There are times when the best thing to do is just shut up and not respond.
With my dad, that's all the time. He is the most stubborn man I've ever met, certain that every thought that comes out of his mind and every word that comes out of his mouth are golden.
I've never been preachy with my veganism (it's only been a little while since I became vegan), but my dad takes every chance to speak out against it. I used to offer counterpoints and try to show him why, but he doesn't listen at all, which can be extremely frustrating at time. For example, we were out having dinner once and I ordered a vegan meal while he ordered a steak with a side of cheesy potatoes, and then criticized me for not eating "real food" (I had a plate full of veggies and a salad).
Since he is convinced he can never be wrong, arguments are futile, even when he has no logical contributions and I have irrefutable evidence to cite. Not wanting to cause a drift in my family, I've given up trying to respond to his jabs at my lifestyle. A new problem seems to have arisen from this strategy, though- he sees my silence as an admission of being wrong. I don't want to continuously defend myself to no avail against someone who won't listen anyway, but I don't want him to tell others that I'm wrong because I don't speak up. My goal is to show by example, leading my cruelty-free and healthy life in peace and letting it speak for itself, but he's chosen to ignore it. I've given up on the idea that he would ever be open to change, but I don't want him to discourage others from seeing the benefits of a healthy and cruelty-free lifestyle just because he doesn't agree with it.
Any suggestions on how to deal with someone like this?