If the extraordinary range of Ernest Gellner's writings over the last two decades makes it clear that his intellectual project is nothing less than that of characterising the spirit of modernity, his most striking statement about the principles of social organisation suited to the modern era remains that offered in Thought and Change. Legitimacy in the modern world, he asserted, does depend and ought to depend upon obeisance to two, and only two, principles: nationalism and industrialism. On reflection, the latter of these two principles should be considered the more important for Gellner, given his insistence on explaining nationalism as a corollary of industrialism – or, more precisely, as an unintended consequence of the uneven diffusion of industrialism around the globe. Although a consideration of the prospects of peace requires some consideration of nationalism, the privileged position Gellner lends to industrialism in his thought is taken as justification for a similar concentration in this essay. My intention here is to flesh out one aspect of the industrial society thesis, namely its attitude towards geopolitical conflict. In summary terms, the industrial society theorists expected that their new world would bring peace. Gellner puts the matter like this: