Ad hoc hypothesis

An ad hoc hypothesis is an auxiliary hypothesis that is set up ad hoc , i.e. for an individual case, in order to counter observations or critical arguments that could falsify the attacked theory . The term goes back to the Austro-British scientific theorist Karl Popper .

Popper

Karl Popper introduced the term in his 1934 manuscript The Two Basic Problems of Epistemology , a preliminary version of the logic of research . Ad-hoc hypotheses are therefore singular auxiliary assumptions about a certain space-time point, which only served to immunize the hypothesis to be defended against certain falsifications , and therefore do not become an integral part of the theoretical system in which the hypothesis stands. In this respect, Popper understands ad-hoc hypotheses as methodologically reprehensible, as a trick to "want to save a favorite theory", as he expressed in 1960:

"Some genuinely testable theories, when found to be false, are still upheld by their admirers - for example by introducing ad hoc some auxiliary assumption, or by re-interpreting the theory ad hoc in such a way that it escapes refutation. Such a procedure is always possible, but it rescues the theory from refutation only at the price of destroying, or at least lowering, its scientific status. (I later described such a rescuing operation as a 'conventionalist twist' or a 'conventionalist stratagem'.) "

Scientific practice

Hardly any scientist can do without ad hoc hypotheses. In 1975, the Austrian theorist of science Paul Feyerabend , in his standard work Wider den Methodenzwang, extensively dealt with ad hoc hypotheses which, in his opinion, “give new theories a breathing space and they indicate the direction of future research”.

Statistical outliers that do not match the rest of the data in the data set are usually interpreted ad hoc as coincidences or measurement errors, as part of the noise from which the significant signals have to be isolated. Nonetheless, according to Ockham's razor, it is considered good scientific practice to consider the result as valid that gets along with the fewest ad hoc hypotheses. Repeated use of ad hoc hypotheses is a hallmark of pseudoscience .

Scientific examples

Max Planck established the ad hoc assumption that the physical effect only in multiples of a quantum of action can occur, the quantum physics .

In his formulation of the atomic model presented Niels Bohr , the postulate on that the electrons in the radial acceleration on their orbits no bremsstrahlung post.

The continuous spectrum of beta decay was explained by Wolfgang Pauli through the ad-hoc hypothesis of the existence of a massless elementary particle , the neutrino , that was previously unobserved .
The Fitzgerald-Lorentz contraction hypothesis , explaining the Michelson-Morley experiment
Einstein's cosmological constant , which should prevent an expansion or contraction of the universe resulting from his theory .

Individual evidence

^ Gunnar Andersson: Critique and History of Science. Kuhn's, Lakatos' and Feyerabend's Critique of Critical Rationalism. JCB Mohr, Tübingen 1988, p. 143.

↑ Karl Popper: Conjectures and Refutations: The Growth of Scientific Knowledge , 2nd ed. 1965, pages 8- 9 pdf ( Memento of the original from September 9, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2
^ John McAdams: JFK Assassination Logic. How to think about claims of conspiracy. Potomac Books, Lincoln 2011, p. 12 and ö.
^ Scott Lilienfeld: Pseudoscience in contemporary clinical psychology. What it is, and what we can do about it. In: Bryan Farha: Pseudoscience and Deception. The Smoke and Mirrors of Paranormal Claims. University Presse of America, Lanham MD 2014, p. 134 f.

literature

Karl Popper : Logic of Research . 11th edition. Mohr Siebeck, Tübingen 2005, ISBN 3-16-146234-3 .
Paul Feyerabend : Against Method. Outline of an Anarchistic Theory of Knowledge . Mohr Siebeck, Frankfurt 1975, ISBN 3-518-28197-6 .

[1] Gunnar Andersson: Critique and History of Science. Kuhn's, Lakatos' and Feyerabend's Critique of Critical Rationalism. JCB Mohr, Tübingen 1988, p. 143.