Arguments by Analogy are

Concept

An argument is deductive when its premises are intended to guarantee its conclusion; it is inductive when its premises make the conclusion more likely without guaranteeing it.

An argument from analogy projects a further similarity from relevant shared similarities, so its support is assessed by degree.

Application

Here, the premises compare two cases and use their shared features to support a further conclusion. Even a strong comparison can leave open the possibility that the conclusion is false, so the support is probabilistic.

Contrast

• Classified as valid: Validity is the standard for deductive arguments in which true premises necessitate the conclusion.

• Classified as invalid: Invalidity is the deductive classification for an argument that does not provide that necessity.

• Claimed to follow from their premises with logical necessity: This describes the aim of a deductive argument, not the graded support of an analogy.

• Probable: This describes an inductive conclusion whose likelihood rises or falls with the relevance and number of similarities.

Cross-check

Ask whether the premises of an analogical argument can be true while its conclusion is false. They can, without contradiction; therefore the conclusion is not logically necessary. Relevant similarities can nevertheless increase its likelihood.

Result

Arguments by analogy support probable conclusions.