Sir Isaiah Berlin was a political philosopher and a historian of ideas, one of the great intellectuals of the 20th century. His essay ‘Two Concepts of Liberty’ (1958) is a brilliant exploration of what freedom really means, personal and political.

The essay was groundbreaking because in the 1950s the dominant view was that socialism and communism had ‘liberated’ oppressed peoples. Isaiah Berlin, whose timber merchant father had fled Russia just after the Bolshevik Revolution, was under no such illusions.

Berlin wondered why leftist intellectuals in the United States and Britain hailed the new socialist states of the Soviet Union and in the East, while turning a blind eye to the decimation of personal freedom that were a part of those regimes.

“There has been no time in modern history when so large a number of human beings, in both the East and the West, have had their notions, and indeed their lives, so deeply altered, and in some cases violently upset, by fanatically held social and political doctrines.” Berlin

These doctrines purported to be raising people up to a greater level of freedom, but what sort of freedom was it in practice? There are two concepts or ways of understanding freedom and liberty, Berlin says.

Negative liberty is the extent to which we are free from interference or coercion by another person, group or government. Hobbes summed up negative liberty in Leviathan: “A free man is he that ... is not hindered to do what he has a will to.”

Positive liberty is the freedom to be something or someone. As Berlin puts it: “to be conscious of myself as a thinking, willing, active being, bearing responsibility for my choices and able to explain them by reference to my own ideas and purposes.”

Positive liberty seems very laudable, and indeed the end result is the ‘self-master’ ethic – becoming my ‘true’ or ‘higher’ self so that my potential is fully realized. Sounds good, right?

The problem is, there may be situations where I believe it’s justified to coerce others to do things that will lead to greater public health, or education, or justice.

The thinking goes: If people were slightly more enlightened, they would voluntarily take these actions anyway - so I’m just acting for their own good.