analogy

Comparison of two different things, usually made to illustrate or explain complex or unfamiliar ideas. An analogy illustrates the similarity between two different things, for example making an analogy between a person's face and a mask suggests that the face seems artificial or hides something.

An analogy does not have to hold true in all senses, for example if we describe a town as ‘twinned’ with another, we use the analogy of family relationships in order to imply that there is a relationship of sameness and friendliness between the towns. In this sense the analogy holds true. However, the two towns do not share parents and did not necessarily originate at the same time; here the analogy fails.

analogy

In mathematics and logic, a form of argument or process of reasoning from one case to another parallel case. Arguments from analogy generally have the following form: if some event or thing has the properties a and b, and if another event or thing has the properties b and c, then the former event or thing has the property c, too. Arguments from analogy are not always sound and can mislead. False analogies arise when the cases are insufficiently similar to support the reasoning. For example, a whale lives in water and resembles a fish, but we cannot conclude from this that it is a fish. When arguments from analogy are compressed, they are called metaphors.

The design argument for the existence of God is an argument from analogy: it draws an analogy between the properties of order, design, and purpose in a watch, garden, or some other artefact and the universe as a whole. Compare argument from design.