Jonathan Israel, A Revolution of the Mind (Princeton UP, 2010).

This book is based on lectures Israel gave at Oxford in 2008 in honor of Isaiah Berlin. The overall aim is to show how modern democracy emerged from the tension between Moderate Enlightenment and Radical Enlightenment.

The chief maxim of Radical Enlightenment is “that all men have the same basic needs, rights, and status irrespective of what they believe or what religious, economic, or ethnic group they belong to, and that consequently all ought to be treated alike, whether black or white, male or female, religious or nonreligious, and that all deserve to have their personal interests and aspirations equally respected by law and government” (viii). The four major founders of Radical Enlightenment were Descartes, Hobbes, Bayle, and especially Spinoza. The Moderate Enlightenment (featuring thinkers life Hume, Smith, and Voltaire) denies such thorough egalitarianism, conceding that a great many of us need to be ruled by others, though they do believe effective checks must be placed on these rulers (especially those who pretend to rule over religious doctrines).

Israel offers an provocative metaphysical difference between the Radicals and Moderates:

 Beyond a certain level there were and could be only two Enlightenments – moderate (two-substance) Enlightenment, on the one hand, postulating a balance between reason and tradition and broadly supporting the status quo, and, on the other, Radical (one-substance) Enlightenment conflating body and mind into one, reducing God and nature to the same thing, excluding all miracles and spirits separate from bodies, and invoking reason as the sole guide in human life, jettisoning tradition. (19)

The fundamental question is whether an ideal society can be based upon purely secular, monistic reason. Or must there also be a second substance presenting authority and tradition, whether through religion or the state – for the purpose of crowd control, at least? How much can reason do?

In my mind, Israel’s distinction between Radical monists and Moderate dualists parallels a distinction among historians regarding the role of ideas in explaining historical change. Though Israel is not Hegel, he clearly thinks philosophy is a significant contributor to social change – it lends “form and a sharp edge to a powerful emotional upsurge of deeply felt poetic and dramatic aversion to oppression” (88). Other historians think the head plays a much smaller role, and they turn instead toward less rational forces, such as those provided by economics, social structures, and historical accidents. Again: how much can reason do? According to Israel, it provides the central plot; according to others, it is more or less epiphenomenal. At issue in both distinctions is the relevance of ideas.