It is not hard to find examples of misplaced confidence in the triumph of reason. Condorcet in his Sketch for a Historical Picture of the Progress of the Human Mind (1795) claimed that disappearance of superstition and prejudice and an understanding of the rights of man would inevitably result in progress of humankind toward perfection. But other Enlightenment thinkers had more critical views about the capacity of reason and the inevitability of human progress.

It is this darker side of Enlightenment thought that the philosopher Genevieve Lloyd brings to light in this book. She does so through a close reading of a wide variety of texts, including Montesquieu’s Persian Letters, Voltaire’s Philosophical Dictionary, Hume’s essay, ‘The Sceptic’, Adam Smith’s Theory of Moral Sentiments, d’Alembert’s and Diderot’s writings on the Encyclopedia project, Diderot’s Rameau’s Nephew, and Kant’s essay, ‘Perpetual Peace’. These are not the works for which the authors are best known. Smith, for example, is more famous for his economic theory, Hume for his books on human nature and human understanding. But they serve Lloyd’s purposes by bringing out neglected or marginalised aspects of Enlightenment thought.

In her exploration of these texts, Lloyd has a number of objectives. One of them is to question, if not entirely to repudiate, the distinction between the Enlightenment as the age in which reason, science, and the search for universal truth ruled and the later Romantic period in which emotion, individuality, and creativity were celebrated. Enlightenment thinkers were also concerned with the passions and their influence on human thought and behaviour; they recognised and tried to appreciate individual difference, and they celebrated human ingenuity and its ability to overturn accepted truths. The texts she examines illustrate the problem of drawing boundaries between periods of intellectual history or differentiating them by means of essential characteristics.

But Lloyd has more important objectives. She aims to question the dominance of impersonal rationality that features in most accounts of Enlightenment thought. In doing so, she is continuing a line of enquiry central to the development of her feminist critique of Western philosophy in Man of Reason (1984) and elsewhere. The texts she examines do not valorise reason; they emphasise the central role of sympathy and imagination. Hume is well known for his belief that passion, not reason, is the driving force of moral life. But it is Smith’s theory of moral sentiment that comes closer to the position favoured by Lloyd. Our ability to sympathise with others and to imagine ourselves in their place provides for him the basis for moral judgement. Through reciprocal engagement with others he thinks that we can achieve an objective perspective that does not ignore our emotional propensities or the bonds we have with particular others.

Lloyd’s other important purpose is to answer a question that occurs to all students of the Enlightenment: what is the Enlightenment to us? Is it an intellectual period that is over and done with, or are we, for better or worse, continuing its work? Through the texts she examines, Lloyd presents enlightenment as a continuing process rather than a set of doctrines. For Kant enlightenment means coming to maturity through use of our capacity to reason. Diderot and d’Alembert present it as a never-ending search for knowledge useful to humankind, Montesquieu as a self-critical quest for mutual understanding, Voltaire as a struggle against dogmatism, whatever form it takes.

This account of the Enlightenment enables Lloyd to meet criticisms that have often been made against it. Enlightenment does not lead to paternalistic condescension toward ‘backward’ people of other cultures. In his Persian Letters, Montesquieu imagines the response of travellers from the Muslim world to their encounters with European customs and beliefs. He uses this view from the outside to highlight the absurdities and injustices in his society. But he also uses his tale to show how people from very different cultures can come to appreciate each other’s perspectives and learn from them.

Enlightenment is often associated with militant atheism, but as Lloyd points out, many Enlightenment thinkers were neither atheists nor militant. What they wanted to encourage was moral thinking that did not appeal to the dogmas of any religion. And Enlightenment thinkers were not afraid to criticise the pretensions of rationality. Both Hume and Kant are notable for their critique of those who thought that they could discover the nature of reality through reason.

As Lloyd demonstrates, the Enlightenment as an intellectual period was a complex phenomenon. It is associated with confidence in the power of human reason, but it was beset with instabilities and uncertainties. It invites us to take a cosmopolitan point of view, but it was not able to provide a foundation for its universalism. It claims to provide a rational morality, but the objectivity it offers is conditional and uncertain. By drawing attention to its darker side, her book presents us with an Enlightenment congenial to contemporary times – to an age in which people are sceptical of the claims of reason, doubt the existence of universal moral truths, and reject reductive attempts to ground morality and politics. Her version of the Enlightenment is sensitive to the perspectives of outsiders, regards objectivity as something that can only be achieved through communication, imagination, and sympathy, and gives a large role to the emotions and the concerns of ordinary social life. Hers is in many ways a conservative version of the Enlightenment – one that does not force us to challenge our deepest beliefs, attachments, and emotional propensities in the name of reason.

What it glides over are the radical changes in moral consciousness that inspired the texts that Lloyd discusses. Behind Smith’s conception of moral objectivity, Montesquieu’s interest in the perspective of outsiders, Voltaire’s biting satire against ideologues and abuses of power, and Diderot’s and d’Alembert’s desire to compile knowledge that everyone can find useful are two radical ideas: that individuals, whoever and wherever they are, are entitled to equal concern and respect; and that government and social institutions should be judged on how well they promote the welfare of all citizens. It is acceptance of these ideas that gives reason such a revolutionary role. If individuals are supposed to be moral and political equals, then discrimination against women, slavery, or subjugation of other races are open to serious criticism. If a government is supposed to promote the well-being of citizens, then reason can reveal ways in which institutions fail.

Although Lloyd skips over the more radical aspects of Enlightenment thought, she certainly does not deny them. She takes them for granted – another indication that we live in the shadow of the Enlightenment. What her book offers is a reconciliation of Enlightenment demands for radical critique with an attention to human passions and individual differences, and with an appreciation of the uncertainties that beset any attempt to exercise reason. It is a tribute to the creativity of the thinkers of the Enlightenment that these ideas for reconciliation come out of the Enlightenment itself.