| Suppose that on a public holiday you are standing in the street in a town that has two bakeries. When you meet me, eating a loaf of bread, you draw the conclusion that at least one of the two bakeries is open. Further, seeing from a distance that one of the two bakeries has its lights on, you believe that this particular bakery is open. When you reach this conclusion, you are doing abduction. Of course, there may be other possibilities, say, the lights are turned on only for the purpose of cleaning and the bakery is closed. However, you are unlikely to draw such a conclusion because it is not the best explanation in the given situation. The process via which we try to arrive at the best explanation is abduction. In fact, abduction is very important not only in our everyday lives, but in scientific discovery. In medical diagnosis, it is also very important. The method used by detectives in detective stories is also characteristic of abduction.Abduction is first clearly suggested by Peirce, whose abductive theories have undergone great changes from a reasoning mode to a stage in scientific inquires. In his early writing "Deduction, Induction and Hypothesis" (1878), Peirce describes the three modes of inference as different syllogistic forms in the context of Aristotle's syllogistic. Abduction is reserved for the method of reasoning that leads to truly new findings. It is a method, which, for example, licenses the move from an observation such as "the white beans are on the table," to the fresh inference "these beans come from this bag." This "discovery" is made possible by the introduction of a rule that establishes that an inference such as "the beans in this bag are white" is a plausible and possibly correct abduction.In Peirce's "Lectures on Pragmatism" (1903) abduction, deduction and induction become interacting aspects with different epistemological functions. According to Peirce, abduction constitutes the "first stage" of scientific inquiries (CP6.469) and of any interpretive processes. Abduction is the process of adopting an explanatory hypothesis (CP 5.145) and covers two operations: the selection and the formation of plausible hypotheses. As a process of finding premises, it is the basis of interpretive reconstruction of causes and intentions, as well as of inventive construction of theories. Deduction determines the necessary consequences, relying on logical provable coherence between premises and conclusion. Induction is aiming at empirical provable coherence between the premises and experience, in order to derive a probable generalization. Yet, induction only classifies the data (CP 3.516), while abductive reasoning furnishes the reasoner with a problematic theory explaining the causal relation among the facts. From the abductive suggestion, which syntheses a multitude of predicates, "deduction can draw a prediction which can be tested by induction" (CP 5.171). Thinking and reasoning is based on abductive, deductive and inductive inferences, aiming at establishing beliefs, habits, rules and codes.Motivated by the observation of a surprising fact or an anomaly that disappoints an expectation, abductive reasoning is a strategy of solving problems and discovering relevant premises. It is "inference to the best explanation". Abductive reasoning has the logical form of an inverse modus ponens and is "reasoning backwards" from consequent to antecedent. Therefore Peirce calls it also "Retroductive reasoning" (CP 1.74). From a logical point of view, reasoning backwards is no valid form of inference. It is conjectural, or presumptive thinking, aiming at matching pragmatic standards of plausibility, guided by the reasoner's "guessing instinct" (CP 7.46). However, Peirce claims that abduction is logical inference, because it can be represented in a "a perfect definite logical form" (CP 5.188): "The surprising fact, C, is observed; But if A were true, C would be a matter of course, Hence, there is reason to suspect that A is true" (CP 5.189). Hanson (1965: 45) differentiates between two aspec... |
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