Pinker is wrong.

Lets look at slavery. Is the abolition of slavery anything to do with rationality? No, its a moral argument. In fact most of the abolitionists were strongly religious.

Look at the slaveholder's argument:

'I have a whip, he does not have a whip, therefore I can get him to do as I please and this will give me more wealth'

How do you argue against this rationally? The slaveholder can agree that the slaves quality of life is terrible, but this doesn't affect the 'might is right' argument he is using.

'The strong do what they can and the weak suffer as they must'

You are appealing to his empathy, a human emotion not related to rationality.

Has empathy (the better angels of our nature) generally increased over time? It seems like it.

Possibly, this is due to reduction in the pressures on survival with increasing technical innovation and plenty.

Also, in my view, the rise of the arts. The novel in particular can be powerful empathic brain training.

It might be interesting to compare empathic development differences between novel readers and those that just watch superhero movies.

I like to try and be rational where it is applicable, i.e. where there is data available one can take this into account and try to be impartial in estimating what happened or is likely to happen.

Co-opting 'rationality' as a way of defending ones particular culture is dodgy and can lead to arrogance. I am proud to be part of a culture that values empathy and fairness, its part of my cultural inheritance and becomes part of me. Pretending it is 'rational' is not doing us any favours.

Taking this stance allows us to appreciate that others may be proud of their culture even though we profoundly disagree with them (the Taliban, for instance)

If we regard them as merely 'irrational' then our approach to this cultural difference is likely to be unsophisticated.

Your worship of foragers is nuts. Yes, they are much less hierarchical but they are also extremely conformist.