The Case of the Missing Premise

I’m interested in enthymemes.

An enthymeme is an argument in which at least one constituent part is not stated, but implied.

When I use the word “argument” I am not denoting a spirited exchange of opinions; rather, I’m using it in a technical sense, meaning “a series of premises leading to a conclusion.”

A simple example of an argument runs as follows:

Premise 1: Sidney Crosby is a human.

Premise 2: All humans are mammals.

Conclusion: Therefore, Sidney Crosby is a mammal.

To turn the above-mentioned syllogism into an enthymeme one could say: “Sidney Crosby is a human, therefore he is a mammal.”

In this case, the second premise, “All humans are mammals” is assumed, but not declared.

If you start looking for enthymemes, you will find them everywhere — on Facebook, in the newspaper, on your cereal box in the morning — albeit not as formally stated as my example.

The success of enthymemes generally relies on an assumption of common sense. For example, the premise “All humans are mammals” doesn’t need to be stated because nearly everyone knows that. If, however, you were aiming this argument at someone who was completely ignorant of biology, it would appear incomplete.

But enthymemes are not always this benign; they can be manipulative. This is done by leading people to believe that an unstated premise is common sense, when in fact it deserves scrutiny and debate. Such a technique is the bread-and-butter of many advertisements.

Consider a typical lottery commercial, perhaps one featuring a yacht in the Pacific Ocean. The argument being made goes like this:

Premise 1: Buying a lottery ticket can make you instantly rich.

Conclusion: You should buy a lottery ticket.

But there’s a missing premise, which is:

Premise 2: Becoming instantly rich will vastly improve your life.

The authors of this enthymeme want viewers to believe that “Becoming instantly rich will vastly improve your life” is common sense in exactly the same way that “All humans are mammals” is.

But is it true that sudden wealth will make you a much happier person?

Maybe, maybe not, but at the very least this missing premise deserves to be analyzed, which is the last thing they want you to do. Spend an evening watching television and tally up the sneaky enthymemes you find.

Not that I am against them; enthymemes are a powerful communication tool. But it is worth noticing when they are being used to trick you — and when you are using them to trick others.

Peter Jickling is a Whitehorse playwright and the assistant editor of What’s Up Yukon

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