Principles That Function in the Selection
What you must be able to do
Identify the general rule the author is implicitly applying, or select a principle that would justify the author's reasoning if added to the passage.
Concepts to master
- Principle versus evidence. A principle is a general normative or methodological rule ("a theory should be abandoned when a simpler one explains the same data"); evidence is a particular fact. Answers that restate a factual claim are wrong.
- Necessary versus sufficient. Ask whether the principle is offered as a requirement, a guarantee, or a consideration that can be outweighed. "Must" and "only if" principles are strong; "tends to" principles are weak.
- Match the scope of the author's use. If the author applies the rule to interpretation of historical documents, a principle about all human inquiry is broader than needed and usually wrong.
- Direction of support. The principle should support the author's conclusion, not the position the author rejects.
Traps
Absolute principles that would prove too much, principles that justify an opposing view, and choices that paraphrase a premise instead of supplying a rule.
Rule of thumb and worked example
Ask: what would the author say if someone objected? The reply is usually the principle.
Example: the author argues that an interpretation of a fragmentary text should be rejected because it requires emending three separate lines. The functioning principle is something like "an interpretation requiring multiple unsupported corrections to the text is less credible than one requiring none." A choice reading "ancient texts are often corrupted in transmission" is a true background fact but not a rule of judgment.