Explanation: a scientific
explanation of an event or regularity is an argument that purports to
demonstrate why the event or regularity came to pass, given other features of
the world. Why was the outcome
necessary or probable in the circumstances and in the presence of relevant
governing laws or regularities?
The most general model of a scientific explanation is that of a
“covering-law explanation.” A
covering-law explanation is an argument consisting of one or more general laws,
one or more particular statements (boundary conditions), and deductive
derivation of a statement of the phenomenon to be explained (the
explanandum). Such explanations
are designed to show why the outcome was necessary in the circumstances, given
the initial conditions and the laws of nature. A covering-law explanation subsumes the phenomenon under the
general laws. A probabilistic
explanation has a similar logic.
Probabilistic explanations identify one or more statistical laws and
subsume the phenomenon under these laws: given probabilistic laws Li,
the probability of O is P. These
approaches to the logic of scientific explanation give primacy to the role of
scientific laws or laws of nature in explanation. On this approach, we have explained an outcome when we have
shown how it is necessary (or probable), given the relevant laws of
nature. A different approach to
scientific explanation proceeds from the point of view that the world is a
system of causal processes and mechanisms. On this approach, we have explained an outcome when we have
provided an account of the causal mechanisms and powers that led to the
occurrence of the outcome. Causal
explanations proceed by identifying causal mechanisms through which the initial
conditions brought about the explanandum.
The two approaches are related, since the presence of causal mechanisms
also implies the availability of lawlike generalizations that can function
within covering-law explanations.
But the causal mechanism approach comes closer to the intellectual task
of scientific explanation. We want
to know why the event occurred when we ask for an explanation of an
outcome. Ptolemy’s explanation of
the observed locations of the planets in the heavens proceeded on the basis of
subsumption of planetary motion under a set of lawlike generalizations (cycles
and epicycles). But the
explanation was unsatisfactory because it rested upon a false conception of the
causal processes that resulted in astronomical observations (geocentric rather
than heliocentric motion of the planets).
Achinstein, Peter. 1983.
The Nature of Explanation. New York: Oxford University Press.
Hempel, Carl. 1965. Aspects
of Scientific Explanation, and Other Essays in the Philosophy of Science. New York,: Free Press.
Kitcher, Philip, and
Wesley C. Salmon, eds. 1989. Scientific Explanation, Minnesota Studies
in the Philosophy of Science ; v. 13. Minneapolis: University of Minnesota Press.
Little, Daniel. 1991. Varieties
of Social Explanation: An Introduction to the Philosophy of Social Science. Boulder, Colorado:
Westview Press.
Miller, Richard W. 1987.
Fact and Method : Explanation, Confirmation and Reality in the Natural and
the Social Sciences.
Princeton, N.J.: Princeton University Press.
Salmon, Wesley C. 1984. Scientific
Explanation and the Causal Structure of the World . Princeton: Princeton
University Press.
Encyclopedia of
Social Science Research Methods, edited by Michael Lewis-Beck (University of
Iowa), Alan Bryman (Loughborough University), and Tim Futing Liao. Sage Publications.