Reduction and Elimination in Philosophy and the Sciences

Making the Mind Higher-Level
Elizabeth Schier, Sydney, Australia
Central to Kim’s position is a distinction between levels
and orders. Levels are understood in mereological terms.
Lower-levels contain parts which are organised into
structured wholes at higher-levels. Orders are ways of
conceptualising properties without providing details of their
various realisers. So water is at a higher-level to the H20
molecule because water is made up of H20 molecules.
Liquidity is at a higher-order to water because water is one
way to realise liquidity. But liquidity is not at a higher
mereological level to water because water is not a part of
liquidity in the same way that H20 molecules are a part of
water.
Crucially Kim is a realist and a physicalist about
higher-level phenomena. He is a realist because higherlevel
properties have causal powers that their parts lack.
He is a physicalist because the properties of the higherlevel
wholes are determined by their mirco-physics
constituents. A brief reflection on a simple example shows
that this is obviously correct. Water can do things that no
individual H20 molecule can: you would not want to dive
into a pool containing only one H20 molecule. This
difference in causal powers is due to the arrangement of
the molecules: you also would not want to dive into a pool
containing ice or steam. The fact that the isolated
constituents or the same constituents in different structures
can have different types of causal powers means that the
different structures can not be identical to their
constituents. There must be more to being water, snow, or
ice than being composed of H20 molecules. But the extra
thing is simply the arrangement of the parts. Importantly,
the ways in which the parts can be arranged depends on
the nature of the parts. It is the because oxygen is a small
highly electronegative atom that H20 is a polar molecule
and it is because H20 is a highly polar molecule that
hydrogen bonds form between the molecules and it is
because hydrogen bonds form between the molecules that
water has unusual properties (e.g. liquid water is denser
than ice so ice floats on water). The nature of the H20
molecule determines how it can be arranged and therefore
determines the causal powers of the structures that are
composed of it. So it is the nature of the constituents that
determines the causal powers of the whole. According to
Kim, although physicalism is true, a strongly eliminative
micro-physicalism is clearly false. Although everything is
physical, not everything is identical to the entities of microphysics
because not all the causal powers are possessed
by the entities of micro-physics.
While there are controversies regarding Kim’s
picture, they do not concern his claim that higher-level
phenomena are real and physical. No one doubts that
water can do things that an individual H20 molecule can’t
and no one doubts that water is physical. This suggests
that if we can show that the mind and brain are in a
mereological relationship in the same way as water and
H20 then we can show, to everyone’s satisfaction, that the
mind is as real and physical as water. I want to suggest
that this option has not been explored because the
standard, classical digital account of the mind does not
make the mind higher-level. Fortunately, a connectionist,
analog account of the mind does.
What might distinguish the mind from its lower-level
constituents? What might the mind be able to do that its
parts can’t? One obvious answer is that the mind can
compute, but its parts can’t. So what would it take for
computation to be a higher-level property? What is doing
the causing in computation? Following O’Brien and Opie
(2006) I suggest that computation is a causal process
involving representing vehicles where the trajectory of that
process is shaped by the meaning of the vehicles. That is,
computation involves representing vehicles causing each
other in a way that depends on the meaning of those
vehicles. Meaning is doing the causing in computation. So
for computation to be a higher-level process we need
meaning to be higher-level property. That is, we need the
meaning of a representing vehicle to depend on the
organisation of its parts. Although we can get this for
analog computation, we do not get this for digital
computation. 1
Digital computation is the rule-governed
manipulation of symbols (Haugeland 1985). A symbol is a
representing vehicle that bears an arbitrary relation to its
represented object (Copeland 2005). The content of a
symbol does not depend on the intrinsic nature of the
symbol. For example there is nothing about the numeral ‘3’
as a physical object that means it must be about the
number three. Another way to put this is that there is an
arbitrary relation between the syntactic and semantic
properties of a symbol. This means that, for symbols,
meaning is not a higher-level property of the symbol. The
meaning of a symbol does not depend on the organisation
of the parts of a symbol. You can change the structure of
your symbol, and as long as the rules are changed to
recognise the new structure, the system will still function
correctly. This is why it is possible to build a digital
computer out of anything, even beer cans or bricks.
But there is an alternate analog account of
computation according to which computation is the
manipulation of analogs, representing vehicles that
resemble what they are about. Consider for example an
architect’s scale model, which is being used to calculate
the shadows that will be cast by a building. 2 Like water, the
organisation and nature of the parts of a scale model
matter. If you change the structure then you change what
they are about. For example, if you move the buildings,
then they will no longer represent the proposed buildings
and the shadows they will cast. If you change the nature of
the constituents you also change the meaning. It is no
good building your scale model out of glass because it
won’t block the light in the right way. The organisation and
nature of the constituents determines what the model
resembles and therefore determines what it represents. In
analog computation there are no rules which we can
change to deal with the change to the representing
vehicles. The meaning of the representing vehicles in a
scale model is at a mereologically higher-level to their
constituents. The same constituents in a different
arrangement will have a different meaning. Even by Kim’s
standards, meaning is a new, causally efficacious property
in the scale model.
1 The analog-digital distinction is often understood in terms of the continuity or
discreteness of the representational medium. I am using the distinction not in
this way, but rather as a distinction between representing vehicles that do or
do not have their content grounded in resemblance (see Copeland 2005).
2 I have taken this example from Gerard O’Brien.
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