If a theory is untestable, then it isGroup of answer choicesExtremely usefulUseful only in scienceWorthlessUncommon

Analyzing the Question

The question centers around the implications of a theory being untestable and how it can be categorized based on its utility.

Relevant Concepts

1. Testability in Science: A theory should have the ability to be tested through experiments and observations to validate or falsify it.
2. Scientific Utility: The usefulness of a theory is often judged by its ability to produce testable predictions and generate new knowledge.

Analysis and Detail

1. Extremely Useful: This option implies that even untestable theories can provide significant insights or frameworks, but without empirical verification, this is questionable.
2. Useful Only in Science: Suggests that such theories might have some application in scientific contexts but remain fundamentally flawed due to their lack of testability.
3. Worthless: This position holds that if a theory cannot be tested, it lacks any scientific value or practical application.
4. Uncommon: This does not directly address the utility of an untestable theory.

Verify and Summarize

Considering the general view in the scientific community, untestable theories are usually dismissed as they cannot contribute to the empirical progression of science.

Final Answer

The most accurate option is Worthless. An untestable theory fails to provide predictions or insights that can be empirically validated, rendering it of little to no practical use in a scientific context.