Oddly, I thought this discussion would be about actual toddlers.

There is a way to win an argument with a toddler. You find out what's bothering them, usually something emotional, and you validate it. "Yes! It's fun to stay up late! Yes! You don't want to eat your vegetables!" Once they feel heard, you've got a shot at getting them to do what you want.

That's a good way to win an argument with a non-toddler as well. Acknowledge that what they want is legitimate (if it is). Concede points of agreement. Talk about shared goals. Only then talk about a different path to the solution.

Nobody ever changes their opinion on things with anything remotely like a high degree of frequency, and that's not a particularly bad thing. The "real" point of an argument is not to persuade the other side (though that is what you aspire to nonetheless) but to exchange views, and often to indirectly explore your own views more deeply, at least in the scenario where your 'partner' can bring up something you weren't aware of.

Our views actually shifting is something that only happens over many years and often for reasons we aren't really in control of. Me of 10 years ago would vehemently disagree with me of today on many things, and there's probably pretty much no argument I could have engaged with him to persuade him of what I obviously think are 'more correct' views. It required, most of all, life experience that isn't going to be able to be communicated with words. If it were we'd all have the wisdom of a man who'd lived for millennia. And if not all of us, then at least somebody - but that somebody doesn't exist.

One who wants to debate while rejecting the real state of mankind is oft going to just find themselves in an echo chamber.

One of the surprising benefits of raising a toddler is gaining the ability to instantly tell when another adult has fallen into a "toddler-like" state (myself included!).

Before having kids, I would try and explain someone's behavior in a logical sense.

Toddlers, however, are mostly driven by their current physical needs (hungry/sleepy) and whatever they're currently doing (autonomy).

We've found the most success in avoiding all boolean questions. Do you want to read a book? (when playing with trains before bedtime) Obvious no!

Do you want to read this book or that book? Oh... a decision!

It's striking how well tactics like these work outside the realm of toddlers.

One thing that helps is to be charitable.

Ideas in general are difficult to express and people struggle with conveying them separately from their private ideas, personal experiences, and personal reasons for believing what they believe.

If you want to be a good interlocutor, you have to deeply absorb what the other person is thinking and sometimes even help them develop their understanding with the hope that others can do the same for you. We are all toddlers at times.

Before asking "How to win an argument with a toddler?", first ask:

  1- "Might the toddler be right?" 
  2- "Am I the toddler in this interaction?"