1 INTELLIGIBLE CAUSATION BY JOHN CAMPBELL Barry Stroud’s The Quest for Reality was based on his John Locke lectures in Oxford in 1987. The book, and the lectures, had a big impact on me. In this essay, I want to try to develop what I take to be Stroud’s main line of thought. In particular, I want to bring out ways in which the argument in The Quest for Reality depends on some arresting doctrines about causation. I will try to show that when we fully think through the kind of picture of causation to which Stroud is appealing, and make explicit its relation to scientific study, we are forced to recognize a kind of ‘intelligible’ causation, that is part of the framework of scientific theorizing, rather than being itself established by and responsible to physics. There is a ‘level’ at which we can describe causal relations that is not susceptible to overthrow by science. It is, I think, quite a compelling picture. Stroud does not highlight the notion of causation in his discussion. My first point is that his argument really does critically involve the idea of cause. 1. Causation in Stroud’s Master Argument In The Quest for Reality Stroud’s main point is that ascription of beliefs about color and experiences of color to a subject depends on the ascriber also being willing to ascribe