In the areas where we disagree, each of us departs from stock libertarianism in one case - and not in the other. I think it's worth looking at where each of us emphasise principle over practicality - and vice versa.
I'm an exception to all other Libs I know of in that I advocate a strong and secure social safety net. I don't refer to it as "socialism" or "welfare stateism" in that I am not talking about those approaches to this particular problem. However the lack of success in a particular approach toward solving a problem does not make the problem go away. Generally it makes it worse. In the case of both socalism and welfare state policies, centralized planning and paternalism make the problems addressed so very much worse that it's easy to believe that merely getting rid of the solution would solve the problem.
Oh, if only it were that easy. But in fact, it's not, and a comparison of the livability and costs to citizens in the "socialized" nations of europe shows that recognizing and dealing with poverty least intrusively dealt with by a very simple process: Give the poor enough money to not be poor AND desperate.
Poverty is relative - desparately poor is to put people under basic survival pressure. When enough people in your society ARE under survival pressure, Very Bad Things Happen that in our nation, You See On Fox Every Day.
I differ from Ron in having had the opportunity of being poor in Canada - and now seeing what being Poor in America is like. Hell, in many ways it's better to be poor in Canada than Lower Middle Class in America. At least you have health insurance!
So we differ there, in that I feel that it's a government's duty to address matters of common concern to all citizens; healthcare, poverty and crime are all issues that are common concerns and which tend to be causes and effects of each other.
On the other hand, we disagree passionately on the issue of open vs closed borders. As a Libertarian, I believe in the free movement of peaceful people. Furthermore, I feel that this whole matter falls under the Bobatearian principle of "no Stupid Laws," that is to say, laws that are intrusive by definition and which will obviously increase both hassle and provide endless opportunities for the corruption of government officials.
I like what another Libertarian running for President has to say on this topic.
I attribute most anti-immigrant sentiment to race panic, where people see the culture changing in response to new waves of immigrants and proceed to freak out in all directions. As the decendent of economic migrants myself, like most people who are not actually Native Americans, I find arguing against open borders both unprincipled as a libertarian and distasteful as a civilized human being. But perhaps Ron cannot risk alienating the racist right together with the racist left and racist center. Very well.
Beyond the economic and cultural positives of open immigration, we must consider the national defense problems posed by "closed" immigration.
Capital -- including human capital -- moves to where it can be most profitably invested for all concerned, and it rolls right over government barriers to do so. In practice, this means that millions of immigrants arrive, and will continue to arrive, in the United States each year regardless of what our government does to stop them.
Right now, nonsensical US immigration policy forces many of those immigrants to sneak in rather than walk in "through the front door." Reasonable estimates put the number of illegal immigrants from Mexico alone in excess of one million annually. An entire industry of cross-border guides, called "coyotes," is built around getting those immigrants into the US to live and work. These "coyotes" don't care one way or another whether the person they're smuggling into the US is a janitor from Guadalajara or an al Qaeda fighter carrying the material to make a "dirty bomb" in Dallas. And our immigration policy gives the latter type of "immigrant" a huge crowd to hide himself in.
The first step in providing for our national defense at the border is to let those who bear us no ill will to come in "through the front door" -- to walk across the border publicly and conveniently instead of sneaking over it in the middle of the night and in the middle of the desert. Believe me, they'd rather be welcomed than hunted ... and welcoming them rather than hunting them will reduce the cover they provide for our enemies.
The second step in providing for our national defense at the border is to re-focus the government services which address that border away from hassling peaceful immigrants and toward detecting and eliminating real threats to the United States.
But I have no such excuse and I won't provide him cover on this issue.
There's a far simpler way of dealing with the poverty that drives people to climb the border fences and risk death in the desert, and that is to adjust our foreign and economic policies that are, frankly, aimed at keeping our southern neighbors broke, for the sake of cheap bananas and minerals. Free and fair trade will do more to stem the flood than any tonnage of barbed wire and guard dogs.
Oh, and a fence that keeps other people out is pretty damn good at keeping you IN, come the day Bush decides to round up the Usual Suspects.