A far as perception is concerned, the only things with which an observer has direct and immediate contact are his or her experiences. - Alan Chalmers

It should be no news to anyone that the perceptual judgements of individuals can be unreliable for a range of reasons. The challenge, in science, is to arrange the observable situation in such a way that the reliance on such judgements is minimised if not eliminated.

Two normal observers viewing the same object from the same place under the same physical circumstances do not necessarily have identical visual experiences, even though the images on their respective retinas may be virtually identical.

The confirmations of novel predictions resulting from bold conjectures are very important in the falsificationist account of the growth of science.