Deduction may refer to:

Philosophy

Deductive reasoning Deductive reasoning is the mental process of drawing deductive inferences. An inference is deductively valid if its conclusion follows logically from its premises, i.e. if it is impossible for the premises to be true and the conclusion to be false ...

, the mental process of drawing inferences in which the truth of their premises ensures the truth of their conclusion *

Natural deduction In logic and proof theory, natural deduction is a kind of proof calculus in which logical reasoning is expressed by inference rules closely related to the "natural" way of reasoning. This contrasts with Hilbert-style systems, which instead use a ...

, a class of proof systems based on simple and self-evident rules of inference that aim to closely mirror how reasoning actually occurs

Taxation

Tax deduction Tax deduction is a reduction of income that is able to be taxed and is commonly a result of expenses, particularly those incurred to produce additional income. Tax deductions are a form of tax incentives, along with exemptions and tax credits. ...

, variable tax dollars subtracted from gross income **

Itemized deduction Under United States tax law, itemized deductions are eligible expenses that individual taxpayers can claim on federal income tax returns and which decrease their taxable income, and is claimable in place of a standard deduction, if available. Mo ...

, eligible expense that individual taxpayers in the United States can report on their Federal income tax returns **

Standard deduction Under United States tax law, the standard deduction is a dollar amount that non- itemizers may subtract from their income before income tax (but not other kinds of tax, such as payroll tax) is applied. Taxpayers may choose either itemized deduc ...

, dollar amount that non-itemizers may subtract from their income

Other uses

* English modals of deduction, English modal verbs to state how sure somebody is about something. * Deduction (food stamps), used in the United States to calculate a household's monthly food stamp benefit goods

Philosophy

Taxation

Other uses

See also