6. Quoted in GOLDSTEIN & LIEBERMAN at 49.
7. Inductive reasoning is also the main
component of the scientific method—
drawing general conclusions from repeated experiments. A conclusion is not “true,”
only “probably true,” until repeated experimentation makes it established. Even then,
new information can start the process all
over. This is why the “Theory of Evolution,”
despite its scientifically proven validity,
remains a “theory.” See generally CARL
ZIMMER, EVOLUTION: THE TRIUMPH OF AN IDEA
ness, I am
won simply by
for great corporations and
having an income of fifty
thousand dollars. An intellect
great enough to win the prize
needs other food besides
success. The remoter and
more general aspects of the law are
those which give it universal interest.
It is through them that you not only
become a great master in your calling, but connect your subject with the
universe and catch an echo of the
infinite, a glimpse of its unfathomable
process, a hint of the universal law.”
This “hint of the universal law”
suggests that even Holmes was still
theories, intuitions of public policy … even the prejudices which
judges share with their fellow-men, have had a good deal more to
do than the syllogism in determining the rules by which men
should be governed.”
So which is it? Reason or experience?
The answer is both.
Legal logic is a process that involves both deductive reasoning (syllo-
gisms) and inductive reasoning (experience).
Legal Inductive Reasoning
Holmes also wrote,
“Your business as thinkers is to make plainer the way from some
things to the whole of things.”
When judges and lawyers compare cases for resemblances and differ-
ences, they are using inductive reasoning. Stare decisis—treating like
things alike—is inductive reasoning.
7 As Justice Benjamin Cardozo
“The common law does not work from pre-established truths of
universal and inflexible validity to conclusions derived from them
deductively. Its method is inductive and it draws its generalizations
The two types of Inductive Reasoning most relevant to law are
Inductive Generalizations and Analogies.
Inductive Generalization is when we compare a particular thing to the
general. Inductive Generalization takes a sample of a group to conclude
something about the group.
In law we say that “those cases all hold X, therefore this case is
X.” The generalization forms the legal argument asserting that
no specific facts “in the present case” change the outcome.
On using deductive generalization in evidentiary proofs, Dean
John Henry Wigmore gave the classic example:
To show that a certain boiler was not dangerously likely to
explode at a certain pressure of steam, other instances of
non-explosion of boilers at the same pressure would be rel-
evant, provided the other boilers were substantially similar
in type, age, and other circumstances affecting strength.
The Inductive Generalization formula would be,
X percent of observed Fs are A
X percent of all Fs are As
If we were doing a science experiment we could say that
80 percent of observed mice turn green when given
80 percent of all mice will probably turn green when
given the drug.
But the strength of an inductive generalization depends on the
sample. An unrepresentative group is a biased sample.
To be truly valid, a sample should be random, representative
and sufficiently large. What if the poor little “observed” mice
came from a group with a genetic predisposition to turn green?
This would tell us essentially nothing about what the drug
would probably do to all mice. (And this doesn’t even account
for an overenthusiastic grad student with a paint brush!)
Dean Wigmore carefully accounted for this problem when he,
provided the other boilers were substantially similar in type,
age, and other circumstances affecting strength.
Charles Darwin and THE ORIGIN OF SPECIES (1859)
Charles William Eliot
John Henry Wigmore
8. Quoted in RUGGERO J. ALDISERT, WINNING ON
APPEAL: BETTER BRIEFS & ORAL ARGUMENT 277 9. Quoted in ALDISERT at 283.