It strikes me that I have only ever heard capable, wealthy people talk about the virtues of libertarianism. This does not invalidate the theory, but does call into question that value of their opinion. If you assume that there are "good" and "bad" outcomes for society, and we must pick an economic/social system which obtains the "best" outcome, then how do you choose it? You probably ask people what they think and what they themselves would prefer. In practice, no one really knows what the impact of most policies is on social welfare, so it is a difficult problem to test. So we tend to rely on the intuitive appeal of different ideas.
How much do you discount the opinion of someone recommending a policy that dramatically improves their own welfare? In most cases you discount the value of something someone says if it serves their own interests. However, if you have different people saying the same thing you are more likely to listen. The class of people recommending libertarian economics is very narrow. Mostly white, mostly male, mostly rich, mostly educated, mostly very capable of fending for themselves. Typically people who would do quite well in a tax-free, government-free utopia.
People recommending income equality and government intervention come from many different backgrounds. The majority of the poor. Many capable, wealthy individuals. Men and women. White and not. My question is do you put more weight on the opinions of 100 people from a diverse backgrounds (many of whom will be harmed by their recommendation) than the opinions of 100 people from the same background (all of whom will benefit from their recommendation)?
Let's say you set up an experiment. You ask people how much redistribution there should be. They can pick a number between 1 and 5 where 5 is complete income equality, and 1 is complete inequality. My intuition would be is that the people picking 1 and 2 would be far more homogeneous than the people up the other end. I suspect it would something like 95% high-income individuals.
Can you devise a weighting scheme that discounts votes based on the mean personal benefit of an option to the people choosing that option? Does mean personal benefit serve as a good proxy for the mean contribution of selfishness to a vote? Probably not, but maybe it is good enough to use. Of course, the wealthy would say the idea is foolish. It's a coincidence that the policies they support happen to benefit them personally. They don't support them because they are rich, but because they are clever. It's an unfortunate outcome that the correlation between cleverness the income makes them look self-seeking. If you could educate the poor, then they too would see the virtues of economic liberalism. Sadly, the poor are probably too stupid to ever understand. Perhaps we could develop a weighting system where high IQ led to higher weights. We could use income as a proxy for IQ. Or even the amount of land you own.
The poor are probably no less selfish than the rich, but the poor don't have the luxury of supporting ideals and policies that harm them. The many wealthy who support greater redistribution do have the luxury and they are the ones who bring down the mean personal benefit in the high redistribution categories.
I obviously support income redistribution. But that isn't evidence-based. I'm not completely sure that redistribution doesn't harm the poor. Sometimes I come up with ideas that would benefit me personally. I discount them a lot for that. Because I know how my mind works. Policies that are good and make my life better are far more appealing to me than policies which are good and make my life worse. Given that it's almost impossible to tell the difference between good and bad policies, I'm inclined to think that selfishness weighs in pretty heavily in most decisions. I doubt that this effect is much less for other people than it is for me. If I ever start recommending that we send old people to aged-care homes in Nauru for their own good, I hope someone will remind me that I've probably pulled the idea out of my arse.
This rant has all the hallmarks of the logical fallacy, except that I'm suggesting this in the absence of empirical arguments. If you're only data is the opinions of voters, then it might be reasonable to "attack the person". Committing the "fallacy" might result in better outcomes. If you're a benevolent alien dictator choosing between socialism and capitalism and your only data were people's preference and their incomes, you'd probably choose socialism.
All that can by summarised by the thought that there are capable and not so capable socialists but only capable capitalists. More importantly, I think that this is significant and not just interesting.