The problem is that “verifiable fact” is actually very complicated in any context where you’re talking about politics. Two of the questions on the first graphic are about income mobility for people born in the bottom quantile. The graphic is correct, as far as it goes, but overlooks huge differences by race. While the average American born in the bottom 20% has a 7.8% chance of reaching the top 20%, that number is actually 25% for Asians.

Or, take the fact that the US lags Denmark in inter generational income mobility. Which is true, but it’s also true that the difference is due mainly to taxes and transfers flattening the whole distribution instead of fundamental structural differences that enable more movement: https://www.brookings.edu/blog/social-mobility-memos/2016/09.... Put differently, it’s not that the welfare system allows the son of a gardener to become an engineer, but that massive income redistribution reduces the disparity between gardeners and engineers. (For many Americans, that distinction could be dispositive in whether you support an expanded welfare system.)

So take these facts the next step. The authors studied these things in the context of support for reducing income inequality. Isn’t there a very plausible argument here that the experience of poor Asians shows that there isn’t a systemic structural problem keeping people in the bottom 20%? Or, isn’t it plausible that the generous welfare state doesn’t really fundamentally change people’s’ trajectories, but just reduces the divergence between those trajectories? And if you teach people the first set of statistics but not the second, are you educating them to make up their own minds, or feeding them facts to support a preconceived notion?

Stepping back: experts should certainly understand these facts. But what do we expect ordinary people to take away from them? Consider the work done by Piketty and Saez on income inequality: https://www.vox.com/policy-and-politics/2018/1/10/16850050/i.... Defining "income equality" actually is quite a quagmire. For example, in their 2003 work, P&S excluded the effect of tax transfers (such as the earned income tax credit) which significantly overstated the degree of inequality. Or, they mention that marginal tax rates were higher in the 1960s, but exclude the fact that the tax bases were narrower, such that the actual average tax rate on the top 1% hasn't changed dramatically over the decades: https://taxfoundation.org/taxes-on-the-rich-1950s-not-high. And there are so many other confounding variables to account for. The immigrant population today is almost triple what it was in 1960. Because immigrants often start at the bottom of the ladder, an increasing immigrant share could make incomes seem stagnant even though they’re growing within each different demographic. You also need to account for household sizes, major differences in marriage rates, etc. There are an enormous number of variables.

I'm not trying to take a side on this issue, I'm just using it as an example. These are issues of vast complexity. The facts are things experts can fight over. But do we really expect people to make political choices based on this information? Invocation of "facts" and "experts" have an intuitive appeal, but the "fact" is that for almost any disputed political issue, the facts are far from clear. So people use heuristics: ideologies, knee-jerk reactions, general principles, values. It's not clear to me that's wrong.