The first time I opened Peter Singer’s “Animal Liberation,” I was dining alone at the Palm, trying to enjoy a rib-eye steak cooked medium-rare. If this sounds like a good recipe for cognitive dissonance (if not indigestion), that was sort of the idea. Preposterous as it might seem, to supporters of animal rights, what I was doing was tantamount to reading “Uncle Tom’s Cabin” on a plantation in the Deep South in 1852.