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deduction

deduction, in logic, form of inference such that the conclusion must be true if the premises are true. For example, if we know that all men have two legs and that John is a man, it is then logical to deduce that John has two legs. Logicians contrast deduction with induction, in which the conclusion might be false even when the premises are true. Deduction has to do with necessity; induction has to do with probability. The famous Aristotelian syllogism is one species of deductive reasoning, which was greatly extended by the development of symbolic logic.

See R. J. Ackermann, Modern Deductive Logic (1971); P. J. Hurley A Concise Introduction to Logic (1985).

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deduction

de·duc·tion / diˈdəkshən/ • n. 1. the action of deducting or subtracting something: the dividend will be paid without deduction of tax. ∎  an amount that is or may be deducted from something, esp. from taxable income or tax to be paid: tax deductions. 2. the inference of particular instances by reference to a general law or principle: the detective must uncover the murderer by deduction from facts. Often contrasted with induction. ∎  a conclusion that has been deduced.

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deduction

deduction, deductive The use of logical rules to arrive at a set of premisses from which certain conclusions must follow. Deduction begins with theory, moves to hypotheses derived from the theory, and then tests hypotheses via prediction and observations. This approach to testing and theory is often referred to as the hypothetico-deductive method, and since it emphasizes hypotheses, prediction, and testing, is sometimes held to be the method par excellence of science. See also INDUCTION.

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Deduction

DEDUCTION

That which is deducted; the part taken away; abatement; as in deductions from gross income in arriving at net income for tax purposes.

Incivil law, a portion or thing that an heir has a right to take from the mass of the succession before any partition takes place.

A contribution to a charity can be used as a deduction to reduce income for income tax purposes if the taxpayer meets the requirements imposed by law.

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deduction

deduction A formal method of logical inference. Deduction is the process of applying one or more inference rules to a given set of facts (known as axioms) and inferring new facts. Unlike the other methods of inference, abduction and induction, deduction produces logically sound results, i.e. involves no uncertainty.

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deduction

deductionashen, fashion, passion, ration •abstraction, action, attraction, benefaction, compaction, contraction, counteraction, diffraction, enaction, exaction, extraction, faction, fraction, interaction, liquefaction, malefaction, petrifaction, proaction, protraction, putrefaction, redaction, retroaction, satisfaction, stupefaction, subtraction, traction, transaction, tumefaction, vitrifaction •expansion, mansion, scansion, stanchion •sanction •caption, contraption •harshen, Martian •cession, discretion, freshen, session •abjection, affection, circumspection, collection, complexion, confection, connection, convection, correction, defection, deflection, dejection, detection, direction, ejection, election, erection, genuflection, imperfection, infection, inflection, injection, inspection, insurrection, interconnection, interjection, intersection, introspection, lection, misdirection, objection, perfection, predilection, projection, protection, refection, reflection, rejection, resurrection, retrospection, section, selection, subjection, transection, vivisection •exemption, pre-emption, redemption •abstention, apprehension, ascension, attention, circumvention, comprehension, condescension, contention, contravention, convention, declension, detention, dimension, dissension, extension, gentian, hypertension, hypotension, intention, intervention, invention, mention, misapprehension, obtention, pension, prehension, prevention, recension, retention, subvention, supervention, suspension, tension •conception, contraception, deception, exception, inception, interception, misconception, perception, reception •Übermenschen • subsection •ablation, aeration, agnation, Alsatian, Amerasian, Asian, aviation, cetacean, citation, conation, creation, Croatian, crustacean, curation, Dalmatian, delation, dilation, donation, duration, elation, fixation, Galatian, gyration, Haitian, halation, Horatian, ideation, illation, lavation, legation, libation, location, lunation, mutation, natation, nation, negation, notation, nutation, oblation, oration, ovation, potation, relation, rogation, rotation, Sarmatian, sedation, Serbo-Croatian, station, taxation, Thracian, vacation, vexation, vocation, zonation •accretion, Capetian, completion, concretion, deletion, depletion, Diocletian, excretion, Grecian, Helvetian, repletion, Rhodesian, secretion, suppletion, Tahitian, venetian •academician, addition, aesthetician (US esthetician), ambition, audition, beautician, clinician, coition, cosmetician, diagnostician, dialectician, dietitian, Domitian, edition, electrician, emission, fission, fruition, Hermitian, ignition, linguistician, logician, magician, mathematician, Mauritian, mechanician, metaphysician, mission, monition, mortician, munition, musician, obstetrician, omission, optician, paediatrician (US pediatrician), patrician, petition, Phoenician, physician, politician, position, rhetorician, sedition, statistician, suspicion, tactician, technician, theoretician, Titian, tuition, volition •addiction, affliction, benediction, constriction, conviction, crucifixion, depiction, dereliction, diction, eviction, fiction, friction, infliction, interdiction, jurisdiction, malediction, restriction, transfixion, valediction •distinction, extinction, intinction •ascription, circumscription, conscription, decryption, description, Egyptian, encryption, inscription, misdescription, prescription, subscription, superscription, transcription •proscription •concoction, decoction •adoption, option •abortion, apportion, caution, contortion, distortion, extortion, portion, proportion, retortion, torsion •auction •absorption, sorption •commotion, devotion, emotion, groschen, Laotian, locomotion, lotion, motion, notion, Nova Scotian, ocean, potion, promotion •ablution, absolution, allocution, attribution, circumlocution, circumvolution, Confucian, constitution, contribution, convolution, counter-revolution, destitution, dilution, diminution, distribution, electrocution, elocution, evolution, execution, institution, interlocution, irresolution, Lilliputian, locution, perlocution, persecution, pollution, prosecution, prostitution, restitution, retribution, Rosicrucian, solution, substitution, volution •cushion • resumption • München •pincushion •Belorussian, Prussian, Russian •abduction, conduction, construction, deduction, destruction, eduction, effluxion, induction, instruction, introduction, misconstruction, obstruction, production, reduction, ruction, seduction, suction, underproduction •avulsion, compulsion, convulsion, emulsion, expulsion, impulsion, propulsion, repulsion, revulsion •assumption, consumption, gumption, presumption •luncheon, scuncheon, truncheon •compunction, conjunction, dysfunction, expunction, function, junction, malfunction, multifunction, unction •abruption, corruption, disruption, eruption, interruption •T-junction • liposuction •animadversion, aspersion, assertion, aversion, Cistercian, coercion, conversion, desertion, disconcertion, dispersion, diversion, emersion, excursion, exertion, extroversion, immersion, incursion, insertion, interspersion, introversion, Persian, perversion, submersion, subversion, tertian, version •excerption

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Deduction

DEDUCTION

Deduction is a type of reasoning whereby a person concludes from one or more given premises to a proposition that is their necessary and logical consequent (see ar gumentation; syllogism). The term is of recent origin in the history of logic, its French equivalent appearing only in the last edition (1835) of the Dictionnaire de l'Académie française. aristotle characterizes a certain type of argument as παγωγή, which is rendered into Latin as deductio but is better translated into English as reduction; the argument known as reductio ad impossibile is of this type (Anal. pr. 29b 6; see also ibid. 69a 20). Again, thomas aquinas uses the term deductio in at least four different senses, none of which has the precise modern signification [see L. Schütz, ThomasLexikon (2d ed. Paderborn 1895; repr. Stuttgart 1958) 203]. I. kant speaks too of a transcendental deduction as part of his transcendental method. see transcendental (kant ian). Modern logicians sometimes oppose deduction to induction on the basis that the first concludes from the general to the particular, whereas the second concludes from the particular to the general; this characterization is inaccurate, however, since deduction need not conclude to the particular and its process is far from being the logical inverse of the inductive procedure (see induction; demonstration). For specific teachings on deduction, see R. eisler, Wörterbuch der philosophischen Begriffe, 3 v. (4th ed. Berlin 192730) 1:245247.

See Also: logic, symbolic.

[r. houde]

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