Explanatory power is the ability of a
hypothesis
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...
or
theory
A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be ...
to explain the subject matter effectively to which it pertains. Its opposite is ''explanatory impotence''.
In the past, various criteria or measures for explanatory power have been proposed. In particular, one hypothesis, theory, or explanation can be said to have more explanatory power than another about the same subject matter
* If more facts or observations are accounted for;
* If it changes more "surprising facts" into "a matter of course" (following
Peirce);
* If more details of causal relations are provided, leading to a high
accuracy and precision of the description;
* If it offers greater
predictive power
The concept of predictive power, the power of a scientific theory to generate testable predictions, differs from '' explanatory power'' and ''descriptive power'' (where phenomena that are already known are retrospectively explained or describe ...
(if it offers more details about what should be expected to be seen and not seen);
* If it depends less on authorities and more on observations;
* If it makes fewer assumptions;
* If it is more
falsifiable (more
testable
Testability is a primary aspect of Science and the Scientific Method and is a property applying to an empirical hypothesis, involves two components:
#Falsifiability or defeasibility, which means that counterexamples to the hypothesis are logicall ...
by observation or experiment, according to
Popper).
* If it can be used to compress encoded observations into fewer bits (
Solomonoff's theory of inductive inference)
Recently,
David Deutsch
David Elieser Deutsch ( ; born 18 May 1953) is a British physicist at the University of Oxford. He is a Visiting Professor in the Department of Atomic and Laser Physics at the Centre for Quantum Computation (CQC) in the Clarendon Laboratory of ...
proposed that theorists should seek explanations that are ''hard to vary''. A theory or explanation is hard to vary if all details play a functional role, i.e., cannot be varied or removed without changing the predictions of the theory. Easy to vary (i.e., bad) explanations, in contrast, can be varied to be reconciled with new observations because they are barely connected to the details of the phenomenon of question.
Examples
Deutsch takes examples from
Greek mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities ...
. He describes how very specific, and even somewhat falsifiable theories were provided to explain how the god
Demeter's sadness caused the seasons. Alternatively, Deutsch points out, one could have just as easily explained the seasons as resulting from the god's happiness, which would make it a poor explanation because it is so easy to arbitrarily change details.
[David Deutsch, "A new way of explaining explanation"]
/ref> Without Deutsch's criterion, the 'Greek gods explanation' could have just kept adding justifications. The same criterion, of being "hard to vary", may be what makes the modern explanation for the seasons
A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's tilted orbit around the Sun. In temperate and po ...
a good one. None of the details about the earth rotating around the sun at a certain angle in a certain orbit can be easily modified without changing the theory's coherence.[
]
Relation to other criteria
The philosopher Karl Popper acknowledged it is logically possible to avoid falsification of a hypothesis by changing details to avoid any criticism, adopting the term an '' immunizing stratagem'' from Hans Albert
Hans Albert (born 8 February 1921) is a German philosopher. Born in Cologne, he lives in Heidelberg.
His fields of research are Social Sciences and General Studies of Methods. He is a critical rationalist, paying special attention to rational ...
. Popper argued that scientific hypotheses should be subjected to methodological testing to select for the strongest hypothesis.[Karl R. Popper (1934), ''The Logic of Scientific Discovery'', p.20, Routledge Classics (ed. 2004)]
See also
* Falsifiability
Falsifiability is a standard of evaluation of scientific theories and hypotheses that was introduced by the philosopher of science Karl Popper in his book '' The Logic of Scientific Discovery'' (1934). He proposed it as the cornerstone of a s ...
* Razor (philosophy)
In philosophy, a razor is a principle or rule of thumb that allows one to eliminate ("shave off") unlikely explanations for a phenomenon, or avoid unnecessary actions.
Razors include:
*Occam's razor: Simpler explanations are more likely to be corr ...
* Critical Rationalism
References
Philosophy of science
Metatheory
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