Defeasible reasoning (1987)
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| Venue: | Cognitive Science |
| Citations: | 175 - 5 self |
BibTeX
@ARTICLE{Pollock87defeasiblereasoning,
author = {John L. Pollock},
title = {Defeasible reasoning},
journal = {Cognitive Science},
year = {1987},
volume = {11},
pages = {481--518}
}
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Abstract
There was a long tradition in philosophy according to which good reasoning had to be deduc-tively valid. However, that tradition began to be questioned in the 1960’s, and is now thoroughly discredited. What caused its downfall was the recognition that many familiar kinds of reasoning are not deductively valid, but clearly confer justification on their conclusions. Here are some simple ex-amples: Perception Most of our knowledge of the world derives from some form of perception. But clearly, percep-tion is fallible. For instance, I may believe that the wall is grey on the basis of its looking grey to me. But it may actually be white, and it only looks grey because it is dimly illuminated. In this example, my evidence (the wall’s looking grey) makes it reasonable for me to conclude that the wall is grey, but further evidence could force me to retract that conclusion. 1 Such a conclusion is said to be justi-fied defeasibly, and the considerations that would make it unjustified are defeaters. Induction There is one kind of reasoning that few ever supposed to be deductive, but it was often conven-iently ignored when claiming that good reasoning had to be deductive. This is inductive reasoning,
