Thank you all for an active and interesting forum. I enjoyed it.
I see the concept of consilience is alive and well. People tend to
recognize it as an important concept, and some people know what it means.
At least to them. The problem is that word has been understood in different
ways by different people from the very first day it was coined. In this
closing message, I will describe my own perception of how William Whewell's
concept was forever altered by John Stuart Mill and Charles Peirce.
Everyone recognizes that the greatest examples of scientific induction are
not like the examples of induction that Aristotle and Hume discussed: All
observed billiard balls have moved when struck; therefore all billiard balls
will move when struck. This simple-minded pattern of inductive inference,
known as simple enumerative induction, does not fit the famous examples such
as Newton's argument for universal gravitation or Perrin's argument for the
existence of atoms. The better examples have the noticeable feature that
the billiard ball example lacks: the conclusion of the inference postulates
the existence of something new, gravity, or atoms; something not mentioned
in the statement of the evidence that is cited in favor of the conclusion.
Nowadays, philosophers refer to these inferences as abductions (a word
coined by Peirce) or inferences to the best explanation.
The problem with inferences to the best explanation is that this notion is
mysterious until we are told what counts as an explanation, and what makes
one explanation better than another. The trouble is that different people
have different intuitions about what is explanatory. Cartesians refused to
accept Newton's theory was explanatory because it postulated instantaneous
action-at-a-distance. Today, many people refuse to say that quantum
mechanics is explanatory because it is provably inconsistent with common
cause explanation; that is, the postulation of local hidden variables.
Mill's response to Whewell was sensible on the surface. He wanted to
understand everything in terms of deduction, for this is a precise notion.
So, for him inference to the best explanation (if he had used that term)
would come down to deductive subsumption under general laws. Reconsider my
stock example. Let K stand for Kepler's laws applied to the moon, G be
Galileo's law projectile motion, and let N be the simple Newtonian model
that unifies these two phenomena by postulating the existence of gravity.
Mill's idea is that N is the better explanation than the conjunction K&G
because K and G are deductively subsumed under N. That is, N is a simpler
and more general law, and N entails K and N entails G. Unfortunately, it is
not the concept of deduction that is doing the work here. For K&G is more
general than either K or G, and K&G entails K and K&G entails G. The only
thing that differentiates N from K&G is the idea that N is "simpler and more
fundamental". But what does that mean? All Mill has done is to replace one
mystery by another.
The subsumption under general laws may be a necessary part of inference to
the best explanation. The objection is that it is not sufficient. We need
to say more. I think it is ironic that this something extra is exactly what
Whewell referred to as the consilience of inductions. Philosophers since
Whewell have attempted to demystify Whewell's consilience of inductions by
either ignoring it or by replacing it with something that is either
inaccurate or too vague (or both). While I don't deny that Whewell's
discussion of consilience is hard to understand in precise terms, it is
still be best discussion of the concept that exists today. If you think
there's something right about Whewell's idea, then you should study Whewell.
The following is an excellent collection of Whewell's writings on scientific
method:
Butts, Robert E. (ed.) (1989). William Whewell: Theory of Scientific Method.
Hackett Publishing Company, Indianapolis/Cambridge.
I recommend you begin with Whewell's essay "On the Fundamental Antithesis of
Philosophy" and then study Chapter III, which contains excerpts from Whewell's
Novum Organon Renovatum. Finally, Whewell's essay "Newton" is well worth
reading.
A word of caution though. Whewell was an eminent historian of science, and
in his philosophical writings he presupposes that you understand the
scientific examples in his terms. If you don't, then you will find yourself
in the same position as Mill and Peirce. Then, I predict that the cycle of
misunderstanding will continue.
Cordially yours,
Malcolm Forster
Professor of Philosophy
University of Wisconsin-Madison
http://philosophy.wisc.edu/forster
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Received on Mon Dec 6 18:53:31 2004
