2. Let’s review what an inductive
argument is.
Any argument whose premises may provide evidence for
its conclusion or hypothesis but do not guarantee it.
Here’s an example of an inductive argument:
1. Pam is athletic.
2. Most of those who are athletic don’t eat junk food.
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3. Pam doesn’t eat junk food.
3. To determine whether an argument
is inductive, consider:
• whether it would be possible for an argument
with the same form to have true premises and
a false conclusion
• whether one can assert its premises and deny
its conclusion without contradiction
• whether the conclusion adds information not
contained in the premises
5. Enumerative Induction
Always has a universal conclusion to the effect
that all things of a certain kind have (or lack) a
certain feature. This conclusion is drawn from
evidence that some things of that kind have (or
lack) that feature.
The conclusion of this type of argument, often
called an inductive generalization, is a universal
generalization.
6. Enumerative induction attempts to support universal
generalizations by using non-universal generalizations
or specific statement as premises.
1. Many roses have been observed to blossom in the summer.
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2. All roses blossom in the summer.
--or--
1. Rose 1 has been observed to blossom in the summer.
2. Rose 2 has been observed to blossom in the summer.
3. Rose 3 has been observed to blossom in the summer. . .
4. Rose number n, has been observed to blossom in the summer.
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5. All roses blossom in the summer.
7. So what’s a universal generalization?
A statement asserting that all of the members of a certain
class have (or don’t have) a certain feature.
May be expressed by a great number of different patterns
of sentence.
Some standard patterns:
• “all . . . are”
• “every . . . is”
• “no . . . is”
8. Non-Universal Generalization
A statement asserting that some, perhaps many, of the
members of a class have (or don’t have) a certain
feature.
May be expressed by a great number of different
patterns of sentence. Some standard patterns:
• “most . . . are”
• “a few . . . are”
• “many . . . are”
• “n percent of . . . are” (where n is less than 100%)
• “some . . . are”
• “some . . . are not”
9. Statistical Syllogism
A statistical syllogism is an inductive argument
whereby a certain feature is ascribed to a case or
cases on the basis of their being subsumed within
a larger class of things, some of which, perhaps
many, have the ascribed feature.
1. Most surgeons carry malpractice insurance.
2. Dr. Hagopian is a surgeon.
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3. Dr. Hagopian carries malpractice insurance.
10. Causal Argument
According to the textbook, a causal argument
makes the claim that two or more things or
events are causally related in either of these
ways:
• Effect E results from cause C.
• C causes E.
• E and C are the cause or the effect of another
thing X.
12. Examples of Causal Arguments
• HIV causes AIDS.
• Having the genome of a cat causes Fluffy
the kitten to grow up to be a cat.
13. Three Meanings of Cause
• Sufficient Cause: C is a sufficient cause of E
if, and only if, C always produces E.
• Necessary Cause: C is a necessary cause of
E if, and only if, E cannot occur in the
absence of C.
• Necessary and Sufficient Cause: C is a
necessary and sufficient cause of E if, and
only if, C always is the sole cause of E.
14. Analogy
Analogy is a type of inductive argument whereby a
certain conclusion about individuals, qualities, or
classes is drawn on the basis of some similarities with
other individuals, qualities, or classes.
Whether an analogy succeeds depends on:
• the number of things and the number of features held to be
analogous
• the degree of similarity or dissimilarity among those things
• the relevance of ascribed features to the hypothesis
• the boldness of the hypothesis with respect to the evidence
15. Here’s an example of an Analogical
Argument:
This is the argument’s form:
16. Criteria for Inductive Argument
Evaluation
Reliability
Concerns argument form and is, in this respect, comparable
to validity for deductive arguments.
In a reliable argument, the relation of premises to conclusion
is such that, if all the premises were true, it would be
reasonable to accept the conclusion.
Strength
Requires that the inductive argument be reliable and have
true premises (compare deductive soundness). When an
argument is inductively strong, it’s reasonable to accept its
conclusion.
17. The “Cash Value” of Reliability
and Strength
Inductive Reliability’s Cash Value
If an argument has a good share of reliability, then it would be
reasonable to accept its conclusion, provided that its premises are
true.
Inductive Strength’s Cash Value
If an argument has a good share of inductive strength, then it’s
reasonable to accept its conclusion, since it has a reliable form and
its premises are true.
