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Chapter SixChapter SixThe Persuasive Power of The Persuasive Power of AnalogiesAnalogies

Second Thoughts, 4th ed.Wanda Teays

McGraw-Hill Higher Ed

© 2010. Wanda Teays. All rights reserved.

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Arguments from AnalogyArguments from AnalogyArguments based on an analogy are one

of the most important kinds of inductive reasoning.

An argument from analogy consists of a comparison between two things in which, on the basis of certain similarities, a principle or characteristic of the one term is then applied to the other term and asserted as true in that case as well.

Analogies can be found everywhere from politics to religion and in all aspects of our lives.

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Precedents AnalogiesPrecedents Analogies

In law analogies take the form of precedents.

Precedents are previous cases decided by a court of law or made into law by a legislature. They are widely used by lawyers and judges.

For example: Think how powerful the analogy that’s drawn between obeying the law and baseball. The “three strikes” law, the rules of a game became the model for addressing repeat offenders. However, in the case of criminals, being “out” means 25 years to life in prison.

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FORM FORM OF AN ARGUMENT FROM ANALOGYOF AN ARGUMENT FROM ANALOGY

A is like B in terms of characteristics p, q, r.A also has characteristic “z.”So, B has characterististic “z” also.

EXAMPLE:Keisha is a lot like her sister, Louise—both like

sports, they love scuba diving, and they eat like truck drivers. Keisha thinks she’d like to study the banjo. We might as well get Louise lessons too—no doubt she’ll want to take up the banjo too.

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Garrett Hardin’s AnalogyGarrett Hardin’s AnalogyAbout World HungerAbout World Hunger

Think of our nation as a lifeboat —with 50 people and 10 empty seats.

There are one hundred people (from underdeveloped nations) in the water, trying to get in our lifeboat— To take them all on, we would sink.

If we take a few (how could we choose?), we'd lose our safety margin of the empty seats.

So, we should not rescue any.

This, Hardin argues, is why we are not in a position to help nations with world hunger. We need to preserve our own resources for future use and, thus, should not deplete them by trying (ineffectively, given the numbers) to help.

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James Rachel’s AnalogyJames Rachel’s AnalogyAbout Killing vs. Letting DieAbout Killing vs. Letting Die

He presents two scenarios.In the first case, Smith stands to gain a large inheritance if

anything happened to his 6-year-old cousin. So, Smith drowns the child in the bathtub and makes it look like an accident.

In the second case, Jones also stands to gain if anything happened to his 6-year-old cousin. He sneaks into the bathroom planning to drown him. But, before he can make his move, his cousin slips, hits his head, and falls face down in the water and dies “accidentally” as Jones watches.

Rachel compares Smith’s murder of his cousin with Jones’ failure to intervene. He argues that both are equally morally culpable and there is no significant moral distinction between the two scenarios.

He then applies this to active versus passive euthanasia.. He concludes that terminating the life of a seriously ill person is not morally distinct from “letting them die” by not resuscitating them.

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Assessing an AnalogyAssessing an AnalogyThat's an analogy

Hold it right there! Stop and check it out. Weigh the similarities and differences.

What makes an argument based on an analogy an inductive argument is that the evidence is partial.

In an analogy, the premises only provide some support for the drawing of the conclusion.

If the premises are true, the conclusion that follows an analogy will not certainly be true—it could be false.

This is why an argument from analogy is inductive, not deductive.

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Steps to Analyzing an Steps to Analyzing an AnalogyAnalogy1. Clarify the terms of comparison.2. Note exactly what is being compared to what.3. Write it out like an equation setting out the

comparison. → Sonja/pies she bakes Sonja's mother/pies her mother bakes.

4. State the principle or characteristic attributed to the one term that is being applied to the other term.→ “Sonja’s pies should be as delicious as her mother's pies.”

5. List the similarities.6. List the differences.7. Survey the two lists. Add any omissions to your lists.8. Weigh similarities and differences. 9. Determine the relative strength of the similarities

compared to that of the differences. Some similarities or differences may be more important than others, so prioritize them in terms of relative importance.

10.  Assess the Analogy.  

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Strong vs. Weak Analogies Don’t Forget:

Analogies, like all inductive arguments,fall along a spectrum ranging from dismal to strong.

In a strong analogy, the similarities outweigh the differences. In a weak analogy, the strength of the differences outweighs the similarities.

Ask yourself: Is there a killer difference?Check to see if there is a difference so great that it would outweigh any similarity. If so, the analogy fails.

 

Similarities MAKE an analogy!

Differences BREAK an analogy!

In a false analogy, there are no relevant (nontrivial) similarities at all.

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Assessing the Use of an AnalogyAssessing the Use of an Analogy What is at issue? What principle or conclusion is being drawn from the analogy? Exactly what is being compared?Set out the terms of the analogy.

What are the relevant similarities and differences?List them both.  Assess similarities and differences. Which side is stronger?

How would you attack the analogy? What are its weaknesses? How would you defend the analogy? What are its strengths? Can you make changes to minimize weaknesses and boost

strengths? Note the relative strengths and weaknesses.Decide if the analogy succeeds. 

Remember: Similarities make the analogy. Differences break the analogy.

Close the loop: Does the conclusion (the principle being drawn) follow with credible support from the premises?

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Analogies and Hypothetical Analogies and Hypothetical Reasoning in the LawReasoning in the Law

One of the key issues faced by lawyers and judges is whether a legal precedent applies.

They have to decide how well the letter of the law will apply to a particular case.

A great deal hinges on the relevant similarities, and differences of the precedent case to the case at hand.

To assess this, we have to consider the amount of variation from the standard (norm or precedent-setting case) to the individual one being litigated.

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Using “HYPOS” in Legal Using “HYPOS” in Legal TrainingTraining In order to help prepare a student for the practice

of law, one teaching technique is to use a hypothetical case (alias Hypo).

In hypothetical law cases, a scenario or story is presented, with the task of deciding how it is to be evaluated given the existing laws and precedents.

This is an important application of analogical reasoning!

By analyzing the specifics of the Hypo in relationship to the legal standard, students can then determine how the law should apply in the hypothetical case.

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Potential Legal PrecedentPotential Legal PrecedentResearch. Study the case being litigated. Seek out

the details of the case and determine what legal issues exist.

Examine Potential Precedents. Find cases that are similar. Find potential precedents that:

(a) have strong similarities to show applicability and,

(b) have rulings favorable or useful to the current case.

Show the Analogy Holds. Show strength of similarities merit the application of the principle from the precedent to the present case.

The lawyer can then assert that this new case warrants the same decision.

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The Law and AnalogiesThe Law and Analogies

Presenting Case Case in Question (Note Key Elements)

Analogous Cases Similar earlier cases with(Potential precedents) an acceptable decision.

 Legal principle Decision from earlier cases.

 Application Draw a similar legal principle to

presenting case.

 Assertion Decision Applies to Presenting Case