Charles sanders peirce

Charles Sanders PeirceandPierce’s Deductive Logicon Stanford Encyclopedia of Philosophy

Peirce believed that there was something worth investigating in terms of logic analysis in the matter of the discovery of hypotheses.

The logic of Abduction

A different type of logic we needed to adopt: abductive, anampliativetype of inference


analytic and deductiveabductive and inductive

Although it [abduction] is very little hampered by logical rules, nevertheless it is logical inference, asserting its conclusion only problematically or conjecturally, it is true, but nevertheless having a perfectly defined logical form


Reasoning abductively

Deduction proves that something must be;
Induction shows that something actually is operative;
Abduction merely suggests that something may be.


every inquiry whatsoever takes its rise in the observation […] of some surprising phenomenon. The inquiry begins with pondering these phenomena in all their aspects, in the search of some point of view whence the wonder shall be resolved. At length a conjecture arises that fournishes a possible explanation, by which I mean a syllogism exhibiting the surprising fact as necessarily consequent upon the circumstances of its occurrence together with the truth of the credible conjecture, as premises.


An inference not to the final truth of the hypotheses, but to the plausibility for my hypotheses to be true.
The best way to do this, if of course sending the hypotheses of to trial.

think of what trillions and trillions of hypotheses might be made of which only one is true; and yet after two or three or at the very best a dozen guesses, a physicist hits pretty nearly on the correct hypothesis. By chance he would not have been likely to do so in the whole time has elapsed since the earth was solidified.


Three absolutely separate types of inference.

Types of inference

all part of the same process of inquiry:

  • abduction consists of inventing or proposing a hypotheses
  • deduction deduction consists in inferring the consequences of an H to be tested
  • induction consists in completing the testing

Making a hypothetical assertion

  1. the hypothesis must explain the facts
  2. the hypothesis must add knowledge to the facts
  3. the hypothesis creates resemblance between different types of facts
  4. the hypothesis must allow to acquire a new truth

Continues in:Testing the hypotheses



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