Lester examines the thorny issue of defining “liberty.”

J. C. Lester is a philosopher specializing in libertarianism. Apart from articles, dialogs, and book chapters—many available online—he is the author of Escape from Leviathan: Libertarianism without Justificationism (paperback 2012) and Arguments for Liberty (2011).

Any disvalued effect on other persons and their legitimate property that someone initiates (i.e., the effect is not a, proportional, reaction to something those others did first) can be said to be a ‘proactive imposition’ on those others. This expression enables us to explain and theorize social or interpersonal liberty as the ‘absence of proactive impositions’ (and so where clashes are unavoidable it is libertarian to minimize proactive impositions). It can be useful to view this formulation of liberty in two related ways: 1) the pure pre‐​propertarian, state of nature, interpretation, and 2) the rule‐​of‐​thumb propertarian interpretation.

1) Here ‘impositions’ are interpreted only as costs, meaning the opposite of benefits rather than opportunity costs. From applying this pure interpretation of liberty in a state‐​of‐​nature thought experiment, we can derive the existence of self‐​ownership itself, initial acquisition and private property generally, intellectual property, and contracts, and also resolve paradoxical or problem cases.

2) Here ‘impositions’ are interpreted as the flouting of self‐​ownership, private property and contracts, which therefore presupposes some such derivations as occur in 1, in order to deal with apparently clear property cases rather than start from first principles every time.

Libertarians usually have a good intuition of what is libertarian in practice and are very able to defend it. But without some explicit libertarian theory of liberty it is hard to do such things as give a clear account of what makes one thing liberty and another thing license, or to deal with novel or difficult cases in any principled way, or to answer even fairly simple philosophical questions or criticisms with any clarity or cogency. So the above theory appears to be an advance on merely assuming that self‐​ownership and private property are manifestly what constitutes liberty. And it leaves room for dispute, even among libertarians, about the nature and examples of being ‘proactive’ an ‘imposition’ and a ‘cost’.