Why did Bernard Williams believe physical science could pursue a kind of objectivity that ethics could not?

Bernard Williams argued that physical science and ethics operate under fundamentally different aims, making the pursuit of objectivity in science distinct from that in the moral domain.1

In physical science, Williams identified an ambition for an "absolute conception" of reality—a way of describing the world as it exists "anyway," independent of any specific human perspective. While he acknowledged that humans are limited by their own perceptions, he believed it makes sense for science to attempt to identify and compensate for these distortions to reach a single, universal truth.1

Conversely, Williams believed that applying this model to ethics is misguided. Because moral judgments concern how individuals should live and act, they do not represent external, mind-independent entities. He argued that attempting to transcend one's personal perspective to reach a "universal" ethical standard is absurd and self-deceptive, as practical reasons for action must be "internal"—derived from a person's existing motives and contingent, local circumstances. For Williams, ethics is inherently tied to the human point of view, and the ambition to eliminate that perspective undermines the very integrity and meaning of human life.1