Here are the sort of political/economic thinkers whose substantive views I find most congenial: Friedrich Hayek, Milton Friedman, James M. Buchanan. If I tell most highly-educated people that these are the thinkers whose views of desirable institutions are most like mine, they might infer that I am some kind of rabid libertarian ideologue. But when I actually defend something like the arguments for an economic safety net each of these giants of libertarian thought actually set forth, lots of libertarians accuse me of not really being libertarian at all. And many liberals act surprised, as if I'm being saucily iconoclastic by wandering so far off the reservation. I can tell them that Hayek was actually in favor of a guaranteed minimum income and that Friedman basically invented the idea behind the EITC, but they'll still think I'm some kind of congenial squish. But what I am is a market liberal just like Hayek, Friedman, and Buchanan — the same intellectual role models who make me a rabid libertarian ideologue. So, which is it?
Frankly, “liberaltarianism” and “progressive fusionism” don't really amount to much beyond what Hayek, Friedman, and Buchanan thought anyway. So the fusionism here isn't really a fusion of anything. It's just seeing our way back to a pre-existing economically literate political liberalism.
Here's my conjecture about why this now looks more like an attractive position than it might have a few years back.
The 20th century libertarian-conservative alliance was based on anti-communism/socialism. The reasonable, sophisticated consequentialist pragmatism of the great 20th century market liberals seemed an insufficient bulwark against the slippery slope from the liberal, capitalist welfare state to full-on illiberal, totalitarian socialism. (Indeed, Hayek himself made the slippery slope argument powerfully, though unsoundly.) So there was a good deal of motivation for radical anti-socialists to coordinate around strongly categorical prohibitions against state coercion.
Misean economics, disinfected of the open-minded empirical consequentialism of Mises' Liberalism, and filtered through Ayn Rand and Murray Rothbard's peculiar views of rights and coercion delivers a powerfully moralized brief for capitalism that calls into question even taxation for the purpose of financing genuine public goods. That Rothbardians and Randians have wasted so much time fighting with each other on the question of the minimal state versus anarcho-capitalism obscures their unity on a rights-based bulwark against the slide from the welfare state to socialism. Sadly, “libertarianism” has become identified rather strongly with this ideology — an ideology some of the thinkers most strongly identified with libertarianism, like Hayek and Friedman, never shared.
The death of socialism as a viable competitor to the liberal-capitalist welfare state makes continued slippery-slope-to-socialism thinking look densely anachronistic. Other liberal welfare states, like the UK, Sweden, Denmark, Australia, New Zealand, etc., have moved in a rather more market-liberal direction, becoming rather less of a soft-socialist middle-ground between the American model and full-on economic socialism. The question these days is whether the U.S. will have the good sense to adopt more rational market-based old-age pension policies, like Sweden or Australia, or lower corporate tax rates to a level more in line with the rest of the wealthy world. Slightly higher personal tax rates and slightly more redistribution is a possibility, but a slide into socialism just isn't on the table. In this context, the negative income tax looks much less like a dangerous concession to the world-historical forces of evil.
Meanwhile, with the obsolescence of the anti-communist alliance with conservatives, many libertarians have sloughed off much of their previously tactically useful sympathy for socially conservative initiatives. Freed to be full-on social liberals, many libertarians are left sensing a much deeper cultural affinity for the left than the right. And this leads naturally to seeing more clearly their ideological affinities with welfare liberals. And then you read thinkers like Hayek, Friedman, and Buchanan, and you think: Oh, yes. This is extremely sensible. And now that the welfare-liberal elite has become rather more economically literate and is no longer sighing over five year plans, there is no reason to think they cannot find this sensible, too.
So that's where I'm at. An old-fashioned market liberal who thinks Hayek, Friedman, and Buchanan get it right, and who thinks Rawlsian welfare liberals should be able to recognize themselves in these thinkers.