This is very big in the philosophy of mind. It is also often used by a certain kind of systems thinking in physics. Recently, Sean Carroll took it to task.
This view requires a mode of thinking sometimes called “hierarchy theory”. It is roughly this: the world is comprised of objects organised in a hierarchy: subatomic particles form atoms, atoms form molecules, molecules form monomers, monomers form polymers, polymers form cells, cells form organs, organs form organisms, organisms form societies, societies form economies, etc. It’s a very neat way of conceiving of the world. And, if not actually always false, it’s usually false. Some molecules only form molecules (molecular water is far more common than fluid water, although not on earth). Some cells, well actually the bulk of cells, form single celled populations and little more, although many form biofilm communities. And so on.
Hierarchy theory was a needed correction at a time when reductionists were being atomistic, back in the 60s. But like any spice, as Kierkegaard remarked, you cannot make a meal of it. And even if some things are arranged in mereological hierarchies, it doesn’t follow there is only one such hierarchy. For example, there are protein complexes both inside and outside cells. I do thinking with both my little grey cells (as Poirot would call them) and also my iPhone, Mac and Google. Hierarchy theory is largely an echo of the Great Chain of Being, but that’s another post for another day.
So what does the claim there is downwards causation consist of? A simple formulation is by Bernd-Olaf Küppers: “The whole determines the behaviour of its parts” (Küppers 1992:243). That is to say, the causal arrow points from larger or organised whole to part. We can diagram these:
Causation occurs at higher, lower and intra levels. So if the higher level is mind, and the lower level is brain, then mental events can change the behaviours of the brain, as well as vice versa and between level events. By contrast, the reductionist account has causation at some lower level only:
On at least one account, higher level causes aren’t really causes at all, but just relations between what are themselves just compositional objects and apparent processes. A mental even cannot cause brain processes to change behaviour because it has no causal power that is not simply a composition of the underlying (physical) processes. What looks like downward causation is just lower level causation of both the whole and the part. If my fear causes me to express more adrenaline, it is because both fear and adrenaline production are physiological (and hence physical) processes.
Notice that I did not say “just” physical. If everything is physical, then dismissing the phenomena as illusory is unnecessary and prejudicial. A mountain may be composed of rocks and ultimately subatomic particles and fields, but understanding that doesn’t mean I don’t have to go around or over it to get to the other side.
Emergentism of this kind (there are several) is unlovely, philosophically, as it has way more causal arrows than are needed. Or does it? Our intuitions are that what happens at the higher level do in fact influence what happens at the lower, and so things like “temperature” causes molecules to move about more rapidly. I think what happens here is that an explanation moves downwards, but only because we have hypostatised (thing-ified) an abstract term. It’s very little more than definition. But causation, if it occurs at all, occurs at the “lowest”, which is to say, the physical, “level”.
So now the question is what that level is. As a physicalist, I of course think it is physical, but since our best physics is not yet right, I can’t say that it is actually at the level of the particle zoo as now understood, and so on. It doesn’t really matter, though. I presume (thus making a pres out of u and me) that we will one day unify physics into a universal theory. I doubt greatly that it will turn out to be all that different to our best modern physics. But even if it were, the question concerning emergentism is whether or not we can reduce other theories to other theories than physics nearly all the time. We do not attempt to reduce psychology to physics (yet!) but to biology. So whether or not we unify physics, now or later, we can still usefully be reductionists.
I said before that to be a reductionist in biology is akin to being a baby-eating robber baron. This particularly played out in the sociobiology debates of the 70s. It need not have. While we may object to genetic determinism, we can hardly equate that with biological determinism. I can think (indeed all the evidence points there) that we are what we are because our biology makes us and still allow for environmental determinism because biology always has a context. But be determinists we must: it is identical in intent if not terminology to saying that things have natures, which is the foundational view of science itself. We act according to our natures, just as God is supposed to, and most of our moral theorists have argued for two thousand years. To think otherwise is to deny the possibility of knowledge.
I know that people want to preserve our specialness, especially our mental specialness, but if wishes were horses then beggars would ride. The world is not required to match our desires, despite what Oprah would have you believe. An ancient doctrine (“as above, so below”) of the alchemists had it that we do what we do because we mirror the intentionality of the universe – in fact it is the precise reverse. We presume the world is like us. But we are like the world, and just as unintended and as determined as everything else.
Reductionism, or rather than variety of it known as physicalism, makes the best case for understanding the world, including ourselves. Emergentism of the strong, ontological, variety is mysticism. Wholes are more than the sum of their parts precisely because they have structure that the parts, by definition, cannot have. Allow reduction to include spatial, causal and temporal relations, and you get everything you need. You just don’t get that specialness we so ardently desire. And so what?
The virtue of post-Baconian science is that final causes were abandoned, except (and this is often overlooked in the rhetorical flourishes of this old debate) where you have a system capable of projecting goals and seeking them. And these systems (which you may gather includes humans) also call for an explanation: how can systems seek goals? The answer is fairly simple. They do so because their ancestral systems did so, only perhaps less well. There is nothing special about these systems in an ontological sense – they are just composites of less complex systems, and have degrees of freedom that the parts don’t have. A wheel will not win the Indianapolis 500; a car can. That doesn’t mean “car-ness” is a novel ontological category that causes wheels to turn and follow race tracks.
I have rambled somewhat, largely because I don’t intend to publish this, but to stimulate debate. So, you strong emergentists, make your case. Why should we think that emergence is anything other than the point at which our expectations and computational capacities are exceeded? Why believe in downward causation? Don’t trot out the old intuitions and examples, but defend yourselves. For now, I see no need to move beyond physics. In the end science will reduce everything directly to physics – no layer cakes here. We have warrant for this, based on the past. Sure, we may one day meet something that can never be so reduced, but we haven’t yet.
This also goes to the question I asked a while back: what are the domains and disciplines of science? I will ask this again in a new post.
Beckermann, Ansgar, Hans Flohr, and Jaegwon Kim. 1992. Emergence or reduction? Essays on the prospects of nonreductive physicalism. Library ed, Foundations of communication and cognition = Grundlagen der Kommunikation und Kognition. Berlin; New York: W. de Gruyter.
Campbell, Donald T. 1974. “Downward causation” in hierarchically organized biological systems. In Studies in the philosophy of biology, edited by F. J. Ayala and T. Dobzhansky. London: Macmillan:179-186.
Küppers, Bernd-Olaf. 1992. Understanding Complexity. In Beckermann et al. :241-256.