Chapter 11 Lecture Notes
Analogies: Reasoning from
Case to Case
Chapter 11
In this chapter we deal with analogies. They are a powerful
and plentiful argument form in the law, psychology, and
medicine.
There are many uses for analogies other than argument,
and one such use is explanatory. Someone might use
an analogy to explain how something works. This often
happen in theoretical physics and other more mundane
physical devices.
Analogies can also be used to create interest and make
descriptions of things that are unfamiliar.
Chapter 11
Analogy and Consistency
Treating relevantly similar cases similarly is a fundamental
aspect of rationality (320). This general principle of
rationality is one of the engines that makes analogies
run.
An appeal to consistency is just an attempt to treat
relevantly similar cases similar. We do this in the law,
disciplining out children, and any other relevantly similar
case we might encounter.
Chapter 11
Analogies have some basic parts:
The analogue(s): the thing to which the primary subject is
compared (there may be multiple analogues in an
argument by analogy)
The primary subject: this is the topic about which one
derives a conclusion in an argument by analogy.
The conclusion of the analogy: the is the main point or
claim of the analogy.
Chapter 11
When we treat similar cases similarly, we are acting
rationally, and this kind of behavior is the basis of the
legal system.
Consistency in reasoning is the basis of the precedent
system of law (322).
In order to preserve justice we must treat similar cases
similarly and this is just want analogical reasoning
attempts to do.
Chapter 11
Starting with agreed upon cases allows for certain kinds of
analogies, which typically deal with conceptual cases.
The general form of this kind of argument is:
1. The analogue has features a, b, and c.
2. The primary subjects has features a, b, and c.
3. It is by virtues of features a, b, and c that the analogue
is properly classified as a W.
So,
4. The primary subject out to be classified as a W.
Chapter 11
Often arguments will make an implicit appeal for consistent
treatment of cases with words or phrases like the
following:
(i)
(ii)
(iii)
(iv)
That’s just like saying
You might as well say
By the same reasoning
According to those standards
What we find in language is a real understanding of the
analogy without a formal analysis. Most of us know
about consistency and fairness on a gut level. If not,
you can always appeal to a small child for fairness.
Chapter 11
Refutation by Logical Analogy:
Sometimes you can show that an argument is poor by
comparing it with another, similar argument that is poor.
When this occurs we say the argument was refuted by the
use of a logical analogy. Sometimes we refer to it as a
parallel case.
For a clear case where an anti-prescription drug argument
is refuted with an ice-cream argument on page 325.
Chapter 11
Often an analogy is offered where the premises (and the
analogue) are fictitious or hypothetical. This, however, is
not a problem to the cogency of the analogy.
As long as the analogy is set and clear, then we can make
a decision about similar cases in a reasonable way. We
don’t need actual similar cases to make the points we
need to when evaluating or presenting an analogy.
We we present analogies where the analogue is
hypothetical, we call these a priori analogies.
Chapter 11
Cases of a priori analogies should be evaluated using the
ARG conditions as our other arguments. The difference
between the a priori analogies and the inductive
analogies will be made clear below.
To evaluate an a priori analogy, you have to look at the
intended conclusions and reflect on the relevant
similarities and differences between the primary subject
and the analogue (328).
Are the relevant and sufficient to support the conclusion?
Chapter 11
Inductive Analogies:
In an inductive analogy, the analogue must be a real case.
An inductive analogy is based on the factual similarities
between the analogue and the primary subject.
A classic example of inductive analogies deal with
inferences about drug trials that occur in rats that is then
abstracted to claims about use in humans. See pages
333 on for a detailed example.
Chapter 11
One way to object to an analogy is to provide what one
might call a counteranalogy.
A counteranalogy typically points out a relevant property
that that is different than the original analogy. When this
happens there is typically a new conclusion that is the
opposite of the original conclusion.
Couteranalogies when well formed will constitute a
powerful criticism of the original analogy.
Chapter 11
Loose and Misleading Analogies:
The fallacy of the faulty analogy occurs when the analogy
is so loose and remote that there is virtually no support
for the conclusion.
The fallacy of two wrongs make a right occurs when an
analogy is used to show two things that are wrong are
similar and one is tolerated and so the other should be
tolerated. This is to misuse the appeal to consistency.
(341).
Chapter 11
The fallacy of Slippery Assimilation:
This is another misuse of the appeal to consistency. It is
an argument where because things are arranged in a
series, where there is very little difference between each
member in the series, that the cases should be treated
the same.
Imagine a line of children all one millimeter different in
height. There isn’t much of a difference between each
one, but at some point one child isn’t tall enough to get
on the amusement ride. It is a mistake to treat them all
the same.
Chapter 11
The Fallacy of Slippery Precedent:
Slippery precedent argument cite a series of cases and use
it to argue for a conclusion about a first case in the
series, alleging that a slippery path will make it easy to
slide from one case to another.
The original action is good, but is compared to a bad
action. The mistake is that good actions aren’t relevantly
similar to bad actions to make the argument cogent. For
a detailed example see page 344-5.
Chapter 11
Term to review:
Analogue
Analogy
Appeals to consistency
A priori analogy
Conceptual issues
Counteranalogy
Fallacy of slippery assimilation
Fallacy of slippery precedent
Fallacy of two wrongs make a right
Inductive analogy
Precedent
Primary subject
Refutation by logical analogy