Critical Thinking & Information Literacy
Across the Curriculum
Reasoning by Analogy
Philosophy 115 Assignment 9:
Arguments from analogy are particularly prevalent in legal reasoning and moral reasoning.
The purpose of this assignment is to help students identify and evaluate arguments from
analogy that are a part of an article or more complex argument.
For this exercise, the Instructor can use Judith Jarvis Thomson’s article “In Defense
of Abortion,” or any court opinion or article that involves arguments from analogy.
There is some disagreement (at least among philosophers) about whether Thomson’s
article is best interpreted as a series of analogies. Regardless, I think this
article is fun for students and many of the examples she discusses can be seen
as analogies (even if that is not the best interpretation of them from a philosophical
point of view).
In the article, Thomson can be seen as giving several analogies that attempt to show
that there are at least some cases in which abortion is not morally wrong.
Students should read the article and try to find at least one argument from analogy
they take Thomson to be making. They should then attempt to reconstruct and
evaluate the analogy by answering the following questions:
1. What are the two cases that are being compared in this argument?
2. What are the attributes or characteristics that these cases are assumed to have
in common? That is, what characteristics can we easily agree these two cases share?
3. What is the further attribute that the author wants us to infer these cases share?
4. Is the argument from analogy a good one? In evaluating the analogy, you will want
Do the two cases have enough similarities to make the argument strong?
Are the similarities relevant to the characteristic that they are inferred to share?
Are there any dissimilarities between the cases that undermine the analogy?
Is there any way that the analogy could be strengthened?