Evaluation requires judgment. When evaluating an analogical argument, it is important to remember that analogies can be found in deductive or inductive reasoning. An inductive conclusion should contain the word "probably." Understanding analogy form and fallacies can help you evaluate the quality of analogical argumentation.
Things You'll Need
- Logic term glossary
- Fallacy list
In order to evaluate, you need to know basic structure of inductive and deductive reasoning. Arguments may be inductive (specific to more general) or deductive (general to specific). They begin with premises and end with conclusions. For example in induction, one premise might state X has qualities A, B, and C. Another premise Y has qualities A and B. The conclusion is therefore, it is likely Y has quality C. In deduction, the pattern has three statements. All A are like B. B has a certain characteristic. Therefore, A also has this characteristic.
Evaluate if premises have credibility and plausibility. Because induction is based on generalizing from specifics, it is important to evaluate how accurate the premises are. Did the researchers devising the premises only examine their region when gathering data but make a universal claim? If so, the argument would be considered weak. Generally, the larger the sample of the population observed, the more accurate and reliable the premises.
Evaluate analogies as strong or weak in on the strength of premise similarity. The following is an example of a strong analogy. Premise: Learning logic is like learning statistics. Premise: You can't learn statistics by cramming; you have to study it consistently. Conclusion: You probably can't learn logic by cramming; you have to study it consistently. Analogies that try to compare unlike items are inherently weak.
Evaluate analogical arguments by premise analysis. Both the major and the minor premise need to be valid statements for the conclusion to have truth. A classic syllogism has two premises and a conclusion: All men are mortal. Aristotle is a man. Therefore, Aristotle is mortal. In deductive reasoning the term "soundness" means the argument is strong. If the premises are true and the analogical form correct, the conclusion will be valid.
Recognize false analogies to evaluate the strength of analogical argumentation. A false analogy is a comparison that is weak or inappropriate. This occurs when the comparison is based on only a few similarities or if the comparison has a misunderstanding, ambiguity or sweeping generalities. The following is an example of a false analogy: College is much like high school. Each has classes based on distinctive subjects. Each has a different teacher for those subjects. Therefore, there is no difference between college and high school.
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