1. Concise Guide to Critical Thinking
Chapter 9

2. Science is not technology.
Science is not scientism.
Science is not ideology.

3. The Scientific Method:
Identify the problem or pose a question.
Devise a hypothesis to explain the event or phenomenon.
Derive a test implication or prediction.
Perform the test.
Accept or reject the hypothesis.

4. The Logic of Hypothesis Testing:
The hypothesis disconfirmed—
If H, then C.
not-C.
Therefore, not-H.
The hypothesis confirmed— C.
Therefore, H.

5. Hypothesis Testing No hypothesis can ever be conclusively confirmed.
No hypothesis can ever be conclusively confuted.
Our inability to conclusively confirm or confute a hypothesis does not mean that all hypotheses are equally acceptable.

6. Marks of Good Clinical Trials
Placebo
Control plus experimental group
Double-blind
Randomization
Replication

7. Scientists judge theories with the criteria of adequacy
Testability: Whether there’s some way to determine if a theory is true.
Fruitfulness: The number of novel predictions made.
Scope: The amount of diverse phenomena explained.
Simplicity: The number of assumptions made.
Conservatism: How well a theory fits with existing knowledge.

8. Two Scientific Questions
Copernicus Versus Ptolemy: Geocentric (Earth-centered) vs. the heliocentric (sun-centered) theories of planetary motion.—The criterion of simplicity is the deciding factor.
Evolution Versus Creationism:—The criterion of scope is the most telling of the criteria.

9. Common Mistakes in Assessing “Weird” Theories:
Believing that just because you can’t think of a natural explanation, a phenomenon must be paranormal.
Thinking that just because something seems real, it is real. (A better principle: It’s reasonable to accept the evidence provided by personal experience only if there’s no good reason to doubt it.)

10. Common Mistakes in Assessing “Weird” Theories:
Misunderstanding logical possibility and physical possibility. Also, believing that if something is logically possible, it must be actual.

11. Common Mistakes in Assessing “Weird” Theories:
Logical impossibility:
Something is logically impossible if it violates a principle of logic (that is, it involves a logical contradiction). Something is logically possible if it does not violate a principle of logic (does not involve a logical contradiction).

12. Common Mistakes in Assessing “Weird” Theories:
Physical impossibility:
Something is said to be physically impossible if it violates a law of science.
Scientists are skeptical of any extraordinary phenomenon that is said to be physically impossible.

13. Applying the TEST formula to weird theories
Crop Circles
Talking with the Dead