deduction

deduction 1 Deduction, abatement, rebate, discount are comparable when they mean an amount subtracted from a gross sum.

Deduction is interchangeable with any of the others but not without some loss in precision.

An abatement is a deduction from a levied tax or impost

{

an abatement of the duties levied at the customhouse

}

A rebate is an amount deducted and returned after payment either in adjustment of an overcharge or to gain a com-petitive advantage

{

a rebate on an income tax

}

{

a rebate on an insurance premium

}

A discount is a deduction from an amount owed or a price asked in consideration of a cash or prompt payment

{

this bill is subject to 2 percent discount if paid within thirty days

}

It also may denote an advance deduction of the amount of interest payable on a loan or note from the time the loan is made or the note purchased until the due date

{

the bank credited his account with the proceeds of the note less the discount

}

2 inference, conclusion, judgment (see under INFER)

3 Deduction, induction and their corresponding adjectives deductive, inductive are comparable as used in logic to designate forms of reasoning.

Deduction and deductive imply reasoning from premises or propositions antecedently proved or assumed as true or certain and procedure from the general or universal to a particular conclusion; thus, the conclusion that one must die someday is based on the premises that all men are mortal and that one is a man; therefore one infers by deduction or deductive reasoning that one must necessarily be mortal.

Induction and inductive imply reasoning from particular facts to a conclusion that is general or universal in its nature. In its simplest form induction implies a knowledge of every particular and a generalization from these; thus, the conclusion that all of a certain man's books have red bindings is reached by induction or inductive reasoning when one has surveyed his library and has found no exception to this rule. In its more complicated forms, since knowledge of every particular is usually impossible, induction often implies the use of postulates or assumptions which are generally accepted (as the uniformity of nature), more or less tentative conclusions, and constant observation and experiment and reexamination of the evidence. In this sense many of the laws of nature stated in the various sciences are derived by induction, but when these laws are used as premises and become the bases for further inferences, the reasoning becomes deductive.