Burden of proof (logical fallacy)

In philosophy, the term burden of proof refers to the extent to which, or the level of rigour with which, it is necessary to establish, demonstrate or prove something for it to be accepted as true or reasonable to believe.

All logical arguments depend on certain premises being accepted for their conclusions to follow, and most logical arguments require a certain level of informality to be stated in a compact and comprehensible form. [Even the hyper-rigorous Nicolas Bourbaki points out that "in practice, the mathematician who wishes to satisfy himself of the [correctness] of a proof or theory hardly ever has recourse to one or another of the complete formalisations .. nor even usually to the incomplete and partial formalisations" "Theory of Sets" Addison-Wesley (1968) p8] Therefore it is always possible to seek to discredit an idea by suggesting that the Burden of Proof should be set to an inappropriately high level. For example when behaviourism was the dominant ideology in the study of animal behaviour, but social conditioning was dominant in human behaviour according to Mary Midgley.

there was a remarkable discrepancy between what was treated as a parsimonious explanation for a piece of human behaviour and what could count as such when the behaviour was of some other animal. The practice was that, in the human case, the normal, indeed practically the only, licensed form of explanation was in terms of culture or of free deliberate choice, or both. Anyone who suggested that an inborn tendency might be even a contributing factor in human choices tended to be denounced as a fascist. The burden of proof was accordingly laid entirely on this suggestion, and it was made impossibly heavy. To put it another way, any explanation that invoked culture, however vague, abstract, far-fetched, infertile and implausible, tended to be readily accepted, while any explanation in terms of innate tendencies, however careful, rigorous, well-documented, limited and specific tended to be ignored. In animal psychology, however, the opposite situation reigned. Here, what was taboo was the range of concepts that describes the conscious, cognitive side of experience. The preferred, safe kind of explanation here derived from ideas of innate programming and mechanical conditioning. If anything cognitive was mentioned, standards of rigour at once soared into a stratosphere where few arguments could hope to follow. [Mary Midgley "The Myths We Live By" Routelege (2004) ISBN 0415340772 p142-3. Emphasis added.]

The logical fallacy which she is exposing in this case is the attempt to argue that view A is to be preferred to view B because "B cannot be proven" when the burden of proof is laid on view B to an impossibly heavy level, and in particular to a level under which A could not be proven either.

Keith Lehrer suggests that "generally arguments about where the burden of proof lies are unproductive. It is more reasonable to suppose that such questions are best left to courts of law where they have suitable application. In "philosophy" a different principle of agnoiology [the study of ignorance] is appropriate, to wit, that no hypothesis should be rejected as unjustified without argument against it. Consequently, if the sceptic puts forth a hypothesis inconsistent with the hypothesis of common sense, then there is no burden of proof on either side …" [ Keith Lehrer 1971, "Why Not Skepticism?" The Philosophical Forum, 2/3, 283-298. p53 (Page reference is to the reprint in The Theory of Knowledge, L. Pojman (ed.), Belmont, CA: Wadsworth Publishing Company, 1993.) - quoted in [http://plato.stanford.edu/entries/skepticism/ Stanford Encyclopedia of Philosophy] )]

ee also

* Negative proof
* Thomas Reid

Notes and References