 It is useful to think of the difference between the two concepts in terms of the difference between factors that are external and factors that are internal to the agent. While theorists of negative freedom are primarily interested in the degree to which individuals or groups suffer interference from external bodies, theorists of positive freedom are more attentive to the internal factors affecting the degree to which individuals or groups act autonomously. Given this difference, one might be tempted to think that a political philosopher should concentrate exclusively on negative freedom, a concern with positive freedom being more relevant to psychology or individual morality than to political and social institutions. This, however, would be premature, for among the most hotly debated issues in political philosophy are the following: Is the positive concept of freedom a political concept? Can individuals or groups achieve positive freedom through political action? Is it possible for the state to promote the positive freedom of citizens on their behalf? And if so, is it desirable for the state to do so? The classic texts in the history of western political thought are divided over how these questions should be answered: theorists in the classical liberal tradition, like Benjamin Constant, Wilhelm von Humboldt, Herbert Spencer, and J.S. Mill, are typically classed as answering ‘no’ and therefore as defending a negative concept of political freedom; theorists that are critical of this tradition, like Jean-Jacques Rousseau, G.W.F. Hegel, Karl Marx and T.H. Green, are typically classed as answering ‘yes’ and as defending a positive concept of political freedom.