You can’t.
That’s because toddlers don’t understand what an argument is and aren’t interesting in having one.
Toddlers (which includes defensive bureaucrats, bullies, flat earthers, folks committed to a specific agenda and radio talk show hosts) may indicate that they’d like to have an argument, but they’re actually engaging in connection, noise, play acting or a chance to earn status. It can be fun to be in opposition, to harangue or even to use power to change someone’s position.
An argument, though, is an exchange of ideas that ought to surface insight and lead to a conclusion.
If you’re regularly having arguments with well-informed people of goodwill, you will probably ‘lose’ half of them–changing your mind based on what you’ve learned. If you’re not changing your mind, it’s likely you’re not actually having an argument (or you’re hanging out with the wrong people.) While it can be fun to change someone else’s position, it’s also a gift to learn enough to change ours.
The toddler puts on a show of having an argument, but they are holding a tantrum in reserve. If they ‘win’ the argument, no tantrum is needed. If they lose, they can tell themselves that they tried but the other person deserved the tantrum because they didn’t listen.
“Tell me about other strongly-held positions you’ve changed as the result of a discussion like this one…” is a direct way to start a conversation about the argument you’re proposing to have. “What sort of information would make it likely you could see this in a different way?”
It probably doesn’t pay to argue over things we have chosen to believe as part of our identity.