Titans who bestowed gift of light

Simon Blackburn marvels at the roll-call of thinkers who led Europe out of the dark

Which thinker was principally responsible for replacing the thrones and altars of early modern Europe with the liberal democracies that followed? Hobbes? Locke? Descartes? Newton? Voltaire? Rousseau? Or does the question make no sense? Jonathan Israel holds that it does make sense and has a different answer: the Portuguese-Dutch philosopher Baruch Spinoza.

Israel revealed this answer in his magisterial and highly praised book Radical Enlightenment: Philosophy and the Making of Modernity 1650-1750 , which was published in 2001. Anyone not looking closely at the subtitles might have expected the current volume to continue the story of the first.

But while its thousand or so pages sacrifice 20 early years, they compensate with only two later years, for this book is designed to amplify the story told in its predecessor, both in the sense of adding new material and of repeating the message at a higher volume.

The message is forthright, and its banner headline should be welcome to philosophers and writers. Israel holds that ideas matter. The 18th and 19th-century historians who praised or blamed l'esprit philosophique for European and American revolutions were right, and attempts to put these changes down entirely to non-intellectual social and economic forces were misguided. Furthermore, the world of ideas has its own Napoleons, and this brings us to the crowned and anointed hero of both books, Spinoza, flanked by Pierre Bayle, and followed by a host of mainly French esprits forts , especially La Mettrie and Diderot. They are the people who made modernity. They comprise the "Radical Enlightenment": atheist, materialist, subversive, rationalistic, emancipatory, egalitarian, democratic and destined to be revolutionary. In the wings, mere bit players, are the English and the Scots. Neither country managed to produce real radicals, at least after Hobbes, and apart from a few minor visitors to Spinoza's tent, such as Collins and Toland. Locke and Newton, and even Hume and Smith, simply lacked the bottle. They were believers or, at best, agnostic rather than atheist. They were not particularly subversive or were even lackeys of the state, half-heartedly democratic, scarcely egalitarian, seldom heard to blow the trumpets of emancipation and, in the end, unimportant to the progress of history.

Israel's case is brilliantly presented and dense with learning (there are by my count 25 closely packed pages listing primary sources, and 56 listing secondary sources in this book; in its predecessor the numbers were 21 and 30 respectively). Few scholars could assemble such a roll-call of witnesses, from such a cluster of European countries. In the depths of a forest such as this critical voices become muffled. Yet perhaps there are some things that invite queries, at least to the philosopher's ear.

Consider the efficacy of the philosopher. Israel rightly dismisses the foolish view that, since the bulk of the people cannot understand philosophical writings, the ideas crafted in those writings cannot work on the popular mind and issue in popular movements. They can and do, and, if ever there was a period that illustrates Nietzsche's saying that a philosopher is an explosion waiting to happen, it must have been the beginning of the long 18th century. But there remains a question whether the impact of ideas comes about through a history of sayings, of new arguments newly won, or rather a history of receivings. Atheism, or scepticism, and materialism have long been said; what seems to have happened at the end of the 17th century is not so much that they were said again, or said better, even by Spinoza, but that they began to be heard and feared when in the preceding centuries they had been met with silence. The question of why that change in mentalites happened is not obviously internal to intellectual history but may well be a consequence of external social, political and economic forces. For comparison, radical Islamists need only to read again some very old words (it might be blasphemous to read any others), but what is distinctive of today is that those words become heard in a particular way and acted upon by vast numbers of people, when at other times they were not.

Another query may arise because Israel tends to label writers as "radical"

or "moderate" without qualification, as if context will automatically supply the dimension within which they are one thing or the other. But the problem is that a writer can be radical or not in different dimensions. A philosopher can be radical in the good sense of getting further down to the roots, uncovering hidden presuppositions and querying hitherto invisible dogmas, yet emerge with no earth-shaking practical or political platforms.

We should surely not assimilate the intellectually radical to the politically extreme. A firebrand inferring that since God does not exist we should have plebiscites on all political decisions is perhaps politically radical but philosophically extremely naive.

Israel mostly writes as if there are two unquestionable signs of the radical in the period in question: materialism (or monism), holding that there is but one kind of substance, and atheism. But what was shocking about the pantheist Spinoza was not his difficult view about substance, nor simple atheism, but his doctrine of necessity and the denial of providence.

If materialism and atheism are the touchstones, no wonder poor Hume gets shouldered out, because in the one case he attacked the notion of substance needed to make sense of the issue of materialism, while in the other case he held that philosophically the distinction between atheism and theism is merely verbal because the existence of a designer or creator affords no premise for any inference to conclusions about this life, a future life or our moral and practical lives - a lesson radical enough to still need learning by soi-disant theists and atheists alike. One might indeed try saying that this same attitude was prefigured by Spinoza, but Israel does not go that way, and in any case this is just a tiny sample of Hume's encompassing philosophical radicalism.

Why does the history matter, to us, here, now? With characteristic insight, the late Bernard Williams made a distinction between the history of philosophy and the history of ideas. The former looks at great dead philosophers with an ear attuned to what they have to tell us, here and now; the latter looks at the contemporary matrix within which its subjects wrote and potentially highlights social and historical circumstances that have little or no echoes in the modern world. The two enterprises are not utterly distinct but, Williams thought, it is not possible simply to combine the virtues of both, any more than it is possible to have the Impressionist concentration on the surface effects of light and at the same time a delineation of mass and structure as forceful as those that can be achieved by other means.

The vice of history of philosophy, especially according to historians of ideas, is anachronism. And the vice of history of ideas is antiquarianism.

The one problem is that of failing to stay sensitive to proper historical distance, and the other is that of failing to see the philosophical forest for the social, political, religious, economic, literary and other trees.

Among other things, the two enterprises are bound to differ in scale. A philosopher interested in, let us say, Descartes's view of the self must immerse himself in relatively few texts, but then puzzle hard over whether such remnants of his thought as have survived to haunt us deserve to have done so. This could be a fairly self-contained enterprise and might be satisfactorily wrapped up in a journal article or, at best, a short monograph. The historian of ideas approaching the same topic will face material about the Christian tradition and its internecine debates, about the rise of individualism, the relation between subjectivity and modernism, contemporary concepts of scientific explanation and much more besides. A short article or monograph, or even a substantial one, could be no more than an indicator or taster of something more adequate, and the very idea of a complete story or last word will rapidly seem fantastical - presumably this is why Israel has gone over his vast arsenal of materials this second time.

The book ends with a spirited defence of the value of the Enlightenment.

The ideals of equality, democracy, freedom, toleration and reason deserve our allegiance. Their arrival in the 18th century was not the substitution of one set of gangsters for another, nor is their claim "totalitarian" or "hegemonic" in the way proclaimed by the Frankfurt School or by postmodernism in general. Kant was right: the Enlightenment was the period when we escaped from the long period of human tutelage or better, say, when some of us did, perhaps only for a time. Night still has its apologists.

Daylight cannot be taken for granted, and this astonishing panorama of its dawning should help anyone to realise why not.

Simon Blackburn is professor of philosophy, Cambridge University.