Brian McLaughlin - Emergence and Supervenience (1997)
In terms of its subject matter, McLaughlin's second paper in the collection follows on chronologically from his first. In the wake of quantum mechanics and other modern scientific advances, he affirms that: "On the current evidence, it appears that all fundamental forces are exerted below the level of the atom". So, is it still logically tenable to appeal to truly "emergent" forces which are genuinely radically unexplainably from underlying processes?
Yes, is the result, though it's highly unclear that there actually exist any such forces. In brief, McLaughlin completes the hard work of the later Emergentists by formulating a rigorous definition of what it would mean to be truly, intuitively emergent:
If P is a property of w, then P is emergent if and only if (1) P supervenes with nomological necessity, but not with logical necessity, on properties the parts of w have taken separately or in other combinations; and (2) some of the supervenience principles linking properties of the parts of w with w's having P are fundamental laws.
Got that?
The magic lies in the use of "nomological necessity", which approximates to a semantic relationship of implication (if "the parts have property A" is true, then "the whole has property B" is true) rather than necessity through logical deduction (such as that of "all bachelors are male"); and the "fundamental laws" clause, which are akin to the Emergentist "configurational laws": that is, non-deducible first principles.
This definition is constructed through the use of the supervenience relation (see left), which sees wide use throughout analytic philosophy. To say that mental states supervene on neural states is to say that any change in mental state also entails (or, alternatively considered, requires) a change in neural state. Conversely, many neural states (labelled A on diagram) may potentially map to the same mental state (B).
So, there we go. Through this modal-logic scaffolding, emergence has been shown to be logically valid. However, McLaughlin himself is the first to admit that, even so, the only remaining known candidate for true emergence is consciousness - and this too is only left as an "open question". The resolution will come if it is ever revealed that the principles on which conscious states supervene are "fundamental" (i.e., in accordance with vitalism) or otherwise. My feeling is the latter.