Reference Material:
Emergence
by Mark Bedau + Paul Humphreys (2008)
My
initial approach to emergence, outlined in my previous post, finds a perfect
home among the views of contemporary philosophers. A discussion of these views
will help situate and refine my conception and lay a firm foundation for the
use of the concept in future investigations. Here we go.
A
great place to start is Mark Bedau’s distinction between three different types
of emergence (John Searle makes a similar distinction): nominal, weak, and
strong. Nominal emergence (Searle’s “emergent1”) is simply the notion that
certain properties or characteristics at the macroscopic level cannot be
possessed by the entities constituting the underlying microscopic level. Bedau’s
example is a micelle, a spherical conglomeration of lipids in which the
hydrophilic end is facing outward, the hydrophobic end inward. The permeability
of a micelle wall is a property that only the micelle can have. A single lipid
cannot have permeability – the concept is simply not defined for a single
molecule. Searle mentions solidity, liquidity, and transparency as examples
here. These are properties that only macroscopic materials can possess. They
are not defined for the atoms or molecules making up the materials.
Next
up is strong emergence (Searle’s “emergent2”). Strongly emergent properties
(entities, characteristics, etc.) are emergent properties that also have
irreducible causal powers – causal powers that cannot be explained by the
causal interactions of the microscopic parts. These causal powers typically
include the ability of the strongly emergent property to causally effect the
microscopic level, so-called downward causation. It seems this notion of
emergence is typically the one that enters conversations in the philosophy of
mind to characterize qualia, consciousness, etc.
Bedau
positions the concept of weak emergence between the nominal and strong
varieties. Weakly emergent properties are nominally emergent properties that
are only derivable from microscopic facts via direct simulation. The reference
to simulation makes weak emergence a kind of spectrum of concepts describing
properties that are variously derivable:
- without simulation in principle, but in practice, must be derived with simulation,
- by finite, feasible simulation only, and
- only by infinite or infeasible simulations.
With
this taxonomy of emergence in place, I can now stake out my position. My main
claim is basically that strongly emergent properties (entities,
characteristics, etc.) don’t exist. Bedau seemingly agrees with me, calling
strong emergence “scientifically irrelevant”, among other things. If my reading
is accurate, Brian McLaughlin and Jaegwon Kim also seem to agree. I won’t go
into exhaustive detail here. My point at the moment is that, at the very least,
the denial of the existence of this strong form of emergence at least has a
place at the table of philosophical respectability.
I
want to also sketch an epistemological view of weak emergence, as I hinted at
in my last post. This is where I stray from Bedau’s view, but my view is shared
by two other philosophers, Carl Hempel and Paul Oppenheim. Let’s say we have a
certain phenomenon that we think is weakly emergent, by which ever formulation
you like. The only way we can understand how this phenomenon comes about is by
directly simulating the microscopic dynamics of which it is composed and
observing the results. Then along comes some brilliant scientist who
invents/discovers a theory that allows us to predict the macroscopic phenomenon
without recourse to direct simulation. We now come to understand the phenomenon
as no longer weakly emergent, merely nominally emergent. In this way, the
status of some property as weakly emergent is relative to our best scientific
understanding.
