both forms of liberty are necessary in any free and civilised society. Negative liberty "liberty in the negative sense involves an answer to the question: 'What is the area within which the subject—a person or group of persons—is or should be left to do or be what he is able to do or be, without interference by other persons?'" For Berlin, negative liberty represents a different, and sometimes contradictory, understanding of the concept of liberty, which needs to be carefully examined. Its later proponents (such as Tocqueville, Constant, Montesquieu, John Locke, David Hume and John Stuart Mill, who accepted Chrysippus' understanding of self-determination) insisted that constraint and discipline were the antithesis of liberty and so were (and are) less prone to confusing liberty and constraint in the manner of rationalists and the philosophical harbingers of totalitarianism. This concept of negative liberty, Berlin argued, constitutes an alternative, and sometimes even opposed, concept to positive liberty, and one often closer to the intuitive modern usage of the word. Berlin considered negative liberty one of the distinguishing concepts of modern liberalism and observed "The fathers of liberalism—Mill and Constant—want more than this minimum: they demand a maximum degree of non-interference compatible with the minimum demands of social life. It seems unlikely that this extreme demand for liberty has ever been made by any but a small minority of highly civilized and self-conscious human beings." Suggestions that positive liberty is "abuse" in context Isaiah Berlin notes that historically positive liberty has proven particularly susceptible to rhetorical abuse; especially from the 18th century onwards, it has either been paternalistically re-drawn from the third-person, or conflated with the concept of negative liberty and thus disguised underlying value-conflicts. Berlin contended that under the influence of Plato, Aristotle, Jean-Jacques Rousseau, Immanuel Kant, and G. W. F. Hegel, modern political thinkers often conflated positive liberty with rational action, based upon a rational knowledge to which, it is argued, only a certain elite or social group has access. This rationalist conflation was open to political abuses, which encroached on negative liberty, when such interpretations of positive liberty were, in the nineteenth century, used to defend nationalism, paternalism, social engineering, historicism, and collective rational control over human destiny. Berlin argued that, following this line of thought, demands for freedom paradoxically could become demands for forms of collective control and discipline—those deemed necessary for the "self-mastery" or "self-determination" of nations, classes, democratic