These pragmatists distinguish humans from other living organisms in folk psychological terms. The systematic complexity of our beliefs and desires makes us unique amongst life on earth. Pragmatists from Peirce through Rorty portray human inquiry as our effort to improve on our current systems of beliefs and desires. These meliorative efforts, as they describe them, do not require attention to the possibility that our beliefs and desires are so disconnected from the rest of the world that what they are about and what causes us to hold them differ completely from one another. It is, he said, the difference between beliefs held before and beliefs held after the interposition of experimental behavior.
Opinion is what people believed about light, for instance, before Newton's prism experiments.
Knowledge is what they believed after. Opinion is what people believed about falling bodies, to cite another instance, before Galileo's inclined plane experiments. Knowledge is what they believed after. Clearly, this way of differentiating opinion from knowledge dismisses the problem of cosmic estrangement. Newton's and Galileo's experiments do nothing to eliminate the possibility that everything we believe about the rest of the world is false.