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Standard Types: Deductive Arguments

Standard types of arguments include deductive and inductive arguments. Deductive arguments assert that the conclusion necessarily follows from the premises, making the argument valid or invalid. Inductive arguments assert that the premises make the conclusion probable rather than certain, making the argument strong or weak. Both deductive and inductive arguments can be evaluated based on whether their premises are true or false, affecting whether they are sound, unsound, cogent, or uncogent.

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122 views2 pages

Standard Types: Deductive Arguments

Standard types of arguments include deductive and inductive arguments. Deductive arguments assert that the conclusion necessarily follows from the premises, making the argument valid or invalid. Inductive arguments assert that the premises make the conclusion probable rather than certain, making the argument strong or weak. Both deductive and inductive arguments can be evaluated based on whether their premises are true or false, affecting whether they are sound, unsound, cogent, or uncogent.

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MJ Botor
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Standard types

Argument terminology

There are several kinds of arguments in logic, the best-known of which are "deductive" and
"inductive." An argument has one or more premises but only one conclusion. Each premise and the
conclusion are truth bearers or "truth-candidates", each capable of being either true or false (but not
both). These truth values bear on the terminology used with arguments.

Deductive arguments
A deductive argument asserts that the truth of the conclusion is a logical consequence of the
premises. Based on the premises, the conclusion follows necessarily (with certainty). For
example, given premises that A=B and B=C, then the conclusion follows necessarily that A=C.
Deductive arguments are sometimes referred to as "truth-preserving" arguments.
A deductive argument is said to be valid or invalid. If one assumes the premises to be true
(ignoring their actual truth values), would the conclusion follow with certainty? If yes, the
argument is valid. Otherwise, it is invalid. In determining validity, the structure of the argument is
essential to the determination, not the actual truth values. For example, consider the argument
that because bats can fly (premise=true), and all flying creatures are birds (premise=false),
therefore bats are birds (conclusion=false). If we assume the premises are true, the conclusion
follows necessarily, and thus it is a valid argument.
If a deductive argument is valid and its premises are all true, then it is also referred to as sound.
Otherwise, it is unsound, as in the "bats are birds" example.
Inductive arguments
An inductive argument, on the other hand, asserts that the truth of the conclusion is supported to
some degree of probability by the premises. For example, given that the U.S. military budget is
the largest in the world (premise=true), then it is probable that it will remain so for the next 10
years (conclusion=true). Arguments that involve predictions are inductive, as the future is
uncertain.
An inductive argument is said to be strong or weak. If the premises of an inductive argument
are assumed true, is it probable the conclusion is also true? If so, the argument is strong.
Otherwise, it is weak.
A strong argument is said to be cogent if it has all true premises. Otherwise, the argument is
uncogent. The military budget argument example above is a strong, cogent argument.
Deductive
Main article: Deductive argument
A deductive argument is one that, if valid, has a conclusion that is entailed by its premises. In other
words, the truth of the conclusion is a logical consequence of the premisesif the premises are true,
then the conclusion must be true. It would be self-contradictory to assert the premises and deny the
conclusion, because the negation of the conclusion is contradictory to the truth of the premises.

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