Chapter 3, “Arguments by Analogy” pp. 19-22
Weston’s rule number seven was, “Use more than one example.” However, an argument by analogy uses only one specific example, “reasoning that because the two examples are alike in many ways, they are also alike in one further specific way” (Weston 2009, 19). Weston uses the analogy of automotive servicing and medical checkups as an example. Weston helps evaluate the structure of an argument by analogy. The first premise must be true. For instance, it must be true that cars need regular service if that will be used as an analogy (Ibid., 20). The second premise must actually be like the first one. Weston gives rule #12, “Analogies require relevantly similar examples” (Ibid., 21). In the automotive example, though it is not true that human bodies and cars are alike, the analogy depends on both being complex systems, a fact which is similar.