But even if all sensations are real, that does not mean that only sensations are real. And the question, "What is real?" was not, I think, asking you only to list the things you think are real, but also to say what it is about all those things that you say are real, that make them real. If I ask you, what is yellow? are you just going to answer, "Butter is yellow"? or will you tell me what yellow is, namely a color of a certain kind. You see the difference. And, even if you tell me that all butter is yellow, that does not mean that only butter is yellow.So even if all sensations are real, that does not mean that only sensations are real, does it?
I would tell you that yellow is a pattern of sensation.
The point is not that only
sensations are real, but rather that nothing beyond our sensations is verifiable. This is tautology. I can only verify what I can experience. Really, the biggest hole is synthetic priori knowledge. I can compile previous knowledge and come to a conclusion about might be the case.
I can't, for instance, directly see particles. I can take in data and its context and draw the conclusion that there are fundamental particles. Where do these deductions spring from though? A posteriori knowledge, or experience, sensation, ect. So what we are doing is simply testing the properties of observable phenomena at a fundamental level. What are the aspects of an object X that are not immediately visable? They influence us in some way, otherwise we could not detect them and their properties (since the type of interaction required for detection is in and of itself a type of influence). The thing still remains, this seems to not come only from sensation, but logic applied to sensation. Is the result really knowledge from sensation alone? Is it possible that the logical possibilities of an object are a physical constituent of said object?
Is it futher possible that the logical form of physical objects is implicit in them, and so our conception of logic is more observational than anything, or is it simply an implicit sense? The former seems to be more reasonable, since the brain is composed of the same fundamental particles as that which we can observe. I have not really been able to resolve this problem to a degree that is even remotely satisfactory.