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Encyclopedia > Deductive reasoning

Deductive reasoning is reasoning whose conclusions are intended to necessarily follow from its premises. It is more commonly understood as the type of reasoning that proceeds from general principles or premises to derive particulars[1], although this is a less precise understanding. Deductive reasoning "merely" reveals the implications of propositions, laws, or general principles, so that, like some philosophers claim, it does not add to truth. Reasoning is the mental (cognitive) process of looking for reasons to support beliefs, conclusions, actions or feelings. ... A conclusion is a final proposition, which is arrived at after the consideration of evidence, arguments or premises. ... Look up Premise in Wiktionary, the free dictionary. ... The material conditional, also known as the material implication or truth functional conditional, expresses a property of certain conditionals in logic. ... This article is about the word proposition as it is used in logic, philosophy, and linguistics. ...

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.[2] For other uses, see Aristotle (disambiguation). ... For the Defense and Security Company, see Thales Group. ... Pythagoras of Samos (Greek: ; born between 580 and 572 BC, died between 500 and 490 BC) was an Ionian Greek mathematician[1] and founder of the religious movement called Pythagoreanism. ...

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.[3]

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. Aristotle appears first to establish the mental behaviour of induction as a category of reasoning. ...

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). Sir Isaac Newton FRS (4 January 1643 â€“ 31 March 1727) [ OS: 25 December 1642 â€“ 20 March 1727][1] was an English physicist, mathematician, astronomer, natural philosopher, and alchemist. ... Isaac Newtons theory of universal gravitation (part of classical mechanics) states the following: Every single point mass attracts every other point mass by a force pointing along the line combining the two. ... Alternative meaning: Nineteenth Century (periodical) (18th century — 19th century — 20th century — more centuries) As a means of recording the passage of time, the 19th century was that century which lasted from 1801-1900 in the sense of the Gregorian calendar. ... Neptune The discovery of the planet Neptune on September 23, 1846 was a dramatic incident in the history of astronomy that also led to a tense international dispute over priority. ... For other uses, see Mass (disambiguation). ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... For other uses, see Neptune (disambiguation). ... For other uses, see Uranus (disambiguation). ...

Deductive logic

Deductive reasoning is supported by deductive logic (which is not quite the same thing).

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.

Intuitively, one might deny the major premise and hence the conclusion; yet anyone accepting the premises accepts the conclusion.

Natural deduction

Main article: 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. In mathematical logic, natural deduction is an approach to proof theory that attempts to provide a formal model of logical reasoning as it naturally occurs. ... In mathematical logic, natural deduction is 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. This article is about Arthur Conan Doyles fictional detective. ... A fictional character is any person, persona, identity, or entity whose existence originates from a work of fiction. ... Gumshoe redirects here. ... Arthur Conan Doyle Sir Arthur Ignatius Conan Doyle (May 22, 1859 - July 7, 1930) is the British author most famously known for his stories about the detective Sherlock Holmes, which are generally considered a major innovation in the field of crime fiction. ...

• 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

Vincent F. Hendricks is a philosopher and logician. ...

References

 Logic Portal
Look up Deductive reasoning in
Wiktionary, the free dictionary.

Results from FactBites:

 Anxiety Zone - Deductive reasoning (342 words) Deductive reasoning is the process of reaching a conclusion that is guaranteed to follow, if the evidence provided is true and the reasoning used to reach the conclusion is correct. Deductive reasoning was first described by the ancient Greek philosophers such as Aristotle. Deductive reasoning is fundamentally in the form of an assertion of idea to materialisation, while inductive reasoning is from empirical evidence to formulate the generalise knowledge of the observation thereof.
More results at FactBites »

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