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Refutation of reductionism (excerpt from "The Fabric of Reality," by David Deutsch)
The whole title of this thread should read "Refutation of reductionism as a fundamental explanatory framework (excerpt from The Fabric of Reality, by David Deutsch)" but there wasn't enough room for that.
Anyway, I'm posting this as a general topic of discussion as well as to directly address arguments that hold that, for instance, an emotion like love is best, or most scientifically, viewed as "merely" the result of chemical reactions in the brain. With further ado:
The whole title of this thread should read "Refutation of reductionism as a fundamental explanatory framework (excerpt from The Fabric of Reality, by David Deutsch)" but there wasn't enough room for that.
Anyway, I'm posting this as a general topic of discussion as well as to directly address arguments that hold that, for instance, an emotion like love is best, or most scientifically, viewed as "merely" the result of chemical reactions in the brain. With further ado:
A reductionist thinks that science is about analyzing
things into components. An instrumentalist thinks that it is
about predicting things. To either of them, the existence of
high-level sciences is merely a matter of convenience.
Complexity prevents us from using fundamental physics to make
high-level predictions, so instead we guess what those
predictions would be if we could make them-- emergence gives us
a chance of doing that successfully-- and supposedly that is
what the higher-level sciences are about. Thus to reductionists
and instrumentalists, who disregard both the real structure and
the real purpose of scientific knowlege, the base of the
predictive hiearchy of physics is by definition the 'theory of
everything.' But to everyone else scientific knowledge consists
of explanations, and the structure of scientific explnations
does not reflect the reductionist hierarchy. There are
explanations at every level of hierarchy. Many of them are
autonomous, referring only to concepts at that particular level
(for instance, 'the bear ate the honey because it was hungry').
Many involve deductions in the opposite direction to that of
reductive explanation. That is, they explain things not by
analyzing them into smaller, simpler things but by regarding
them as components of larger, more complex things-- about which
we nevertheless have explanatory theories. For example, consider
one particular copper atom at the tip of the nose of the statue
of Sir Winston Churchill that stands in Parliament Square in
London. Let me try to explain why that copper atom is there. It
is because Churchill served as prime minister in the House of
Commons nearby; and because his ideas and leadership contributed
to the Allied victory in the Second World War; and because it is
customary to honor such people by putting up statues of them;
and because bronze, a traditional material for such statues,
contains copper, an so on. Thus we explain a low-level physical
observation-- the presence of a copper atom at a particular
location-- through extremely high-level theories about emergent
phenomena such as ideas, leadership, war and tradition.
There is no reason why there should exist, even in
principle, any lower-level explanation of the presence of
that copper atom than the one I have just given. Presumably a
reductive 'theory of everything' would in principle make a
low-level prediction of the probability that such a
statue will exist, given the condition of (say) the solar system
at some earlier date. It would also in principle describe how
the statue probably got there. But such descriptions and
predictions (wildly infeasible, of course) would explain
nothing. They would merely describe the trajectory that each
copper atom followed from the copper mine, through the smelter
and the sculptor's studio, and so on. They could also state how
those trajectories were influenced by forces exerted on
surrounding atoms, such as those compromising the miners' and
the sculptor's bodies, and so predict the existence and shape of
the statue. In fact such a prediction would have to refer to
atoms all over the planet, engaged in the complex motion we call
the Second World War, among other things. But even if you had
the superhuman capacity to follow such lengthy predictions of
the copper atom's being there, you would still not be able to
say, 'Ah yes, now I understand why it is there.' You would
merely know that its arrival there in that way was inevitable
(or likely, or whatever), given all the atoms' initial
configurations and the laws of physics. If you wanted to
understand why, you would still have no option but to take a
further step. You would have to inquire into what it is about
that configuration of atoms, and those trajectories, that gave
them the propensity to deposit a copper atom at this location.
Pursuing this inquiry would be a creative task, as discovering
new explanations always is. You would have to discover that
certain atomic configurations support emergent phenomena such as
leadership and war, which are related to one another by
high-level explanatory theories. Only when you knew those
theories could you understand fully (emphasis mine) why that copper atom is where it is.
In the reductionist world-view, the laws governing
subatomic particle interactions are of paramount importance, as
they are the base of the hierarchy of all knowledge. But in the
real structure of scientific knowledge, and in the structure of
our knowledge generally, such laws have a much more humble role.