Arrow's Impossibility Theorem only applies in cases where ranked preference is the only information in the vote.
The "people", not being an individual or an AI or whatever, has a more complex preference vector than a ranked list. The real world is more complex than that.
So can we now agree that Arrow's Impossibility Theorem doesn't apply to all of democracy, that these things are nuanced and there is a long and deep conversation about this kind of topic that has been going on in the human race for centuries, and that frankly, pointing to technical flaws in established, stable enough systems that were set up by people with a hell of a lot less information about anything than us hundreds of years go is not going to do anything to prevent that system from operating in the way that it does or to convince people who have vested interests in it remaining stable?
Let's say I like party A 10 times more than I like party B. In a preferential voting system, there's no way to precisely express my preferences using the ticket. I'm forced to choose between "1. A" or "1. A, 2. B". Someone else who like part A 2 times more than party B will end up voting identically to me, despite the huge difference between our preferences. Any preferential voting system is necessarily flawed because how limited its input is.
That's basically what Arrow's impossibility theorem says. Due to its limited inputs, a preferential voting system will necessarily fail one of the three fairness criteria.
There are far better voting schemes out there, none of which are affected by Arrow's impossibility theorem.
What does it mean to like party A 10x more than party B? What I'm questioning here is the existence of cardinal preferences, which are necessary for a "will of the people" to be defined. The only way I can make sense of cardinal preferences is to treat them as dollars spent on private goods [1], but I doubt that's what the OP meant.
As it applies to this situation, it's moot - Portland did not express any cardinal preferences.
[1] Non-private goods introduce other incentives that prevent spending from tracking desire.
Let's say I value thing A ten times more than I value things B through K, and I value them all equally whether I get them together or apart because they apply to different spheres of my life. Then I would be indifferent between getting A or getting all of B-K.
Arrow's Impossibility Theorem says that ranked preferences are insufficient. One stronger assumption you can make is cardinal preferences, which is what desdiv appealed to.
The point is that invoking an impossibility theorem oftentimes - and also in this case - demonstrates that the formalization one has chosen to work with is not a desirable one.
For example, if a group of people by some social process comes to a consensus then arguably this represents the "will of the people". Thus it makes sense to reason about this concept without requiring the existence of ranked preferences.
What is an instance of "democracy in general" that you think Arrow's theorem doesn't apply to? It will apply any time "society" (i.e. more than one person) makes a choice among more than two options.
It won't apply if you can assign cardinal numbers to the options, but I doubt that's what you have in mind.
That's actually exactly what I had in mind. Range voting[0], for example, doesn't suffer from Arrow's impossibility theorem, Gibbard–Satterthwaite theorem, nor the Condorcet's paradox.
You know, I had a long comment here pointing out many problems with range voting. Instead, I'd like to observe that it really takes balls to defend range voting as "not suffering from the Gibbard-Satterthwaite theorem" when it's easy to show that range voting exhibits one of the failures that the Gibbard-Satterthwaite theorem guarantees in pure-ranking voting systems. Sure, the premises don't hold, but so what? If Gibbard-Satterthwaite did apply to range voting, that would guarantee no other problems than already occur.
Theorem: Hitting your thumb with a steel hammer, instead of hitting the nail, hurts like crazy!
Problem: The pain of a smashed thumb is bad.
Solution: Use an iron hammer. The requirements of the earlier theorem don't apply.
I don't know what "will of the people" means if not a ranked preference. Maybe you can explain?