Prof. Zwolinski makes an interesting argument in favor of “marginal libertarianism” here.

I am sympathetic, but I think there is a better way to make the distinction, one that is both more accurate and more practically useful. This is destinationism vs. directionalism. My “directionalism” matches up with Matt’s “marginalism,” but it’s better. Marginalism means we are only trying for small changes. Directionalism means that we may have to settle for small changes, but large moves should be tried when we see a chance.

Here is I argued this point in my piece on Basic Income:

There are two main paths to deriving libertarian policy implications: destinationism and directionalism. The destinationist starts with two inviolable moral and ethical precepts that describe the ultimate libertarian destination, or ideal society: (a) Full self-ownership, with unrestricted rights to control and alienate both one’s own body and the products of one’s labor.

(b) An absolute bar on the initiation of force, even if such force would have net social benefits in consequentialist terms. The destinationist libertarian then uses these constraints as restrictions on the form and function of the state in the ideal, ultimate sense. No violations are tolerated. The directionalist asserts that any move that increases self-ownership, even marginally, and harms no one is an improvement and should be supported by the libertarian. This is true even if, from a destinationist perspective, the policy is not truly libertarian. One form of this approach is “weak Pareto”: Any policy that increases the liberty and welfare of one or more individuals, while making exactly zero individuals less free or less well off, is an improvement on the status quo. Any policy that increases the liberty and welfare of one or more individuals, while making exactly zero individuals less free or less well off, is an improvement on the status quo. If most people are indifferent, and a few are better off, moving from the status quo to a new policy is justified for the directionalist. The directionalist, if presented with several alternatives, would want to choose that alternative that enhances liberty and welfare the most. Destinationists identify ideal policies, using ideal theory. Directionalist libertarians identify a path that leads from the status quo toward ideal policies, using pragmatic and consequentialist considerations. For the destinationist, of course, anything other than the ideal outcome is an unacceptable compromise, because sanctioning a new but nonideal status quo implies complicity.

So, Matt and I agree on what not to do: The destinationist who requires full ideological purity or nothing lives in a world where policy irrelevance is a sign of virtue. I’ve had quite enough of that kind of virtue. The question is what to do instead. The notion of directional activism, with a final goal in mind and trying to make as large a move that way is possible, is easier to get people energized around. “Matt the Fabian Libertarian” would have us giving teas and being happy that one small town in Kansas privatized its garbage service. I think we can do more.