Machan points out that “natural law” can be deduced logically from considerations of human nature, and I agree with that. He accuses Duncan of failing to prove the apparently arbitrary notions he is putting forward in this book.
Duncan replies as follows:
There is at least as much diversity of opinion within the natural rights / natural law tradition as there is in the tradition of egalitarian liberalism in which I work. Aristotle, Cicero, Aquinas, Locke, and all the rest of the thinkers associated with this tradition hardly speak with one voice.
Indeed, Machan himself recognizes the diversity of practices that were once thought “natural” but no longer are. I do not know why he thinks this diversity is a problem for my theory but not his… (145-6)
The reason why it’s not a problem for natural law libertarianism is that the diversity of views is due to the many thinkers’ objective failure to get it right. If we are smarter than they and study hard, then perhaps we might be able to expose their errors and substitute more correct opinions logically. On the other hand, I have seen no attempt at a proof by Duncan of his own philosophy. Why should we heed his intuitions?
Machan clearly grasps that the free market is not to blame for failures of interventionism: “Some of the concerns about free markets have to do with the historical fact that the system has always been in force as a mere shadow of its theoretical self, incorporating various elements of feudalism, mercantilism, the welfare state, and other systems that arguably generated the problems — for example, the Great Depression, which can be traced to monetary policies of the federal government.” (138)
He addresses the slander that, as the respondents’ emails to Steven Landsburg also allege, “economists [and libertarians] are nothing but shills for special interests” (Big Questions, 54): “By no means, then, is the libertarian lobbying for any special privileges for business, any more than for art, science, education, athletics, entertainment, or any other group of citizens with specific goals they wish to pursue.” (139)
Finally, there is Machan’s understanding of the role of democracy and positive law in a libertarian society. Regarding the executive branch of the government, “political and legal administrators who carry out the task of rights protection” may well be elected. Regarding the legislature, the main task of the lawmakers is to “extend the principles of a free society to new areas of concern, such as how property rights or rights to free expression apply to, say, radio, television, computer programs, space, and the Internet.” (133)
My own view is that the judiciary in a free society ought to be entirely private, and the “part-time” legislature ought to concern itself with empirical matters, such as continuums (what is to be the exact customary age of consent for sex?), local externalities like nuisance laws, and empirical issues like exact punishments for crimes.