Positive rat facts

Useful positive facts (Some from quick searches):
They're pets with huge meaning. They're no different than dogs in the way we love and cherish them.
They're extremely clean animals.
They're said to be on par with dogs in their intelligence.
They bring us joy. <3

Random facts:
They can laugh.
They feel many of the same emotions we do, such as depression, anxiety, and regret.
They will get lonely and depressed without their mommy.

Myths:
They are clean.
They're not absolutely massive.

Some things you may want to console your father about:
You will watch them carefully.
They will not crawl into the walls/destroy everything.
You will not lose them in the house.
Anything they may break with be replaced by you.
Their cage will be clean and will not stink up the house (Of course, there will be a general animal smell that cannot be avoided.)
They are extremely important to you and leaving them behind would be like abandoning a young family member to someone else.

Honesly, I don't think quoting a list is the way I'd go... As someone that's done complicated sales all my life, the first rule to getting a sale is to identify a customer's objections and overcome them.

Find out why your dad doesn't like your rats and then deal with those issues specifically. My wife is rat phobic and no one can fix that problem, but she lets us have rats... We overcame the objections with proving that our rats don't bite and by setting up barricades around the house so the wife and the rats can free range in different areas or on different floors. And she understands that my daughter needs pets. No it wasn't easy and it's never going to get easy, but we handle one issue or objection at a time. After some years of living with rats, my wife still stands on a chair when the rats are out and she comes to my office, but she doesn't shriek or scream when she sees one and the rats understand what "go away" means and to avoid the crazy lady when she's around...

Sure I could have tried to sell all the benefits of rats, and how they are misunderstood but that wouldn't have worked. My wife watched our daughter snuggling with the rats, and she even remarked how the rats loved our little girl. But that couldn't help with her phobia, whereas barricades work a treat. Once you understand your dad's reasonable objections, you can address and overcome them. Sometimes it takes a good argument, and sometimes it takes some plywood.

I didn't always get along with my dad, to be honest we didn't understand each other even when we got along. Some day I expect that my daughter won't understand me, and maybe I won't understand her choices either.... Maybe I'll be stupid enough to try and fix her, like my dad tried to fix me... But as a dad, I love my daughter and I know my dad loved me too. The more we try to help one another the more we're likely to fight, it's in our DNA, a giant cosmic joke.

As a dad, for better or worse, that's the best advise I can give you. I'm not saying it's going to help, but start out by telling your dad you love him and ask him what you can do to make it work with you and your rats in his house... maybe you can work out a compromise...

If that doesn't work you can still read off your list of rat benefits, it will give you time to cool down and work out another strategy.

Best luck.

Up until I was 55 I always thought rats were "EWWWWW!". If I happened to see someone somewhere with a pet rat, I managed to ignore their presence. My mother had had a livelong fear of rats and mice and I learned by her example. Then one day I saw a program about rats on Animal Planet. Part of the program was to show a Siamese and a naked rat. This sparked my curiosity on just what colors pet rats come in, and that search opened my eyes to so much more. In the years since, I have had a mixed mischief of 13 (spayed/neutered) rats and several sets of 2 or 3 rats. I have introduced others to rats. I was in the Red Hats and when it was my turn to sponsor an activity, I set up a visit to a local rat rescue. Only 4 people other than my sister and me attended. Of that 4 - 1 had had rats before, 2 were interested in what we had to say, 1 had to be there (a member of the officers had to attend and the other, superior officer refused) and said we could see the rats, but she was going to stay as far away as possible. Later I looked and she was playing with the rats in the background. Over the years I have found that open minded people are willing to look and see what we are talking about, some that appear close minded are willing to change their minds, but truly close minded people are not going to listen, period. So, it really depends on where on this line your father is. If he is willing to listen, then you can proceed. If he will not listen, then you are stuck. If he will listen, perhaps he would be willing to meet one of your rats and see what you see in them. You know your father better than any of us. I hope you can find a way to open up communication and get past this with him. Good luck.

What if someone else held the conversation with your father? Would your husband be willing to do it? I agree with Rat Daddy that overcoming the negatives may be more effectual than listing the positives. All the pretty words in the world will do nothing if someone still has objections. You have to undermine those objections and make him realize that they are unfounded.

Unfortunately, it sounds like if you attempt it, then things will shut down. You'll present a perfectly rational explanation of why his objection doesn't hold water. Being human, he'll probably attempt to counter, deflect, or just outright deny your argument. I imagine this will infuriate you, and you'll say something hurtful and irrelevant to the conversation. Try a mediator, but don't hang around; if you're the type to jump in with snark, then that is just as unproductive.

So assuming your husband agrees (or you have someone else), have him explain that these rats are your babies. Just like a good mother wouldn't let her children just run around and stomp on everything, you would not let your rats destroy the house. Have your husband present pictures of the barriers you use to keep the rats together, though honestly if he doesn't know that rats can free-range, I wouldn't bring that up; he might be more comfortable about the rats if he thought they were always locked up. Have your husband show how secure the cage is, so he doesn't have to worry about rats getting out at night.

If you are able to overcome his objections, then positive facts may help out, but you two are so incredibly close that you cannot have an objective conversation with him. Consider an envoy.