Books in this series are supposed to be written as introductions to important topics in European history, accessible to undergraduates or even advanced high school students. This book doesn't really meet these requirements. The Enlightenment is structured as a series of linked essays on important topics related to the Enlightenment. These include the social context of the Enlightenment, government and the Enlightenment, gender and the Enlightenment, etc. There is a short introductory chapter which is primarily devoted to historiography of the Enlightenment. The essays are generally quite good but don't really provide the needed overview or basic narrative to accomplish the stated aims for books in this series. This book is most useful as a series of summaries of recent scholarship on the Enlightenment and can be used most usefully by someone who already has significant knowledge in this area. For teachers, I'd recommend using this book as an ancillary to a basic narrative text or even in conjunction with something like Peter Gay's magisterial overview of the Enlightenment. For general readers, this book is most useful as a review of recent scholarship.
To the extent that this book has a theme, it would be the increasing appreciation of the diversity and complexity of the Enlightenment. Outram takes pains to show Enlightenment positions are being more variable than often presented. Following the work of others, she is concerned with rebutting or undermining what has been regarded as a canonical view derived from scholars like Peter Gay that the Enlightenment can be summarized as a liberal reform program. For Outram, as for others, The Enlightenment as a unitary phenomenon does not exist. She, like others, also objects to the tendency to align the Enlightenment with a relatively small group of French intellectuals. Much of this is well taken, and Outram's individual essays are very informative. The discussions of government and the Enlightenment, religion and the Enlightenment, and science and the Enlightenment are particularly good.
On the other hand, there problems with some of her thematic analysis. While the Enlightenment cannot perhaps be easily summarized, at least not in the way suggested by scholars like Peter Gay, the concept retains considerable power and integrity. This is implicitly acknowledged in the title of this book, which is after all, The Enlightenment, not Enlightenments. Implicit in Outram's discussions are recurrent themes such as the importance of reason, skepticism towards received authority, the desire to use knowledge to improve the human condition, etc., which are stated by people like Gay to be basic unifying features of the Enlightenment. Outram's discussions add nuance to traditional views but don't contradict them, and in some ways implicitly endorse them. I think Outram overstates the extent to which recent scholarship has qualified views of the Enlightenment. The recent emphasis on greater geographic variation of the Enlightenment is an example. Peter Gay himself made a good deal out of American participation in the Enlightenment and he was hardly the first scholar to do so. Smith, several Americans, and Kant have long been considered important figures of the Enlightenment. Since when have Glasgow, tidewater Virginia, and Konigsberg been part of the heartland of Europe. Outram disparages the emphasis on French intellectuals yet her own text repeatedly cites the experience and writings of Voltaire, Diderot, etc., undercutting her explicit point.
While Outram is a careful scholar and writer, she also commits some missteps. Her discussion of Hume's epistemology as part of a critique of 18th century science is somewhat offbase. She presents Hume's views correctly but incompletely. Hume thought of himself as carrying out a Newtonian program of research in human psychology and far from undercutting the validity of scientifically generated knowledge, he placed it in a privileged position. Her discussion of 18th century voyages of exploration and the tendency of European intellectuals to project utopian visions onto Pacific island societies is astute but she overlooks the fact there was probably a significant kernal of truth in reports of the utopian nature of these cultures. Because of their biological isolation, these societies lacked many of the epidemic diseases that plagued the rest of the world. For example, a high percentage of Cook's crew probably had disfiguring smallpox scars, something that would have been unknown in Polynesia prior to contact with Europeans.