Imagine an acquaintance invites you to dinner. You could say: “I’d love to come. And just so you know, I’m a vegetarian.” You could also say:”I’d love to come, but I only eat meat that is produced by family farmers.” Then what you do? You’ll probably have to send the host a web link or list of local shops to even make the request intelligible, let alone manageable. This effort be well-placed, but it is certainly more invasive than asking for vegetarian food. Jonathan S. Foer