Analogies Whereas similes and metaphors compare things that are essentially different except for one similarity, analogical arguments compare things that are alike in all essential respects and then claimed to be alike in some further respect. From the Greek, ana logon, “according to a ratio,” analogies declare a relationship between two things, a parallel connection, usually between ideas or a set of ideas. In mathematics, for example: 5 is to 10 as 10 is to X. X being 20. Or, up is to down as right is to? Left, because the relationship is one of opposites. These are analogy questions.

Analogies II An analogy is a comparison of things based on similarities those things share. Although analogies are interesting and important for many reasons, including their use in poetry, we shall focus on one: their importance in constructing inductive arguments. Arguments from analogy claim that certain similarities are evidence that there is another similarity.

Analogies III Extended beyond mathematics, analogical reasoning has had an extremely wide application. For instance, physical scientists have argued that the atomic nucleus is like a miniature solar system, so whatever physical forces disrupt the one will disrupt the other. Just prior to the Revolutionary War some royalists argued that the colonies were like the children of the mother country, and just as children should remain loyal to their parents, the colonies should not revolt against England. On the other hand, the revolutionaries argued that the colonies were like fruit in an arbor, and when the fruit is ripe it is natural that it should drop from the tree.

Analogies IV These examples illustrate the nature of analogical argument, but the last example also shows one of its basic weaknesses. That is, almost anything can be proven by carefully selecting the comparison. If we want to argue for the blessings of old age we can compare it to the maturing of a fine wine or say that one achieves senior status in the community acquires patience and wisdom, free from the tyranny of passions. On the other hand, we could show the sadness of old age by comparing it to a house that is decrepit and crumbling, a pitiful ruin dimply reflecting its former dignity.

Analogies V The English theologian William Paley ( ) presented one of the best known analogical arguments. Paley tried to support the view of St. Thomas Aquinas that the world exhibits evidence of a purposeful design and therefore proves the existence of an intelligent designer, that is, God. Paley did this by comparing the world to the mechanism of a watch. If we were on a deserted island and found a watch ticking away in perfect order, we would assume that a watchmaker had produced the watch. The odds of all the random parts coming together and forming a functioning watch by pure dumb luck seems unlikely. In the same way, it is unlikely that just dumb luck and a big bang could create a world such as this that is well- organized and functional.

Analogies VI However, we could also compare the world to an organism rather than a mechanism, one with biological parts that can become diseased; with systems, vital organs, and limbs that develop and degenerate; and with energy and matter at the core, not mind or spirit. The blind watchmaker.

Analogy and Induction In an inductive generalization, we generalize from a sample of a class or population to the entire class or population. In an analogical argument, we “generalize” from a sample of a class or population to another member of the class or population.

Criteria for determining the strength of analogical arguments 1.The two cases must be alike in all essential respects, and the greater the relevant similarities the more probable the argument. For example: – Jim and Tim are both burly and play football. – Jim also wrestles. – So, Tim must also wrestle. This is obviously a weak analogy. It would be made stronger if it was noted that they are best friends, rarely do anything apart, attend a college that gives scholarships only to athletes who play more than one sport, and so forth.

Criteria for determining the strength of analogical arguments II 2.The greater the number of cases compared, the stronger the probability of the conclusion. For example: Jim’s Buick leaks oil. Therefore, Tim’s Buick will leak oil, also. This case is not enough to make a fair statement. If we tested 5,000 Buick cars and all of them leaked oil, then we would have a stronger case.

Criteria for determining the strength of analogical arguments III 3.The greater the dissimilarity of the cases used as the base of the analogy, the higher the probability of the conclusion. Example in the book: If we say that a company is like a football team in that they are both organizations of individuals devoted to the achievement of a common goal, and just as teamwork is necessary in winning football so teamwork is essential to business success. If the characteristics applied to high school teams, as well as college teams, professional and amateur, and so forth, that is stronger evidence than citing just one football team.

Criteria for determining the strength of analogical arguments IV That is to say, if all subsets exhibit the same characteristics plus the factor of teamwork, then the argument that business (which is similar to them) should do likewise and becomes more powerful. If all three rules are followed, the likelihood of the analogy being correct is increased considerably, although we can never be certain of our conclusion.