Dear All,
Several times in the past few days, colleagues have written to ask for material on abduction, induction, and deduction — and the differences among them. Because this issue comes up frequently in research seminars and doctoral courses, I have gathered my notes from different replies to share them with the list.
There is a great deal of confusion on the issue of abduction. Put simply, it is a way to describe hypothesis formation. We often hear people describe induction as “inference to best explanation,” but this is not entirely accurate. While inductive inference is an inference to a *likely* best explanation, an inductive inference does not tell you whether the explanation is true, valid or correct.
Many of the false convictions that are now being overturned through DNA and other forms of scientific evidence were originally obtained by police officers or prosecutors who relied on abduction inference rather than hard evidence. One reads many versions of this story:
A crime takes place. Person X — or someone who looks like Person X — is seen in the area around the time of the crime. Despite the absence of hard evidence, if there are no other suspects for the crime, the *likely* best explanation is that Person X committed the crime. It is true that a crime has been committed. And it is therefore true that someone must be guilty. The problem with many convictions is that closing the case requires ascribing guilt.
Abduction also plays a role in many of the great tragedies of history. When much of the world believed in witches and witchcraft, people were killed as witches through accusations based on abduction. Now that we no longer believe in witchcraft, we recognise the accusations of witchcraft as false. Those accusations were often based on abductive inference.
Abduction is good when used properly.
Abduction had a role in many scientific breakthroughs and technological developments.
Scientists test abductive inferences. Inventions work — or they don’t.
It is incorrect to say that designers somehow achieve results through abduction while scientists use induction and deduction. Designers more often fail through abduction than they succeed. And scientists more often find that hypotheses fail than succeed. The point is to find what works, then find out why it works, without mistaking intuition or inspiration for valid conclusions.
The short version of the argument is that scientists and scholars use induction and deduction to achieve reliable scientific or scholarly results, where designers use abduction to achieve reliable outcomes. This is not so. Abduction is not a logic of justification, and reliability lies within the logic of justification.
It is also wrong to suggest that scientists and scholars do not use abduction. They do. Everyone uses abduction to some degree — in daily life as well as in research. Abduction involves hypothesis formation, but an hypothesis is only an idea without evidence to determine whether the idea has substance. Abductive inference it not reliable. It is indicative. Just as one must test hypotheses, one must test abduction to determine whether an abductive inference is correct.
Mautner’s Dictionary of Philosophy (2000: 1) explains abduction well:
“abduction n. 1 (in Aristotle) a syllogistic inference from a major premiss which is certain, and a merely probable minor premiss, to a merely probable conclusion (Prior Analytics 2,25 69a 2o ff.).
“2 (in C. S. Peirce) reasoning of this form: (a) facts of type B have been observed; (b) a true statement of the form If A then B can explain B. Therefore, probably A. Peirce called this pattern abduction, believing that he used the term in the Aristotelian sense. He held that abduction is the standard form of setting up scientific hypotheses, and can count as the third kind of inference, together with induction and deduction.Since then, it has been stressed that what makes A probable is that it is the best explanation we can think of. Scientifically useful abduction is, then, INFERENCE TO THE BEST EXPLANATION. The general form of such an inferenceis: (1) D is a collection of data; (2) H (a hypothesis) would, if true, explain D ; (3) no other hypothesis can explain D as well as H does (4) Therefore, H is probably true. Of course, abductive reasoning is common also in everyday life, whenever we try to find answers to questions why something is the case. Syn. retroduction.”
In design, many people refer to the great logician and scientists C. S. Peirce without actually reading Peirce. For Peirce, abduction belongs within the logic of discovery. One requires more than abduction for the logic of justification.
To see what Peirce (1998) has to say, I suggest the excellent collection from Indiana University Press.
Igor Douven (2011) wrote an excellent article on abduction in the Stanford Encyclopaedia of Philosophy.
http://plato.stanford.edu/entries/abduction/#DedIndAbd <http://plato.stanford.edu/entries/abduction/#DedIndAbd>
He also wrote a supplementary article on C. S. Peirce’s views
http://plato.stanford.edu/entries/abduction/peirce.html <http://plato.stanford.edu/entries/abduction/peirce.html>
Robin Smith’s (2015) discussion on induction and deduction appear in the article on Aristotle’s logic
http://plato.stanford.edu/entries/aristotle-logic/#IndDed <http://plato.stanford.edu/entries/aristotle-logic/#IndDed>
The Internet Encyclopaedia of Philosophy also has a good article on induction and deduction
http://www.iep.utm.edu/ded-ind/ <http://www.iep.utm.edu/ded-ind/>
Mautner (2000: 145) describes deduction this way:
“deduction n. The premisses in a deduction do not have to be general or necessary. But in that respect, older concepts of deduction differed: 1 a deduction is a valid inference from necessary premisses. This is a traditional concept of deduction. Descartes defined it as an operation by which we have insight into something which follows necessarily from other things that are known with certainty “Rule III in Regles pour la direction de l'esprit (Rules for the direction of the mind)”. 2 a deduction is a valid inference from more general premisses to a less general i.e. a more specific conclusion. It is contrasted with induction which is an inference from particular instances to a general conclusion. This is the classical Aristotelian concept. 3. (in older jurisprudence) a deduction establishes the legal in contradistinction to the factual grounds for action in a court of law. This is the sense used metaphorically by Kant in the Critique of Pure Reason. His ‘transcendental deduction’ of the categories is the justification of the application of the categories to objects, i.e. the account of why the categories necessarily apply to all objects of experience. 4 in the modern sense, a valid deduction or a valid deductive inference is one in which the conclusion is a necessary consequence of the premisses so that the conclusion cannot be false if all the premisses arc true. In contrast the conclusion of a sound INDUCTION is supported by the premisses and may be very probable given the premisses, but it can be false even if all the premisses are true.”
Here is Mautner's (2000: 273) discussion of induction:
“induction n. inference from a finite number of particular cases to a further case or to a general conclusion. For instance if a number of ravens have been observed all of which are black and if no raven has been encountered that is not black the inferences to the conclusion that the next observed raven will be black or to the general conclusion that all ravens are black are inductive inferences. Many inductive inferences seem plausible some indeed seem extremely plausible but the truth of all the premisses can never guarantee the truth of the conclusion since the conclusion goes beyond what is given in the premisses. In this respect they are contrasted with deductive inferences in which the truth of all the premisses guarantees the truth of the conclusion. Aristotle introduced the concept of induction in the Posterior Analytics. It has been claimed, however, that there ‘induction’ does not mean a process of reasoning but the examination of instances that results in a common feature coming to view.”
To summarise, valid deductive conclusions drawn from correct premisses lead to correct conclusions. It is nevertheless possible to have *logically valid* but *incorrect* conclusions. Lewis Carroll’s playful logic games offer delightfully silly examples of logically correct statements that are nevertheless false of silly.
One may reach inductive conclusions, but there is no way to render induction universally reliable in the same way that deduction is universally reliable.
Abduction is useful, but an abductive inference may useful without being correct. One valid use of abduction is that it may be a step in ruling conclusions out rather than in reaching them.
Designers who solve problems do best when they use multiple methods to reach conclusions, and they reach conclusions best when they test and examine both premisses and outcomes.
Yours,
Ken Friedman
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References
Douven, Igor. 2011. “Abduction." The Stanford Encyclopedia of Philosophy (Spring 2011 Edition). Edward N. Zalta, ed. URL http://plato.stanford.edu/archives/spr2011/entries/abduction/ <http://plato.stanford.edu/archives/spr2011/entries/abduction/>
Mautner, Thomas. 2000. The Penguin Dictionary of Philosophy. London: Penguin Books.
Peirce, C. S. 1998. The Essential Peirce. Selected Philosophical Writings. Volume 2. 1893-1913. Edited by the Peirce Edition Project. Bloomington, Indiana: Indiana University Press.
Smith, Robin. 2015. "Aristotle's Logic." The Stanford Encyclopedia of Philosophy (Summer 2015 Edition). Edward N. Zalta, ed. URL http://plato.stanford.edu/archives/sum2015/entries/aristotle-logic/ <http://plato.stanford.edu/archives/sum2015/entries/aristotle-logic/>
—
Ken Friedman, PhD, DSc (hc), FDRS | Editor-in-Chief | 设计 She Ji. The Journal of Design, Economics, and Innovation | Published by Tongji University in Cooperation with Elsevier | URL: http://www.journals.elsevier.com/she-ji-the-journal-of-design-economics-and-innovation/
Chair Professor of Design Innovation Studies | College of Design and Innovation | Tongji University | Shanghai, China ||| University Distinguished Professor | Centre for Design Innovation | Swinburne University of Technology | Melbourne, Australia
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