A post over at Libertarians Against War disputes that utilitarians can be libertarians:
This is why I think that anyone claiming to be ‘liberal’ or ‘libertarian’ should be grounded in natural law only.
As usual with natural law proponents, he doesn’t go into a coherent justification for natural law.
To put it bluntly, I have yet to hear any kind of coherent argument for natural rights that doesn't simply fall back on utility in some way, shape, or form, or attempt to slide it in through the back door. Let’s look at some of Rothbard’s arguments for natural rights.
The natural law, then, elucidates what is best for man — what ends man should pursue that are most harmonious with, and best tend to fulfill, his nature. In a significant sense, then, natural law provides man with a "science of happiness," with the paths which will lead to his real happiness.
To further explain natural law, he quotes Sir William Blackstone:
This is the foundation of what we call ethics, or natural law … demonstrating that this or that action tends to man's real happiness, and therefore very justly concluding that the performance of it is a part of the law of nature; or, on the other hand, that this or that action is destruction of man's real happiness, and therefore that the law of nature forbids it.
Hmm…sounds pretty utilitarian-ish to me, but maybe it’s the shrooms kicking in.
Rothbard tries to deny that he’s sneaking utility through the back door, but fails.
In contrast [to natural law] praxeology or economics as well as the utilitarian philosophy with which this science has been closely allied, treat "happiness" in the purely formal sense as the fulfillment of those ends which people happen — for whatever reason — to place high on their scales of value. Satisfaction of those ends yields to man his "utility" or "satisfaction" or "happiness." Value in the sense of valuation or utility is purely subjective, and decided by each individual. This procedure is perfectly proper for the formal science of praxeology, or economic theory, but not necessarily elsewhere. For in natural-law ethics, ends are demonstrated to be good or bad for man in varying degrees; value here is objective — determined by the natural law of man's being, and here "happiness" for man is considered in the commonsensical, contentual [is this even a word? –Cork] sense.
There you have it, folks. Yes, natural law is still based on utility, but it’s different, y’see, because the happiness it promotes is more “commonsensical” (seriously, this sounds like Boomhauer from King of the Hill). Y’see?
First off, Rothbard seems unfamiliar with the various branches of utilitarianism (what he’s describing here is preference utilitarianism, and what he’s describing in other essays is generally a bastardized form of act utilitarianism). But I digress. While this section is so vague that it barely makes sense, Rothbard seems to be saying that he’s only promoting utility in a “general” sense—in the sense that’s based around man’s natural being. But isn’t any theory of utility for man going to have to acknowledge man’s nature in one way or another?
Now, a thousand people are going to show up in the comments section to kick my ass (god bless 'em). For all I know, maybe they’ll succeed. I don’t claim to be any sort of expert philosopher, and I know there are many natural-rights proponents out there who are extremely intelligent. But still…if were to purge all those who use utility-based rationales for libertarianism, the natural-rights proponents would be purged as well, no?