> Or even if they did, the amount of effort they'd put in...
This is actually quite an interesting area if you look into the game theory of making choices in a group setting. Strong strategies typically often don't involve doing much research, but they are rather frustrating for the people who take an interest in politics. Real-world behaviours are arguably quite reasonable on this front too, although they are limited by the ability of the average person to reason their way through the policy suggestions being made by though leaders.
Although I do agree that more voters isn't better. There is a certain level of objective correctness in political decisions if we admit basic ideas like "policies should be tested to see whether they achieve the goals that they were intended to" as a measure of success and the point should be to design systems that optimise on it to some degree.
Yes. And in detail, with this model of a rational electorate, skilled influencers put the effort in to devise a policy platform and convince others that it is good for them. The majority pick a platform that they are convinced by.
It's worth it for the influencers, because they have an outsized impact. It's worth it for everyone else only if choosing a coalition is very low-effort. Or if they are entertained by the influencers.
Again, I'm an ardent democrat. I'm just pointing out the flaws in any argument that assumes rational voters are a good thing - because it's rational to not waste much time on voting. Instead, democracy works best when voters feel an arguably irrational sense of duty and civic pride.
But that wouldn't be rational. The rational approach is to vote when you are in (or plausibly in, or plausibly going to eventually be in) the majority coalition. The hyper-rational equilibrium is politicians do exactly what a majority coalition of voters want and no-one bothers to vote, but once the politicians start becoming flawed or preferences change over time the equilibrium shifts quite rapidly to a rational voter base forming large coalitions that turn up to vote.
It isn't rational to vote if for people who aren't affiliated with a coalition to some degree (and never will be) but people like that are basically a political non-factor anyway and are probably legitimately wasting their time when they vote because there is no policy formula available that they want to support, by definition.
A rational anaylsis would therefore conclude I'm wasting my time and energy even just walking to the polling station, let alone keeping up with political developments through the intervening months and years. As you say, in a hyper-rational world turnout would be way lower - whether it would oscillate and overcorrect as you suggest, or reach a stable equilibrium, I'm not sure.
But whatever my motivation for voting and trying to stay informed, I do not believe it is primarily rational. It's probably some mixture of duty, diversionary entertainment, and ritual. If lowering the voting age to 16 could help inculcate that sense of duty and better establish that ritual, that would be a pretty convincing reason to do it in my opinion.
No it wouldn't. You haven't established the link between your premise and conclusions and the rational view is the opposite of what you came to. You've established that in the best case the candidate you prefer will win by more than one vote - which is correct but not the end of the line of thought.
Think of it like building an embankment. If you design the embankment to exactly hold back the maximum amount of water you expect it to hold it'll probably fail in an emergency when it shouldn't have because something slightly unexpected happens. The rational thing to do is engineer in a margin of safety. You're trying to optimise the wrong metric which is ~30-60 minutes of a voters time vs. probability of the legislature behaving in a way that is favourable to them. In both voting and embankment building it'd be silly (dare I say, irrational) to aim for a narrow success. The median election (analogy: median storm) should make the margins for your candidate (analogy: embankment tolerance) look excessive (analogy: over-engineered).
Otherwise, you're basically arguing that rational people should optimise their way to being on the losing side of elections - which is a big tip-off you're making a logic error in your argument somewhere. Rational behaviour can't, almost by definition, predictably lead to bad outcomes.
Or even if they did, the amount of effort they'd put in researching, considering and modelling the potential outcomes would would be commensurate to the impact they would expect their vote to have. I suspect for a good chunk of adult voters, this is in fact the case.
So it's not obvious to me that including more voters whose decision-making is more emotional will necessarily produce worse outcomes. It's conceivable it'll produce better outcomes.
Edit: I'm being downvoted. To be clear, I'm an ardent democrat, but the idea that people vote analytically and rationally doesn't make sense for the above reason. The most informed voters are, in my experience, often highly emotional.