 Bias in a research program is shown to be limiting or partial, but not erroneous, if it avoids clear error and has some empirical successes, while rival theories in the same domain also avoid clear error and have different empirical successes or other epistemic virtues. Such biases are legitimate: it is rationally acceptable to conduct scientific inquiry under their influence. When biases are partial but not erroneous, they serve a generative function, producing new concepts, methods, and hypotheses that open up new aspects of the world for understanding. They are epistemic resources. Feminist philosophers of science argue that we have an epistemic interest in ensuring that certain limiting biases do not dominate research to the exclusion of other generative biases that yield rival theories possessing a different range of important empirical successes. Exposing androcentric and sexist biases lying behind certain theories makes salient the room for alternative programs not based on such biases.