Putnam's natural realism and the question of a perceptual interface

According to Hilary Putnam, natural realism is a form of direct realism in the philosophy of perception that promises to help see us past an irresolvable metaphysical dispute between realism and anti-realism. Illumination depends upon the claim that in perception that there is no interface between the cognitive powers of the mind and the causal powers of the world. In the present paper I aim to show that there is a hidden complexity in Putnam's notion of a perceptual interface. On a trivializing reading, Putnam intends only to reject a modern materialist version of the traditional 'veil of ideas'. On a richer reading, he intends also to reject the view that the intentional content of experience is autonomous with respect to the external world. I conclude by suggesting that natural realism is not mere common sense and that its fate is tied to its ability to respond to the skeptical threats that help to motivate the traditional options of realism and antirealism.