The Enlightenment is a term so often used and abused that it might no longer be clear what it stands for. It has been widely viewed as the source of everything that is peculiarly modern, from liberal constitutions to alienating technology. Its legacy is now invoked by diverse groups and parties, sometimes advocating very different policies. In the stormy debates surrounding the publication in 2005 of a caricature of the prophet Muhammad in a Danish newspaper, Muslim protesters argued that the blasphemous images ran against the Enlightenment values of toleration and respect for minorities. Their opponents cast the Muslim response itself as opposed to Enlightenment notions of the freedom of the press and the right to self-expression. Was there ever a set of distinctive ideas we may safely refer to as ‘the Enlightenment’?

Historians usually use the term to refer to the 18th century (in its shorter or longer versions) and especially to the intellectual developments brought to the fore by such luminaries as Voltaire, Diderot, Rousseau, Hume, Smith and Kant. Yet this notion is burdened by the common tendency to assume that since two major revolutions took place in the late 18th century – the American and the French – they must have been prompted or caused by Enlightenment ideas.

The traditional view of the Enlightenment, initially crafted by Romantic and anti-revolutionary authors in the 19th century, cast it as a militantly republican, anti-religious and mainly French movement. Some residues of this view were still apparent in post-war works by authors who tried to reclaim the legacy of the Enlightenment (or some of its vestiges), such as Peter Gay’s two-volume study The Enlightenment: An Interpretation (1966 and 1969) or Isaiah Berlin’s essay on the Counter-Enlightenment in Against the Current (1979). However, this perspective has been revised since the 1980s. An important collection of essays, The Enlightenment in National Context, edited by Roy Porter and Mikuláš Teich (1981), inspired a wealth of works on the various shades and colours of 18th-century thought, from Greece and Russia to Scotland and Portugal. An increasing number of publications also highlighted the different intellectual issues at stake in different contexts, often within a single country. This awareness led to J.G.A. Pocock’s call, in Barbarism and Religion, vol. 1: The Enlightenments of Edward Gibbon (1999), to treat the definite article with suspicion: instead of speaking of the Enlightenment we should think of different Enlightenments sharing some family resemblance.

These suggestions ushered in more nuanced investigations into the configurations of Enlightenment thought, while significantly widening the previously narrow geographical focus. Whereas we now know much more about local manifestations of Enlightenment across Europe and beyond, we have also been exposed to the contribution of religious thinkers – Jewish and Catholic alongside the Protestants – to Enlightenment ideas, as related, for example, in Jonathan Sheehan’s The Enlightenment Bible (2005) and David Sorkin’s The Religious Enlightenment (2008). Others have suggested that the Enlightenment can be seen as a unitary movement, if viewed from the perspective of its common media and social venues. Books, pamphlets, journals, as well as the different ways of reading and interpreting them, have stood at the centre of the work of Roger Chartier (The Cultural Origins of the French Revolution, 1991) and Robert Darnton (The Forbidden Bestsellers of Pre-Revolutionary France, 1996; The Devil in the Holy Water, 2009). Darnton focused on what he called the ‘Grub Street hacks’ of the French Enlightenment: by vulgarising the works of the more serious philosophers, these authors contributed to the diffusion of simplified ideas through libel, pornography and folksong.

Invigorating as the broader perspectives were, they also seem to have undermined the efforts to define the Enlightenment as a whole. It is now problematic to determine when the Enlightenment began and ended, or how different its ideas were from those of previous and subsequent reform movements. In the last decade attempts have been made to regain a more panoramic view of the Enlightenment, while taking into account the wealth of new information on its different manifestations. In his three-volume project (so far) Jonathan Israel focused on a minority of radical thinkers, whose thought he traced back to Spinoza and the 17th-century Dutch Republic. These thinkers, among them Diderot and Condorcet, were contrasted with such ‘moderate’ authors as Locke and Voltaire, who were willing in different circumstances to make compromises with the powers that be. The roots of modern human rights, equality and democracy were resolutely ascribed by Israel to the radicals (Radical Enlightenment, 2001; Enlightenment Contested, 2005; Democratic Enlightenment, 2011). John Robertson followed a different path, comparing Enlightenment thought in Scotland and Naples in The Case for the Enlightenment (2005). According to Robertson, comparable political and cultural contexts, as well as engagement with the same authors, led to similar preoccupations. Both Scots and Neapolitans abandoned religious radicalism and centred their efforts on gradual economic and political reform.

Focusing on France, Dan Edelstein investigated the actual uses of ‘Enlightenment’ in the 18th century. According to his study The Enlightenment: A Genealogy (2010), this was a contemporary way to make sense of recent cultural changes. Edelstein linked its rise to the early 18th-century Quarrel of the Ancients and the Moderns, a debate over the respective merits of what we would call ‘Enlightenment Europe’ and the time-hallowed achievements of classical antiquity. My own book, Language and Enlightenment, (2012) shows how cross-European discussions, such as the debate on the emergence of language and society, were distinctly manifested in particular settings (in this case, Berlin).

These different perspectives on the Enlightenment are perhaps inevitable, given that our own use of the term differs from that of 18th-century authors. While we refer by ‘Enlightenment’ to a historical period, contemporaries usually saw it as a tendency, a frame of mind or a set of cultural achievements. Even if they thought Lumières or Aufklärung typical of their own time (the English term was not commonly used), it was usually not seen as limited or unique to that period. Immanuel Kant’s essay of 1784, ‘What is Enlightenment?’, opens with the statement ‘Enlightenment is man’s emergence from his self-imposed immaturity’. This is a plea for independent thinking, as expressed in his call ‘dare to know’ (sapere aude). It is in this sense that Kant saw his own time as a not yet enlightened age, but rather an age of enlightenment. According to this view, the Enlightenment might well still be a work in progress. Yet historians have to distinguish carefully between such normative assessments and historiographical markers; our 18th-century Enlightenment is not Kant’s perpetual process.

Avi Lifschitz is Lecturer in European History at University College London.