‘Peter Kropotkin is without doubt one of those who have contributed perhaps most – perhaps even more than Bakunin or Elisée Reclus – to the elaboration and propagation of anarchist ideas.’ So wrote his contemporary, Malatesta, Italy's most famous militant and theorist of the time, who, if always a friend and comrade of Kropotkin, was also one of his sharpest critics.

A prominent revolutionary agitator as well as distinguished geographer, Kropotkin had a remarkable capacity for communicating easily with both the educated bourgeoisie and the oppressed classes. If he lacked the dramatic presence of Michael Bakunin and the oratorical brilliance of such figures as Sebastien Faure and Louise Michel, there was nevertheless a compelling persuasiveness in his writing which few could match. This persuasiveness sprang partly from his passionate and uncompromising concern for social justice but it was also due in no small part to the way he linked the development of anarchism to the development of science.

Kropotkin shared the optimism of the positivists in the limitless possibilities of the inductive deductive methods of scientific enquiry. In so doing he perhaps went further than Proudhon or even Reclus in rejecting as unscientific all metaphysics and the justification they gave to the power of church and state, whether emanating from the Christian belief in an all-powerful god or from the hegelian concept of the universal spirit. In 1913 he went so far as to write a particularly savage attack on Bergson, the French philosopher, for denigrating science by arguing that intuition played an important part in scientific discovery. Certainly he recognised the difficulties of attaining the same level of exactitude in sociological studies as in physics and chemistry.