Jason Brennan opens the second chapter of Libertarianism: What Everyone Needs to Know with the question: How do libertarians define “liberty”? He answers his question by distinguishing between “two major kinds of liberty: negative liberty and positive liberty.” Negative liberty, Brennan explains, signifies “an absence of obstacles, impediments, or constraints.” Positive liberty, in contrast,

is the power or capacity to do as one chooses. For instance, when we talk about being “free” as a bird, we mean that the bird has the power or ability to fly. We do not mean that people rarely interfere with birds.

Negative liberty is the absence of obstacles; positive liberty is the presence of powers or abilities.

Brennan’s bird does not serve his purpose; it is a poor example. When we speak of being “free as a bird,” we don’t usually mean what Brennan claims we mean. To be “free as a bird” suggests more than the power or ability to fly. It also suggests that the exercise of that ability is not hindered by external constraints. The fantasy of being “free as a bird” is linked to the desire to be free from external constraints—or, as Brennan puts it in his account of negative liberty, to act in “the absence of obstacles.”

The connection between the ability to fly and negative freedom is expressed in these famous lyrics from “The Prisoner’s Song”:

Now, if I had the wings of an angel,
Over these prison walls I would fly.

When we speak of a bird as being “free” to fly, we assume that the bird in question has not been confined in a cage. We would not normally speak, for example, of a caged canary as being free to fly. This way of speaking suggests that a bird can exercise its ability to fly without external constraints, such as by being locked in a cage. The notion of negative freedom is, at the very least, an implicit presupposition of all such examples.

Of course, a caged bird may be free to fly around inside his cage to some extent, just as a human prisoner in solitary confinement may be free to walk within the confines of his tiny cell. Such cases illustrate the fact that negative freedom, or liberty (the terms are normally used interchangeably), may exist in varying degrees. But to say that a prisoner possesses the “positive freedom” to walk merely because he possesses the power or ability to walk (as Brennan’s bird is said to be “free” to fly in virtue of its ability to fly) is to use the word “freedom” in a peculiar way.

According to the positive conception of freedom (as summarized by Brennan), the fact of imprisonment would not even diminish a prisoner’s “freedom” to walk, so long as he remains able to walk. Even a prisoner bound tightly in chains would still be free to walk in the positive sense, provided he retained the ability to walk. When we say that a chained prisoner is not free to walk, we mean that he is constrained and therefore lacks the negative freedom to walk as he chooses, not that he lacks the power or ability to walk per se.

I may seem to be nitpicking here, and so I might be if not for Brennan’s attempt to incorporate positive liberty into libertarian theory. As he puts it (p. 27):

Until recently, most libertarians tended to argue that the only real kind of liberty is negative liberty. The believed the concept of positive liberty was confused. For a long time, the status quo was that libertarians and classical liberals advocated a negative conception of liberty, while left-liberals, socialists, and Marxists advocated a positive conception of liberty.

Brennan assures us that the status quo has begun to change: “Recently, though, many libertarians have begun to accept both negative and positive liberty.”

When contemporary libertarians say they want a free society, they mean that they want both (1) a society in which people do not interfere with each other and (2) a society in which most people have the means and ability to achieve their goals.

I confess to being unclear about the identity of the “many libertarians” who embrace positive liberty; but judging by Brennan’s subsequent mention of a book he co-authored with David Schmidtz, he appears to mean “neoclassical liberals.” In his recommended readings at the end of his book, Brennan lists four authors (including himself) under the heading “Neoclassical Liberalism.”

Now, there are probably a few more neoclassical liberals roaming the halls of academe, and I won’t quibble over how many libertarians it takes to qualify as “many libertarians.” But when Brennan moves from “many libertarians” to his much broader statement about what “contemporary libertarians” supposedly believe about positive liberty, I must question his sense of proportion.

Consider Brennan’s next statement: “Until recently, most libertarians rejected the concept of positive liberty.” Until recently? Admittedly, I am not as active in the libertarian movement as I once was, but I doubt if I missed a sea change in regard to what “most libertarians” (including conventional classical liberals) think about the notion of positive liberty.

Brennan is again exaggerating the influence of his band of neoclassical liberals. A handful of academic philosophers does not a movement make.

Let’s proceed to the more substantive problems in Brennan’s account. Why was the notion of positive liberty traditionally rejected by libertarians? According to Brennan, libertarians “thought that if positive liberty—understood as the power to achieve one’s ends—counted as a form of liberty, this would automatically license socialism and a heavy welfare state. Since they opposed socialism and a heavy welfare state, they rejected the concept of positive liberty.”

This explanation is neither accurate nor fair; traditional libertarian objections to positive liberty were far more sophisticated than Brennan would have us believe. I will cover some of those objections in my next essay. For now, we should try to understand what the point of all this is. Why, for instance, do we find Brennan (p. 28) asking this loaded question: Why do many libertarians now accept positive liberty? Brennan explains:

Contemporary libertarians tend to embrace positive liberty. They agree that the power to achieve one’s goals really is a form of liberty. They agree with Marxists and socialists that this form of liberty is valuable, and that negative liberty without positive liberty is often of little value.

Permit me to be blunt: contemporary libertarians, on the whole, “tend to embrace” no such thing. They do not agree with Marxists and socialists on this matter. On the contrary, they tend to argue that positive liberty is not a “form” of liberty at all, if by “form” we mean to suggest that positive and negative liberty are two species of the same genus. Rather, as Murray Rothbard wrote in Power and Market (p. 221), freedom pertains to “interference by other persons.” The word, in a social context, “refers to absence of molestation by other persons; it is purely an interpersonal problem.”

I see no evidence to indicate that the mainstream of libertarian thinking has changed substantially from this description of “liberty” given in 1773 by the American clergyman Simeon Howard:

Though this word [liberty] is used in various senses, I mean by it here, only that liberty which is opposed to external force and constraint and to such force and constraint only, as we may suffer from men. Under the term liberty, taken in this sense, may naturally be comprehended all those advantages which are liable to be destroyed by the art or power of men; everything that is opposed to temporal slavery.

According to this approach, negative liberty (the absence of coercive interference by others) is itself the fundamental means by which individuals are enabled to pursue their own values as they see fit. Brennan doesn’t disagree with this assertion, as we see in his remark (p. 29) that “protecting negative liberties is the most important and effective way of promoting positive liberty.”

Thus, a commitment to positive liberty does not license socialism; it forbids it. Marxists say that positive liberty is the only real liberty. This real liberty is found in market societies, and almost nowhere else.

Brennan obviously wishes to turn the notion of positive liberty against socialists and other advocates of expansive governmental powers; whether his efforts are successful is a problem I shall take up at a later time. For now I wish only to point out that everything Brennan wants to say could easily be said without dragging in the notion of positive liberty at all. What we have here, in my judgment, is a type of political correctness run amok.

Will socialists, seduced by Brennan’s endorsement of positive liberty, see the light and agree that free markets are the best means to attain their cherished goal of positive liberty for everyone? As the old saying goes, there are two chances of this happening: fat and slim. By needlessly incorporating positive liberty into libertarian theory and, even worse, by claiming that negative liberty without positive liberty often has no value, Brennan has opened the barn door so wide as to admit all manner of anti-libertarian proposals.

Brennan appeals to “historical fact” to support his claim that free markets are the best way to achieve positive liberty. He would have gotten no objection from me if he had simply said, as Murray Rothbard put it in Power and Market (pp. 221-22), that “it is precisely voluntary exchange and free capitalism that have led to an enormous improvement in living standards. Capitalist production is the only method by which poverty can be wiped out.” But this straightforward claim wasn’t good enough for Brennan, who succumbed to the desire to put old wine in a new libertarian bottle labeled “positive liberty.”

In short, Brennan’s attempt to incorporate positive liberty into libertarian theory accomplishes nothing more than to transform a strong argument for free markets into an argument that is perilously weak.

Anyone concerned with “historical fact” needs to understand why the notion of positive liberty proved so destructive to the negative liberty defended by classical liberals and libertarians. This will be the subject of my next essay.