Book review: The Enlightenment, and why it still matters, By Anthony Pagden

"If I knew something useful to my family and not to my country, I would try to forget it," the French Enlightenment philosopher Montesquieu argued. "If I knew something useful to my country and harmful to Mankind, I would look upon it as a crime."

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Montesquieu's sentiment expresses, for Anthony Pagden, the essence of the Enlightenment. In the belief that all humans "share a common identity and thus belong ultimately to a single global community – a cosmopolis" lies, he suggests, the Enlightenment's greatest legacy. Unlike, say, the Renaissance or the Reformation, the Enlightenment is not simply a historical moment but one through which debates about the contemporary world are played out. Pagden, too, writes with one eye to current discussions about, and attacks on, cosmopolitanism. He pursues an important argument here. The Enlightenment, he suggests, developed through a struggle with the ghosts of two Thomases: Aquinas and Hobbes.

It was Thomas Aquinas who had, in the 12th century, created a new foundation for moral and social thought by marrying Christian theology to Aristotelian philosophy. Morality and society could, for Aquinas, only be understood by acknowledging humans as God's creatures, created to be social beings.

Scholasticism, as the development of Thomist ideas came to be called, began to crumble in the 17th century. Who would sustain social and moral order if not God? One of the first to provide an answer was the English philosopher Thomas Hobbes. Humans, Hobbes insisted, are innately not social but egotistical beings, driven by self-interest. In the state of nature, humans were constantly at war.

To find peace and protection, individuals established a "social contract", handing over their liberty to a central power that had absolute authority to maintain order. Fear, not cooperation, drove humans to establish society.

Enlightenment thinkers, Pagden argues, built on Hobbes's critique of scholasticism, and appropriated his account of society, but rejected his vision of human nature. They restored instead the idea of humans as social beings, but freed from theology. Central to this project was the notion of "sentiment": an innate understanding of our common humanity, and of our instinctive desire to feel sympathy.

The idea of sympathy allowed philosophers to give "humankind an identity independent of God" without embracing a Hobbesian view of human nature. "The shift from 'selfishness' to 'sentiment'" provided a means of "recognizing all peoples as of equal worth, and of embracing some kind of common good". The highest expression of this development lies, for Pagden, in Kant's vision of "a society of the citizens of the world": a vision he sees as underpinning international law and institutions such as the UN and the EU.

Both Pagden's retelling of the Enlightenment story, and his defence of cosmopolitanism, are cogent and important. But over the past decade traditional accounts of the Enlightenment have been challenged by the historian Jonathan Israel in an outstanding trilogy of books. Israel sees not Hobbes but the Dutch philosopher Baruch Spinoza as the key figure in establishing an alternative to scholasticism. There were, Israel insists, two Enlightenments, mainstream and Radical. Mainstream thinkers, such as Kant, Voltaire and Hume, accepted compromises with the old order, and were wary of pushing too far ideas of liberty and democracy.

The Radical Enlightenment, drawing inspiration from Spinoza, "sought to sweep away existing structures", insisting that politics and morality had to be grounded on a "radical egalitarianism". The different accounts reveal again that how we frame the Enlightenment has significance well beyond the history books.

'Multiculturalism and its Discontents' by Kenan Malik is published by Seagull Books