In an important post Magicalersatz assserts:
The idea that philosophers should start from first principles, construct premises, and ‘follow the argument where it leads’ without hindrance from emotion or personal perspective is a romantic one. It’s also an absurd one. We all come to the table with biases, presuppositions, and background assumptions – whether we admit it or not. And yes, these types of commitments are present even in ‘the core’.
The fact that her statement can seem just common sense may be a testimony to the way in which ideas from empirical research is permeating our perspectives. And if it doesn’t seem just common sense, you should know that there is a great deal of empirical support for the idea that reason alone isn’t going to get us far. We can and should try very hard to get rid of – or at least mitigate – morally problematic biases, but the idea of a good, substantive philosophy emerging from pure reason is a myth.
The thesis that human beings are not purely rational, even when we think we are being so, started to emerge with a number of researchers in the 1960’s-70’s. The first official attack on the Cartesian conception of reason that has many in Anglo-American philosophy in its grip comes with Damasio’s 1994 Descartes’ Error:
ALTHOUGH I CANNOT tell for certain what sparked my interest in the neural underpinnings of reason, I do know when I became convinced that the traditional views on the nature of rationality could not be correct. I had been advised early in life that sound decisions came from a cool head, that emotions and reason did not mix any more than oil and water. I had grown up accustomed to thinking that the mechanisms of reason existed in a separate province of the mind, where emotion should not be allowed to intrude, and when I thought of the brain behind that mind, I envisioned separate neural systems for reason and emotion. This was a widely held view of the relation between reason and emotion, in mental and neural terms.
In the Introduction of new editions, Damasio notes correctly the now entrenched nature of his views:
I advanced the hypothesis … that emotion was in the loop of reason, and that emotion could assist the reasoning process rather than necessarily disturb it, as was commonly assumed. Today this idea does not cause any raised eyebrows …
Of course, the details are not fully worked out, there are competing hypotheses (dual process pictures, for example) that do not incorporate all his ideas, and so on. BUT in general the demise of the ‘man of reason’ is pretty much a done deal.