[jfengel]

Decades is too much to ask, but one decade isn't. It isn't a single ideology, but a set of overlapping ideologies. Those do shift, as circumstances and priorities change, but generally not radically within the scale of a single Presidential term.

I'd say it's not unreasonable to commit to a party and re-evaluate that commitment every decade (or perhaps 8 years is a better figure in the US). That's not to say that you won't be constantly looking out for new information, like a technological change that makes you reconsider your ideas or the discovery that some candidate is very untrustworthy. But if you want anything nontrivial done, it's not going to happen on a time frame shorter than a half-decade -- and your allies are going to want to believe that you'll still be with them once they've achieved your top priority.

[pier25]

> I'd say it's not unreasonable to commit to a party and re-evaluate that commitment every decade

But that's a rational attitude and not what I was describing initially.

A lot of people commit to a party for all their voting life which generally is quite a few decades. Sometimes this even goes for generations.

[jfengel]

Oh, definitely. Parties change, and people's priorities change, and that gradually leads to a strain. Even purely rational people have a hard time telling when that strain has become a breach.

And a new alliance isn't easy to construct. You can't just go to the opposite party and say, "I've swung to you, so start catering to my priorities". Usually, you'll spend some time voting for nobody, in hopes that somebody will notice you, but that's hard without some level of organization, and that's work. In the meantime, you're failing to vote for a party that you had at least some sympathy for, and possibly losing to a party that has no reason to be on your side.

So a lot of people make party-line decisions based on inertia. They could improve their situation, but it's not as simple as changing their vote, since the existing alliances have priorities that won't change for a few votes. That leaves a lot of people in limbo, where there is no really great rational choice.