Isaiah Berlin (1909–97) distinguished between a ‘negative’ theory of liberty and a ‘positive’ one. Early or classical liberals have believed that freedom consists in each person being left alone, free from interference and able to act in whatever way they may choose. This conception of liberty is ‘negative’ in that it is based upon the absence of external restrictions or constraints upon the individual. Modern liberals, on the other hand, have been attracted to a more ‘positive’ conception of liberty, defined by Berlin as the ability to be one's own master, to be autonomous. Self-mastery requires that the individual is able to develop skills and talents, broaden his or her understanding, and gain fulfilment. For J. S. Mill, for example, liberty meant much more than simply being free from outside constraints: it involved the capacity of human beings to develop and ultimately achieve self-realization.
Gerçek yalnızlık başkalarından uzak yaşamak değildir. Gerçek yalnızlık, söylediğin şeylerin başkalarına uzak, anlamsız, anlaşılmaz gelmesidir. Isaiah Berlin