The a growing body of scientific evidence demonstrating a difference in disgust sensitivity between liberal and conservatives. Evidence suggests that Conservatives have a increased sense of disgust and the following are a few studies that I've pulled from Google Scholar that demonstrate the point.
Indeed, the link appears so strong that fMRI responses to disgust can quite accurately predict political orientation. From the the same paper;
Accumulating evidence suggests that cognition and emotion are deeply intertwined and a view of segregating cognition and emotion is becoming obsolete. People tend to think that their political views are purely cognitive (i.e., rational). However, our results further support the notion that emotional processes are tightly coupled to complex and high-dimensional human belief systems, and such emotional processes might play a much larger role than we currently believe, possibly outside our awareness of its influence. Despite growing evidence from various fields, including genetics, cognitive neuroscience, and psychology, many political scientists remain skeptical of research connecting biological factors with political ideology, arguing variously that biology is irrelevant to central political questions, that the theoretical basis for expecting biology to be relevant is weak and murky that acknowledging a role for biology is reductionist, and that recognizing the relevance of biology to human beliefs and behaviors is potentially dangerous. We hope some of this skepticism can be alleviated from our demonstration that fMRI data, even from a single stimulus, can serve as a strong predictor of political ideology.Smarter neuroscientists are beginning to see that a lot of the political divide is due to a phenomenon known as motivated cognition, in other words the rationalisation hamster justifying emotional response. And a lot of the Left/Right divide may have nothing to do with principled opposition to certain positions rather they are a rationalised gut response to them. Liberals intuitively respond differently to conservatives on many issues. It is not thought per se which is driving the political debate rather it is biocognition.
Furthermore, repeated scientific studies which that conservative and liberals tend to differ on a host of personality factors. Broadly speaking, conservatives prefer order, authority and homogeneity and regularity whilst liberals are more messy and independent. The bottom line is that temperamentally the two groups are different. But it needs to be remembered that this difference needs to be seen as differing along a spectrum rather than being strictly polar.
The philosphical treatment of Rationality tended to view it as a sort of single entity of varying potentcy. i.e. Man was rational, but some men were better rationalists that others. What's becoming apparent in in psychocognitive reasearch is that there are different "modes" of intelligent action and there appear to be different types of intelligence.
Now, here I'm not talking about social or emotional intelligence, rather, there appears to be modes of thinking within the class of activity that we call rational which are different in their natures. The Dual Process theory of the mind postulates that there is a difference with System 1 and System 2. With System 1 being the "intuitive" mode of thought, and the modality of "thought" employed by the average cognitive miser.
The concept I want to explore is the idea of an emotional response being a type 1 type of process, as is the cognition generated by it. So for example, disgust is a type 1 response, as is hypergamy, threat perception, order and novelty preference and so on. Indeed, what makes the difference between liberal and conservative is the type of type 1 response generated by a specific stimulus. One could almost say that conservatives and liberals have different "operating systems" or different "natures" as the old philosophers used to say.
Take for example hypergamy. One of the startling things about the features of the female response to Alpha males is just how consistent it is across cultures. Women prefer the stronger, taller and socially adept male in all cultures and the question is why? The response, much like the response to disgusting stimuli, is not consciously thought out (System 2), rather is intuitively felt. The point being that hypergamy, much like disgust, homophily, preference for fairness and colours are hard wired into our brains. Hypergamy and disgust are a form of "machine cognition" where our biology does our thinking for us with our sensation of it being an emotional (hedonic) response. One way of thinking about it is that the "software" that ensures hypergamic response is front loaded onto the female genome as is part of the female operating system. System 1, to a large degree is what gives us our "natures."
So why is System 1 so important? Because human beings are, by their natures, cognitive misers, and the nature of System 1 "thinking" is to a large extent going to determine the responses humans give to a given question. More on this in later posts.
But it also appears that this type of thinking seems malleable to some degree, particularly through the process of conditioning and can be influenced by externalities to a degree.
I think when all of this stuff is finally nutted out we will see different levels of System 1 malleability. With primal needs which are vital for replication being strongly resistant to change while less "replication contingent" elements of our natures will probably have a significant degree of malleability.