Challenges to rational epistemology

A few approaches stand out to me, were one to begin to argue this claim rather than merely presuppose it.

1. A quick look at the meaning of the word kardia in Greek, which translates both as heart and mind, as compared to nous (intellect) shows how differently this concept has been understood through history. The Orthodox monk St. Theophan famously describes prayer (in its own way an attempt at understanding the cosmos) as standing unceasingly before God holding the mind (nous) IN the heart (kardia)—quite a different position than Descartes'.
2. Support could also be found in evolutionary biology for an understanding of conscious mind as a late development in the human animal—a fragile, plastic thing—which is physically subjugated to the body. All the recent talk about 'emotional intelligence' is getting at this, I believe.
3. Lastly, studies in neuroscience show just how much information the brain has to interpolate from the signals which are physically received through sense input, for example to smooth out rapid but discontinuous motion.