"No more of those 'dreadful but necessary disturbances,' those 'foolish counselors' leading the rational mind astray. Yet the result of the separation was not the liberation of reason from the thrall of passion. It was the shocking revelation that reason requires passions...... The head can't even do stuff without the heart"
Positing that without the "seething passions" that burn within us we have little to live for. What use is rationality without desire? You can't calculate the value of an action if you have no internal worth assigned to it.
Earlier in the text he compares the difficulty in making highly non-emotional decisions (such as buying a washing machine) and how difficult it would be if all decisions in life were this difficult. He highlights the need in identifying and speaking to the raw emotion within each human soul. Without this connection people simply will not become engaged. When speaking to it, you must be careful to understand the underlying emotional intuition which drives decision making.
Some good commentary I found:
"First of all, Haidt is right that rationality alone cannot be a complete guide to moral behavior, so liberals shouldn't idolize rationality. From early training in mathematics I learned the distinction between axioms, which are statements of first principles, and theorems, which are logical conclusions from the axioms. Reason can provide theorems but it cannot provide axioms. Reason alone cannot tell us which is more important: caring or loyalty, fairness or sanctity, liberty or authority. So what we value needs to be emotionally based. We can try to think through what actions will promote our values in the long run - and even there, as Haidt points out, we are all imperfect.
Second, Haidt is right that loyalty, authority, and sanctity are important moral values for many people. So rather than attacking conservatives for believing in those values, liberals should try to co-opt them. For example, if a corporation closes a working factory in an American town and lays off unionized workers in favor of cheaper labor overseas, liberals can rightly claim that the corporation is being disloyal to its community. If a tar sands oil pipeline threatens to accelerate climate change, liberals can claim that building it disrespects the authority of scientists who have carefully studied its effects. If the same pipeline is likely to spill, liberals can claim that it violates the sanctity of our clean water supply and our natural wonders."