Perhaps I'm missing something but, [opinion alert] I want to say that I completely agree that laws are the outgrowth of the moral zeitgeist. Given that legal philosophers and justice professors make that very claim I can't see anyway around that. (
Harvard University's Justice With Michael Sandel).
There was a time when slavery was legal and the South felt that the North was trying to push their morals onto them (the south). Segregation. Women's right to vote. Miscegenation laws. What was the basis behind the call for change? Wasn't it moral indignation?
Now, I don't think eating animals is the same as slavery, segregation, women's rights, etc. But let me own that word, "equate", let's use it but point out that I'm drawing a comparison and that comparison is this, there was a time when one group of people felt that slavery should be legal and another didn't. Same here. There are two groups. That's the only "equating" that I'm doing. I'm not trying to say that I (RandFan, meat eater) have the morals of a slave owner.
Since morality isn't objective, religiously or scientifically, who is to say that our views are absolute, or, that some day our morals will be seen by the majority as immoral (not that future popularity would make our current morals wrong)?
I think it fair to grant that vegans have an *ethic and there is nothing untoward behind trying to influence others to agree with their ethic. I think that is the very basis for Hegel's dialectic and free speech, right?
*One that, in the least, seeks to reduce suffering. At least, that's my opinion.