 We need to refine the conception of experience so as to include unperceived objects and exclude secondary qualities. This might push us towards a more “scientistic” conception of universal experience, on which experience is something like the ideal scientific theory of objects in space and  time.[28]  The form of that theory is a priori determinable from the forms of experience: it will represent persisting substances in a 3-D Euclidean space obeying universal causal laws and in simultaneous mutual interaction. However, the determinate a posteriori content of that theory will be grounded in the perceptions subjects actually have.