What does the Law of Parsimony state?

• A. The most complex theory is usually the most accurate.
• B. When two theories make the same predictions, the one that is simpler is more likely to be accurate
• C. The theory with the most data is always correct
• D. Unrelated theories cannot be compared

Answer: (B)

The main idea here is that we should prefer the simplest explanation that accounts for the observed facts. The Law of Parsimony, often called Occam’s Razor, suggests that if two theories explain the same phenomena equally well, the one with fewer assumptions is more likely to be correct, because it makes fewer places for error and is easier to test.

That’s why the statement stating that when two theories make the same predictions, the simpler one is more likely to be accurate is the best choice. It captures the practical logic behind parsimony: unnecessary complexity doesn’t boost truthfulness, it just adds potential for error.

The other notions run counter to this approach. Favoring the most complex theory isn’t supported by parsimony because extra complexity isn’t inherently more accurate. Believing the theory with the most data is always correct ignores the quality and relevance of that data and whether the theory actually explains and predicts outcomes. And saying unrelated theories cannot be compared ignores the very process of evaluating competing explanations based on how well they account for observations and predictions.