Logos Multilingual Portal

13 - Deduction and induction

"To conceal your embarrassment,
you stand up and lean out of the window,
still holding the volume in your hand"1.

In the previous units of this part of the course, devoted to the first phase of translation - reading - we have faced some of the psychological and psychoanalytical aspects of decoding and interpretation. In order to go on with our exam of the problems of reading, we must now partially withdraw from the psychological sphere and try to understand what happens at a logical level when we face a text, what are the reasoning we face to work out meanings out of the text.
  In order to do that, we will conspicuously draw on the science of the action of signs, semiotics. The word "semiotics" is derived from "semiosis", from the Greek semeiosis, "action of signs". The modern term was coined by the great thinker from the U.S. Peirce (1839-1914) and, although simultaneously another researcher, Swiss, Ferdinand de Saussure (1857-1914), was creating "semiology" - a term by which semiotics, or at least linguistic semiotics, is better known in Europe -, the two men had never heard of the existence of the other. This is, above all, caused by the fact that, even if with the benefit of hindsight he can be considered a fundamental element in the history of human thought, Peirce never found a permanent job in any American university, and earned his living sometimes by temporary jobs often beneath his standing, stealing time from his precious studies. That did not prevent him from leaving roughly a hundred thousand written pages, of which only a small part has been published so far.
  Let us examine the main kinds of logic characterizing any cognitive act with which we try to understand something. The simplest and the safest is deduction, an analytical reasoning, proceeding from the general to the particular. Let us look at Aristotle's example: starting from a major premise, a rule including many cases,

A "all men are mortal",

a minor one is pronounced - a rule meant as a subset to the major premise:

B "Socrates is a man".

The consequence derived from that, the conclusion, is that

C "Socrates is mortal".

This kind of logic has the characteristic of not being risky at all: if you are certain of the validity of A and B, you can be sure that C is true as well. The problem with deduction is, if anything, another one: although useful when applying general rules to individual cases, it is not at all creative because it does not add anything new to what is already known. Peirce illustrated deduction with the example, now famous, of the bean bag:

RuleAll the beans from this bag are white.
CaseThese beans are from this bag.
ResultThese beans are white2.

Wishing to try a more creative logic, one can observe what happens modifying the order of the elements in deduction. Induction is, in some respects, the opposite of deduction, because the premises from which it begins are the minor ones so that the logic proceeds from the particular to the general. It is a synthetic logic:

A "The pencil falls".

The observation of a specific case, undoubtedly true, a fact known to anyone who has ever dropped a pencil. In induction there are many other minor premises, for example:

B "The book falls",

very easily verifiable,

C "The man falls".

To arrive at the conclusion, however, and state the general rule 'on the basis of' these particular cases, a logical leap is necessary in order to state:

D "All bodies fall".

This logic, based on the empirical world and not solely on the laws of logics, because it starts from the practical observation of objective phenomena, is creative, because D is much more than the sum of A, B, and C. The minus side is that we do not have any certainty that D is true. So, if induction is useful logic for stating hypotheses on rules not yet clearly focused, on the other hand it is useful only to create hypotheses, not convictions as in the case of deduction.
  Peirce, in this case too, uses the bag of beans example:

CaseThese beans are from this bag.
ResultThese beans are white.
RuleAll the beans from this bag are white3.

When we read and must understand the meanings of a text, which of these logics do we draw on? To choose deduction, we need a text that comes complete with the general rules for understanding it, a highly unlikely occurrence. In order to choose induction, we would need a text stating, right from the beginning, a specific rule governing its function, but this doesn't happen either.
  Semiosis - signification - our understanding of the text - do not follow a deductive or inductive logic. Semiosis develops like scientific research, and is not satisfied only with an analytical logic (deduction) or a synthetic (induction): the former, in Peirce's opinion, "proves that something must be", the latter "shows that something actually is operative"4. The logic that in Peirce's opinion operates in the moment when we extract meaning from a text is abduction: "Abduction merely suggests that something may be"5. Returning to the bag of beans example, abduction works like this:

RuleAll the beans from this bag are white.
ResultThese beans are white.
CaseThese beans are from this bag6.

The hypothesis at the basis of the final part of the reasoning is a case, not a rule; to be precise it is the hypothesis of a case. That the beans are from that particular bag is a working hypothesis, one that must be repeatedly checked throughout the course of the research. In the following units we will see the repercussions of such logic on the semiotic act.


Bibliographical references

CALVINO I. If on a Winter's Night a Traveller, translated by William Weaver, London, Vintage, 1998, ISBN 0-7493-9923-6.

GORLÉE D. L. Semiotics and the Proble of Translation. With Special Reference to the Semiotics of Charles S. Peirce. Amsterdam, Rodopi, 1994. ISBN 90-5183-642-2.

PEIRCE C. S. Collected Papers of Charles Sanders Peirce, a c. di Charles Hartshorne, Paul Weiss e Arthur W. Burks, 8 vol., Cambridge (Massachusetts), Harvard University Press, 1931-1966.

1 Calvino 1998, p. 242.
2 Peirce, vol. 2, p. 623.
3 Peirce, vol. 2, p. 623.
4 Peirce, vol. 5, p. 171.
5 Peirce, vol. 5, p. 171.
6 Peirce, vol. 2, p. 623.