On impartiality, I mostly agree, with one caveat: when you read Hobbes and Rousseau, the social contract is a metaphor. The state of nature serves more like a morality tale, akin to the Garden of Eden, rather than an objective attempt to describe anything. In Hobbes, for example, the ‘acceptance’ of the contract comes from fear and the need for security, not from a 21st-century liberal notion of consent as we would understand it today. It is coerced by necessity. To the extent that they are viable, there are many ways to get what you want from contractualism.
The rest of what you say is precisely the point I am attempting to get at. That obligatory driving force which we associate with morality. The kind that legitimises policies and states and gives purpose to individual lives seems to be irrevocably lost, unfortunately. It is like the old story:
A traveller comes across three bricklayers working on a construction site and asks each of them what they are doing.
The first bricklayer, focused on the immediate task, replies that he is laying bricks.
The second, seeing a larger purpose, responds that he is building a wall.
The third, with the grandest vision, proclaims that he is building the house of the Lord.
That latter kind of purpose is hard to attain with these assumptions. And if you could bottle it, that kind of purpose would be a fruitful resource indeed for EA.
Perhaps there are many in EA. My prior guess would be that many mainstream vegans feel disgust towards animal flesh itself. I know anecdotally that’s how I felt. Motivated as much by considerations of the sacred and the profane and sentiment as anything else. Already empathetic as a person, I was therefore prone to reactions like that.
This is on top of the marketing nightmare of getting people to accept “unnatural, lab-grown meat.” It reminds me of anti-nuclear environmentalist campaigners. And conservationists, motivated by a pristine wilderness that never existed. Sometimes, it is not a rational thing. Emotions and symbols drive things.