Deductive and Inductive Reasoning

DEDUCTIVE AND INDUCTIVE REASONING

by Antonio C. Antonio

February 17, 2015

Reasoning is the action and process of thinking about something in a logical, deliberate and sensible way.  There are two general types of reasoning… deductive and inductive.

Deductive Reasoning is a logical process by which a conclusion is based on the concordance (meaning: an alphabetical list of words, especially the important ones, present in a text, usually with the necessary citations of the passages concerned) of multiple premises that are generally assumed to be true.  On the other hand and as opposed to deductive reasoning, Inductive Reasoning is reasoning in which the premises (meaning: a statement or idea that is accepted as being true and that is used as the basis of an argument) seek to supply strong evidence for, although not an absolute proof of, the truth of the conclusion.

Deductive Reasoning is oftentimes referred to as “top-down” logic while its counterpart, Inductive Reasoning, is sometimes referred to as “bottom-up” logic.  While Deductive Reasoning starts from a general premise that leads to a specific conclusion, Inductive Reasoning starts from a specific premises and ends with a general conclusion.

Aristotle, a Greek philosopher, considered to be the father of Deductive Reasoning wrote the following classic example: “All men are mortal.  Socrates is a man. Therefore, Socrates is mortal.”  This example is also referred to as a syllogism (meaning: an instance of a form of reasoning in which a conclusion is drawn, whether valid or not, from two given or assumed propositions or premises each of which shares a term with the conclusion, and shares a common or middle term not present in the conclusion), the premises of the argument are self-evidently true.  In this example, because the premises establish that Socrates is an individual in a group whose members are all mortal, the inescapable conclusion is that Socrates must likewise be mortal.

Inductive Reasoning is largely defined as reasoning that derives general principles from specific observations.  The philosophical definition of Inductive Reasoning is more nuanced (meaning: a subtle difference in or shade of meaning, expression or sound) than simple progression from particular/individual instances to broader generalizations.  Rather, the premises of an inductive logical argument indicate some degree of support (also known as inductive probability) for the conclusion which only suggests truth but cannot guarantee the conclusion to be an absolute truth.  Inductive Reasoning is reasoning in which the premise seeks to provide strong evidence for the truth of the conclusion although this may not be an absolute proof.  In deductive reasoning, however, the conclusion is supposed to be certain as opposed to the conclusion being a mere probability with inductive reasoning.

A colloquial (meaning: assertions used in ordinary or familiar conversation but not formal or literary) example of Inductive Reasoning is: “Everything comes from something. Olive oil is made of olives.  Therefore, baby oil is made of babies.”  Compared to the classic example of deductive reasoning of Aristotle, my colloquial example seems crazy…  such is the peculiar parallelism between deductive and inductive reasoning.

Just my little thoughts…

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REFERENCES:

Alfaro-LeFevre, R. (2009). Critical thinking and clinical judgement: A practical approach to outcome-focused thinking. (4th ed.). St Louis: Elsevier.

Goldin-Meadow, S. (2005). Hearing gesture: How our hands help us think. Cambridge, MA: Harvard University Press.

Huttenlocher, J., Levine, S., & Vevea, J. (1998). Environmental input and cognitive growth: A study using time-period comparisons. Child Development, 69(4), 1012–1029.

Reed, S. K. (2010). Thinking visually. New York, NY: Psychology Press.