Talk of sense data has largely been replaced today by talk of representational perception in a broader sense, and scientific realists typically take perception to be representational and therefore assume that indirect realism is true. But the assumption is philosophical, and arguably little prevents scientific realists from assuming direct realism to be true. In a blog-post on ""Naive realism and color realism"", Hilary Putnam sums up with the following words: "Being an apple is not a natural kind in physics, but it is in biology, recall. Being complex and of no interest to fundamental physics isn't a failure to be "real". I think green is as real as applehood."