Emergence in the philosophy of mind is one of the more popular positions on the contemporary philosophical scene, and I myself have strong sympathies towards it. I’ve considered it to be one of the very rare philosophical doctrines that gives appropriate weight to both philosophical as well as scientific ideas – an example being John Searle’s commitment to seeing consciousness and the mind in general as biological phenomenon (I’m not a naturalist myself but I do think his heart is in the right place.
In his outstanding book ‘Mind, Matter and Nature: A Thomistic Proposal for the Philosophy of Mind‘, James D. Madden identifies a serious problem for emergentism (drawing primarily on Searle as a general example of emergentism – there are plenty of different varieties, but Searle is helpful as a catch-all here)): the emergence of simple, subjective psychological states (he actually doesn’t see this as the main problem for emergentism – he takes the universal structure of thought to be the main problem – but I actually think this is a devastating objection).
Here’s the background. Madden identifies two ways in which we can give an account of something ’emerging’: either structurally or quantitatively:
‘First, consider a simple box composed of five sheets of plywood and some wood screws. Suppose that once constructed this box is used as a storage container for a basketball. Neither the sheets of plywood nor the screws have the power of containing a basketball independently of their composing a box, so the power of containment is an emergent feature…consider the example of a choir of small children. Each child sings quite softly, but the choir they compose is quite loud. This too might be a case of emergence, but it isn’t a result of the structural relation among the children or their voices…the properties of being loud is contained to a lesser degree in each of the parts of the system.’ (pp. 183-184)
Psychological states emerge in one of these two ways: either (1) structurally or (2) quantitatively. Psychological states are metaphysically simple (they can’t be broken down into smaller or more fundamental parts, and, following Searle, conscious states are irreducibly subjective and have a first-person ontology. So, then, here’s the first problem that Madden sees (and it should be noted that Madden sees this as the least serious problem – on his account, an emergentist could grant this objection and not suffer any serious loss): psychological states cannot emerge structurally because of their simplicity:
‘…one simply cannot derive metaphysical simplicity from complexity. At least as a matter of common sense, nobody doubts that a complex thing can come to be through the combination of distinct parts, but the issue here is whether something utterly simple could come to by combination. It seems that the various parts would have to make distinct contributions to the emergent entity, so there would be some division or distinction within such a thing; that is, the aspect or part of the simple entity to which constituent x contributes would be distinguishable from the aspect or part to which constituent y contributes.’ (p.186)
The second, and to my mind more serious, problem, is that given the definition of psychological states as irreducibly subjective – and for Searle, this is an almost absolute, qualitative distinction between conscious states and everything else – it’s almost impossible to see just how such states could emerge. Madden, drawing on Galen Strawson, points out that every analogy for emergence that’s typically used is a homogeneous analogy – water from H20 particles, magnetic fields, teams from players, etc. What is key here is that each of these emergentees/emergent properties is a quantitative emergence. Each of these things has, as it were, a potential for the emergent relation because the emergent entity/property isn’t qualitatively different from the emergent base. Madden points out the difficulty here:
‘…by Searle’s own admission such states (psychological states) have a property, that is, first-person perspective, that is utterly foreign to all of our concepts of ordinary physical objects; consciousness and ordinary physical objects certainly seem to be the most heterogeneous types of phenomena possible (they are fundamentally different kinds of phenomena): “The experiential/non-experiential [conscious/unconscious] divide, assuming that it exists at all, is the most fundamental divide in nature,” so to say that psychological states can emerge from neurophysiological states based on analogies proposed by Searle is rather strained. In none of the supposed cases of emergence are we dealing with radically heterogeneous phenomena, but that is exactly what we find in the consciousness/nonconsciousness case.’ (p.188)
The dilemma here is this: if (1) is the case, that is, if emergence is just a structural feature, then we can’t account for the simplicity of psychological states. Supposing we grant (1): if (2) is the case, we cannot account for the qualitative difference between consciousness and nonconsciousness. If we bite the bullet for (2) we are forced into pansychism – where everything has the potential for consciousness – or brute emergence, and if we opt for brute emergence, then (a) anything could be said to be emergent from anything if they were closely enough related and (b) brute facts would become a kind of deus ex machina or magic bullet. Taken on their own, (1) and (2) aren’t necessarily decisive, but taken together with the definition of psychological states (which seems to be a solid enough definition) there are serious problems here for an emergent account of psychological states.