Inductive Reasoning and Evaluation

Overview of Inductive Arguments

Inductive arguments claim that the premises make it likely that a conclusion is the case. They offer probabilistic evidence and can vary in degrees of strength.

Examples of Inductive Reasoning

• Example 1: CNN reported that the roof collapsed on the remaining survivors, killing all four. Therefore, they must all have died.
• Example 2: The water isn't coming out of the faucet. The pipes must have frozen last night when the temperature plummeted.

Evaluating Inductive Arguments

• Strong Argument: The truth of the premises makes the conclusion likely.
• Weak Argument: The truth of the premises does not make the conclusion likely.
• Cogent Argument: A strong inductive argument with all true premises.
• Uncogent Argument: A weak inductive argument, or a strong one with at least one false premise.

Assessing Inductive Arguments

• Strong induction with true premises → Cogent
• Strong induction with false premises → Uncogent
• Weak induction → Uncogent

Types of Inductive Arguments

1. Predictions

The conclusion claims about what will occur or be the case in the future (future contingent).

Example: The spring tide occurs during the full moon. Therefore, it is likely it will occur during tomorrow’s full moon.

2. Causal Inferences

Proceeding from cause to effect, or from effect to cause.

• Example 1: The brownies are undercooked. Therefore, they are gooey.
• Example 2: The brownies didn't rise. Therefore, they had not enough leavening.

3. Argument from Analogy

Depends on a similarity between two states of affairs or events. From some observed similarities, a further similarity is claimed.

Example: Firefighters are like soldiers. You don’t blame firefighters for the fire; one should not blame soldiers for the war.

4. Inductive Generalization

Knowledge of a selected sample provides support for a claim about the whole group. Look for statistical reasoning or polls.

Example: 10,000 men across the U.S. were polled. 85% of respondents claimed they were better looking than average. Therefore, American men believe they are better looking than average.

5. Argument from Authority

Claims a statement is true because an authority, expert, or witness says it is true. (Form: X says p. Therefore, p.)

• Example 1: Marco testified that he saw the defendant shoot the victim and drive away in her Trans Am. Therefore, the defendant shot the victim and left in her vehicle.
• Example 2: Martin Luther King advocated non-violence as the moral means for political protest. Thus, political protest should be non-violent.