What are Symbols & Representations?
It
can be said that symbols are a kind of representation; even
though some symbols (or 'symbols' in inverted commas) can function - as in a computer - without having
any representational content (i.e., they rely on syntax alone). Of
course not all representations are model-like and they're certainly
not image-like. What matters is that they represent and that
representation (or symbolisation) can take many forms. (Models and
images clearly don't work that way.)
Just
as symbols can be connected to representations, so both are
intimately connected to computational models (or theories) of mind.
However, Tim van Gelder believes that the centrifugal governor
isn't representational. According to van Gelder, that also means that
“it cannot be computational”. (Or at the least it can't be seen
as computational if computations are seen as “rule-governed
manipulation[s] of symbolic representations”.) Yet “manipulable
representations lie at the heart of the computational picture”.
More broadly, according to the “[c]ontemporary orthodoxy”,
cognition is computation. Moreover, “the mind is [seen] as a
special kind of computer” in which “cognitive processes are [seen
as] the rule-governed manipulation[s] of internal symbolic
representations”.
One
basic point you can subtract from van Gelder is that his model and
the models he favours are simply more scientific – or biological –
than their rivals.
For
example, when he talks about his own preferred governor, its
ostensible superiority arises from the fact that
“the
states through which it evolves are not configurations of symbols but
rather numerically measurable arm angles and rates of change of arm
angle”.
Of
course one will immediately need to clarify why this is more
scientific or biological.
For
a start, symbols are created by persons: they aren't biological. In
that basic sense, the idea of there being symbols in the brain is
unscientific. (This isn't to say that the nature of human symbols
can't be treated scientifically.) Of course all this partly depends
on how literally the word 'symbol' is taken by philosophers of mind
and cognitive scientists. To some, it's taken literally and to others
it's taken metaphorically or analogically. However, the argument may
be that even when the use of the word 'symbol' is taken
metaphorically or analogically, it's still controversial from a
strictly scientific (or biological) point of view.
The
Representational Governor
Firstly
van Gelder offers us a governor that can indeed be seen in
representational or symbolic terms. All in all, this representational
governor is mechanically no different to the non-representational
governor. The difference is in how we theorise about it.
Indeed
take the case of the centrifugal governor's engine which elsewhere
van Gelder says shouldn't be taken representationally. This governor
(at least on the surface) is taken representationally.
Van
Gelder firstly goes into detail as to what this representational
governor actually does. He writes:
“The
very first thing it does is measure its environment (the engine) to
obtain a symbolic representation of current engine speed.”
These
representations, however, are simply means to a mechanical end. Van
Gelder continues:
“It
then performs a series of operations on this and other
representations, resulting in an output representation, a symbolic
specification of the alteration to be made in the throttle valve...”
The
basic point is that all this could be done without having
representations. More relevantly, it could all happen without us (on
the outside) seeing things in terms of representations. However, if
we do see things in representational terms, then we must also see
them in computational terms. That is, we will think that the
“computational” governor “literally computes the desired change
in throttle value by manipulating symbols according to a schedule of
rules”. After all that we'll have an “output”, which, in this
case, is the governor “acting on its environment”.
What's
happening here is that we're seeing the governor as some kind of
analog of both a computer and a mind. We see what van Gelder calls
the “computational governor” as a “device capable of carrying
out some set of basic operations (measuring, subtractings, etc.)”.
To
repeat, we can still say that there's no need for all this (mild)
anthropomorphism (or
symbol-fixation) because everything that happens is thoroughly causal
and mechanical and could happen just as it does happen without
representations or symbols. (This isn't to say that things with
symbols or representations can't involve causal processes.)
The
Centrifugal Governor & Cognitive Systems
So
far I've only talked about van Gelder's representational/symbolic
governor. However, all this is but a prelude to talking about human
minds or “cognitive systems”.
Here
it's not about “devices that transform symbolic inputs into
symbolic outputs”: it's about “complexes of continuous,
simultaneous, and mutually determining change”. In other words,
it's about the causal relations between the outside and the inside
(which, in this governor's case, can be numerically measured).
I've
just mentioned that this governor-talk is but a prelude to mind-talk.
In van Gelder's case, I should actually say
mind-body-and-environment talk. What we're talking about here
is “the nervous system, body, and environment”. That nervous
system, body and environment “are all constantly changing and
simultaneously influencing each other”. As a consequence of that,
van Gelder says that “the true cognitive system is a single unified
system embracing all three”.
The
“symbolic mind”, on the other hand, “interact[s] with the body
and the external world by means of the occasional static symbolic
inputs and outputs”. Here the representation or symbolisation of
the world - rather than the dynamical causal contact with it - is
paramount. When it comes to symbolic cognitive systems, the direction
seems to be all one way: from mind to world. With dynamical systems,
on the other hand, the causal arrow goes in both directions: from
world to mind and from mind to world.
Causation
Van
Gelder's model (or governor) simply doesn't rely on symbols or even
on representations. Instead what is emphasised are causal
interactions between the governor and its environment or between
parts of the governor and its other parts.
More
technically, in one passage there's talk of “numerically measurable
arm angles” and “rates of change of arm angle”. All this can be
seen within a strictly causal and non-symbolic (or
non-representational) framework. That is, the causal forces on the
governor's arms and the rates of changes of its arm-angles can both
be measured numerically.
All
that's being done here is the measurement of differences which have
been brought about by causal forces on the governor (or on parts of
the governor) by its other parts.
It's
true that it can now be said that numbers (or numerical measurements)
have taken the place of symbols or representations (at least in a
certain respect); though the numerical calculations don't symbolise
or represent what it is they measure – they simply, well,
measure it. What's being measured is literally the world's
causal impact on the governor and the causal impact of parts of the
governor on its other parts. In that respect, what's happening here
is simply applied physics. Nothing is being represented, symbolised
or even modelled.
Van
Gelder goes into more detail about his centrifugal governor and again
stresses its lack of reliance on symbols. More clearly, instead of a
system which utilises “configurations of tokens of symbol types”,
van Gelder's governor is a
“concrete
dynamical system made up of quantities changing in a way that
corresponds to the numerical sequences specified by the rule of
evolution”.
Here
again things are numerically measured rather than symbolised or
represented. Thus there should be nothing that's manifestly
problematic to a biologist or a physicist. (It will need to be
specified how to take van Gelder's reference to “the rule of
evolution”.)
Numerical
Measurements
I've used the phrase “numerical measurements” a few times so far.
Van Gelder borrowed this idea from what's called “dynamical
modelling”. Van Gelder says that this is a
“branch
of applied mathematics which attempts to describe change in
real-world systems by describing the states of the system numerically
and then writing equations that capture how these numerical states
change over time” .
To
put more meat on this bone, van Gelder says that
“Maxwell's
original dynamical analysis, and contemporary mathematical treatments,
all describe the arm angle and its role in the operation of the
governor in nonrepresentational terms".
Why
is that? The answer is simple: “the governor contains no
representations.” Again, the mathematics (or the numbers/equations)
neither symbolise nor represent – they simply measure.
Despite
saying that, van Gelder concedes that the arm angle (in the
centrifugal governor's case) can be seen as a representation of the
engine's speed. That is, there is indeed “some kind of correlation
between arm angle and engine speed”. However, just as it's often
said that “correlation doesn't equal causation”, so here it can
also be said that correlation doesn't equal representation.
Simply because there is a causal correlation between the angle (or
swing) of the arm and the engine's speed, that doesn't mean that it
represents the engine's speed. (Indeed couldn't this be
inverted by saying that the engine's speed represents the
angle of the arm even if the engine is, as it were, the “first
mover”?) However, surely it can be said here that it can be taken
as a representation if one wants to take it that way. A question
would still remain: What purpose would taking such things in
representational terms serve?
Conclusion
The
question is whether or not what van Gelder says about the mechanical
centrifugal governor can truly pass over to minds or to cognitive
systems. After all, it's clearly the case that machines like this
aren't representational. I suppose that van Gelder would say that's
the point in that even though the centrifugal governor isn't
representational it can still be taken that way. And it's that
representational factor which passes over to the mind or cognitive
systems. In other words, that's how many philosophers of mind and
cognitive scientists take cognitive systems and therefore how they
could take the centrifugal governor.
Again,
does it pass over? For a start, the centrifugal governor is far more
simple than the mind and of course it doesn't depend on a biological
brain. Nonetheless, none of that may matter for the point that van
Gelder is trying to establish. In other words, simply because the
cognitive mind depends on the biological brain (as well as being far
more complex than centrifugal governor), it doesn't automatically
follow from this that the brain-mind system is more likely to contain
and work upon symbols/representations than a mechanical device. In
fact complexity and biology (or lack thereof) may be irrelevant to
van Gelder's argument.
Reference
Van
Gelder, Tim, 'What
Might Cognition Be If Not Computation?', The Journal of
Philosophy, Vol. 92, No. 7 (July 1995).
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