Background: My parents have recently changed to a vegan diet. They've discovered a lot of books, websites, and videos providing scientifically-backed reasons to eat only plant-based foods, and cut out animal products entirely. Since becoming vegans, both my parents feel great.

A family we are best friends with is heavily into nutrition. They have a huge focus on removing toxins from their diet, which can be traced back to causing a lot of health problems. They are very knowledgeable about this field.

I'm excited about eating better. The trouble is that the friends I mentioned above don't believe in vegan-ism. They think the idea that foods like milk, eggs, and organic grass-fed meat are bad for you, is laughable.

I really respect the knowledge these people have in the field of nutrition. They know a lot of stuff, and they've applied it to their own lives. But they disagree with the idea of going vegan.

Goal: I would like to reconcile the discrepancies between the science-backed pro- and anti-vegan information I've discovered. On one side there are doctors and nutritional experts saying all animal products are bad for you for a host of reasons. On the other side are my best friends - who, though not professionally, really are nutritional experts all the same - saying that not eating animal products is a bunch of baloney.

The simplest way I see to reconcile these differences is to show my friends the evidence we've found, and have them explain to me why it is faulty or correct. I'm not trying to convert them. I'm just trying to understand for myself.

Problem: My dad doesn't want me to do this. I've brought up my desire to show our friends the evidence and have them explain it to us, and his reply is always the same:

"They don't want to hear it; I don't want to force it on them. I don't want you to bring it up."

There is no transition in the conversation. Whenever I mention it, he shuts me down with more or less that exact line. The problem here is that I don't think he understands what I want to do. I'm not trying to convince anyone, I'm just trying to understand myself.

If they really didn't want to hear about it, that would be one thing, but I've seen nothing to suggest that. In fact, they bring it up themselves from time to time. However, trying to explain this and/or what I really want to do gets me nowhere with my dad.

My dad isn't really the kind of person you can have a logical debate with. You can try, but once you run into something he disagrees with, he starts getting invested in it. If you keep pushing, he starts jumping to conclusions about what you are saying ("So you want to do __?!?"), which normally isn't what I'm saying at all. If I keep pushing, he just shuts me down, saying he doesn't want to hear it, or acting like I'm being stubborn and talking won't solve anything. This makes trying to explain something to him - something which he disagrees with - nearly impossible. Unless there's another method.

So that's really what I'm asking: How can I explain something to someone who assumes I mean something else, and just shuts me down?

_{Please note that this is not a question about veganism, but a question about how to explain something to someone who doesn't want to hear it.}