AskDefine | Define deductive

Dictionary Definition

deductive adj
1 relating to logical deduction; "deductive reasoning"
2 involving inferences from general principles [ant: inductive]

User Contributed Dictionary

English

Adjective

  1. Of, pertaining to, or based on deduction.
  2. Based on inferences from general principles.

Translations

  • Greek: παραγωγικός (paragogikós) (logic)
  • Italian: deduttivo

Derived terms

Extensive Definition

Deductive reasoning is reasoning which uses deductive arguments to move from given statements (premises), which are assumed to be true, to conclusions, which must be true if the premises are true.
The classic example of deductive reasoning, given by Aristotle, is
  • All men are mortal. (major premise)
  • Socrates is a man. (minor premise)
  • Socrates is mortal. (conclusion)
For a detailed treatment of deduction as it is understood in philosophy, see Logic. For a technical treatment of deduction as it is understood in mathematics, see mathematical logic.
Deductive reasoning is often contrasted with inductive reasoning, which reasons from a large number of particular examples to a general rule.

Background

Deductive reasoning was developed by Aristotle, Thales, Pythagoras, and other Greek philosophers of the Classical Period (600 to 300 B.C.). Aristotle, for example, relates a story of how Thales used his skills to deduce that the next season's olive crop would be a very large one. He therefore bought all the olive presses and made a fortune when the bumper olive crop did indeed arrive.
Deductive reasoning is dependent on its premises. That is, a false premise can possibly lead to a false result, and inconclusive premises will also yield an inconclusive conclusion.
Alternative to deductive reasoning is inductive reasoning. The basic difference between the two can be summarized in the deductive dynamic of logically progressing from general evidence to a particular truth or conclusion; whereas with induction the logical dynamic is precisely the reverse. Inductive reasoning starts with a particular observation that is believed to be a demonstrative model for a truth or principle that is assumed to apply generally.
Deductive reasoning applies general principles to reach specific conclusions, whereas inductive reasoning examines specific information, perhaps many pieces of specific information, to impute a general principle. By thinking about phenomena such as how apples fall and how the planets move, Isaac Newton induced his theory of gravity. In the 19th century, Adams and LeVerrier applied Newton's theory (general principle) to deduce the existence, mass, position, and orbit of Neptune (specific conclusions) from perturbations in the observed orbit of Uranus (specific data).

Deductive logic

Deductive reasoning is supported by deductive logic
For example:
All apples are fruit.
All fruits grow on trees.
Therefore all apples grow on trees.
Or
All apples are fruit.
Some apples are red.
Therefore some fruits are red.
The first premise may be false yet anyone accepting the premises is compelled to accept the conclusion.

Natural deduction

Deductive reasoning should be distinguished from the related concept of natural deduction, an approach to proof theory that attempts to provide a formal model of logical reasoning as it "naturally" occurs.

Cultural references

Sherlock Holmes, the fictional detective created by Sir Arthur Conan Doyle, is well known for referring to deductive reasoning in numerous of Doyle's stories.

Further reading

  • Vincent F. Hendricks, Thought 2 Talk: A Crash Course in Reflection and Expression, New York: Automatic Press / VIP, 2005, ISBN 87-991013-7-8
  • Zarefsky, David, Argumentation: The Study of Effective Reasoning Parts I and II, The Teaching Company 2002
portal Logic
deductive in Bosnian: Dedukcija
deductive in Bulgarian: Дедукция
deductive in Czech: Dedukce
deductive in Danish: Deduktion
deductive in German: Deduktion
deductive in Estonian: Deduktsioon
deductive in Spanish: Razonamiento deductivo
deductive in French: Déduction logique
deductive in Galician: Dedución
deductive in Korean: 연역법
deductive in Croatian: Dedukcija
deductive in Icelandic: Afleiðsla
deductive in Italian: Deduzione
deductive in Hebrew: דדוקציה
deductive in Latvian: Dedukcija
deductive in Hungarian: Dedukció
deductive in Macedonian: Дедукција
deductive in Dutch: Deductie
deductive in Japanese: 演繹
deductive in Norwegian: Deduksjon (filosofi)
deductive in Norwegian Nynorsk: Deduksjon
deductive in Uzbek: Deduksiya
deductive in Polish: Rozumowanie dedukcyjne
deductive in Portuguese: Método dedutivo
deductive in Romanian: Raţionament deductiv
deductive in Russian: Дедуктивное умозаключение
deductive in Slovenian: Dedukcija
deductive in Serbian: Дедукција
deductive in Serbo-Croatian: Dedukcija
deductive in Finnish: Deduktiivinen päättely
deductive in Swedish: Deduktion
deductive in Vietnamese: Suy diễn logic
deductive in Turkish: Tümdengelim
deductive in Ukrainian: Дедукція
deductive in Chinese: 演绎推理

Synonyms, Antonyms and Related Words

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