The Fallacy of Similarity

On an October evening in 1988 in Omaha, Nebraska, two U.S. Senators engaged in a televised debate as candidates to be the Vice President of the United States. When questioned about his youth and level of experience, Dan Quayle commented, “I have as much experience in the Congress as Jack Kennedy did when he sought the presidency.”

His opponent, Senator Lloyd Bentsen responded, “Senator, I served with Jack Kennedy. I knew Jack Kennedy. Jack Kennedy was a friend of mine. Senator, you’re no Jack Kennedy.”

Bentsen received tremendous applause at the clever lines. While he was clever, Bentsen did commit one of the most famous fallacies of similarities. I have not read of this fallacy anywhere. It is something that I have observed for some time. It especially pops up in debates, arguments and fights.

Here is what I mean by the fallacy of similarity. One person invokes two separate nouns at a single point of comparison. That is, two nouns may share an adjective. The second person commits a fallacious argument when he/she attempts to join the two nouns with all adjectives that might apply to one of the nouns.

An example would be for person A to state, “This apple is as red as a fire truck.” In making this statement, person A is only comparing the color of the two nouns. Both are red.

Person B may legitimately question whether the two objects are indeed red. Evidence might be cited to suggest that apples are green and fire trucks are yellow. Thus, his argument would call into question the statement of person A.

However, Person B cannot legitimately question person A’s statement by arguing that apples have seeds while fire trucks do not. Senator Quayle could compare himself to Jack Kennedy in years of experience in Congress. By so doing, he was not claiming a Massachusetts home, marriage to Jackie O, nor conflict with Nikita Kruschev.

The fallacy also occurs when the second person in the debate assumes that the first person is attributing the same importance to both items in comparison. If I say that my football jersey number was 12 like Roger Staubach, I am not claiming to be a Heisman trophy winner and Super Bowl champion quarterback like Staubach. Being a #12 quarterback for the Sapulpa Chieftains was a little less important than being a #12 quarterback for the Dallas Cowboys.

One of the most common usages of this fallacy relates to Adolf Hitler and Nazi Germany. If one states that anybody or any group has any point of comparison to Hitler or the Nazis, the response is almost automatic, “Are you calling me/us Hitler or Nazis?” The answer is clearly no.
When somebody offers a point of similarity or comparison, please do not fall into this fallacy of similarity. You might win some applause from the peanut gallery, but you will either begin or continue an argument.

Please note: I reserve the right to delete comments that are offensive or off-topic.