Chapter 10 Part 3: Deduction and Induction: A Closer Look

Strong Inductive Argument

If its premises are all true, then its conclusion is probably, although not certain

Weak Inductive Argument

An inductive argument in which it is not the case that if its premises all are true, then its conclusion is probably true; doesn't show that its conclusion is probably true if its premises are all true

Analogical Argument

1. Begins by asserting that two things, “X” and “Y,” have many features in common

2. An additional feature of X is identified (something not known to not be possessed by Y)

3. Conclusion is that Y probably has this feature as well

First Criteria of Analogical Argument

Generally, the more characteristics in common between the things compared, the stronger the analogy, and thus the stronger the argument

Second Criteria of Analogical Arguments

Generally, the more relevant the similar characteristics are to the characteristic described in the conclusion, the stronger the argument

Third Criteria of Analogical Arguments

The larger the number of items analogized in the premises, the stronger the argument

Fourth Criteria of Analogical Arguments

The more diverse the items compared, the stronger the argument, provided that the diversity concerns features unrelated to the feature cited in the conclusion

Degree of Disanalogy; Fifth Criteria of Analogical Arguments

The larger the number of relevant dissimilarities between the items compared, the weaker the argument

Sixth Criteria of Analogical Arguments

Generally, all else being equal, the more specific and narrowly drawn the conclusion, the weaker the argument; the more general and broadly drawn the conclusion, the stronger the argument

Legal Precedent

A judgment or decision of a court that is cited in a subsequent dispute or an analogy to justify deciding a similar case or point of law in the same manner

Enumerative Induction

The premises list or enumerate information about a series of individuals/cases, a pattern is observed, and then a conclusion is drawn that extends that pattern to the next individual case, or to a whole group of like things

Statistical Induction (Generalization From a Sample)

1. N Percent of a sample of a target population have property P

2. Therefore, probably N percent of all the members of the target population have property P

Sample Size

Generally, the larger the sample is in relation to the target group as a whole, the more likely it is that the sample is representative of the group as a whole, and thus the stronger the argument

Sample Variation

Generally, the more varied/heterogenous the sample items, the more likely it is that the sample is representative of the group as a whole, and thus the stronger the argument

Randomness

Generally, the more randomly selected the sample, the stronger the argument

Randomly Selected

When every member of the target population has an equal chance of being in the sample

Biased Sample

When a sample is unrepresentative of the target population

Mean

The arithmetic average of the series

Median

The midpoint of the series; half the values fall above the median and half fall below it

Mode

The value that occurs most often in a series