It is something of a platitude that science does or ought to provide us humans more than mere
empirical data. Rather the ideal, it is so said, is for science to provide us with
knowledge. There are—of course—complications of nuance with any such bromide, but
nevertheless philosophers also like to ask, ensuingly, what scientific knowledge consists in.
Scientific knowledge: what is the real thing? One candidate is that science
explains
rather than merely
reports. That is, explanation animates scientific knowledge. But,
then, what is explanation?
Explanation is itself hard to explain. Many theorists have maintained that explanation is a matter
of giving answers to
why-questions. These differ from answers to other interrogations like
what-questions, which are largely the domain of reporting and description and
how-questions, which are the domain of engineering and artistry. But there are still
complications. For example, think about Jimmy McNulty, the homicide detective in David Simon’s
anti-hero in his series,
The Wire, standing over the corpse of man killed in a vacant
apartment building while next to a Baltimore coroner. They might question here
Why did this man die?
Both, in their own way, are scientists. But they seek different questions. And the answers
which will satisfy them, therefore, will naturally be different. Probably the coroner is asking
whether the man died of apoxia, whereas Jimmy asks
who murdered him.
In a coming work,
The Foundations of Microeconomic Analysis, I characterize what I
claim is the fundamental explanatory methodology of neoclassical microeconomics and, in particular,
general equilibrium theory. I call the methodology
analogical-projective explanation. The
explanatory regime is based on a more general epistemological phenomenon which I call a
deprojection. I focus here on what the actual mode of explanation rather than its
applications.
Both of these are terms of art, but there is really nothing new about them
other than the terminology. Analogical-projective explanation belongs to a family of theories of
explanation known collectively (and perhaps misleadingly) as deductivist theories. The term is
misleading because they are meant to cover explanatory methods like deduction
and
induction.
What do they have in common? All such regimes of explanation require that when someone is
explaining to you, say, what is so-and-so, that someone makes an
inference where so-and-so
is the conclusion. Why is the sky blue, you ask me? Here is a deduction which explains it: every
time light passes through a scattering medium, light is scattered in an inversely proportional way
to its wavelength. Every wavelength of light becomes more visible the more it is scattered. For all
visible wavelengths of the spectrum (i.e. those not including x-rays and television waves, etc),
the family of blue-violet has the shortest wavelength. The preceding three claims are what the
philosopher C.G. Hempel called universally-quantified natural laws (or laws of nature). When we add
the following plain assertion, that the sky is a scattering medium, along with the rules of the
predicate calculus, should yield the conclusion the sky is blue. In this case, the portion of the
deduction not including the conclusion serves as a explanation for the conclusion.
Such explanatory inferences can be carried out in other inferential systems. Outside of predicate
logic, Hempel spent much time focused on regimes of statistical inference for the purposes of
induction.
Figure 1. Some deprojectionists, surely. (Royalty-free. Vault Editions.)
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