The really great philosophers have enormous influence over the centuries. To take the measure of their impact is to understand European intellectual history in its broad outlines. Kant, Descartes, Plato and Aristotle himself – who was once known simply as ‘the philosopher’ – have all left indelible marks on western culture. Aristotelian physics and cosmology ran out of steam in the early modern era; physics, chemistry and astronomy snuffed out the explanatory charm of geocentrism, the theory of four elements, and celestial spheres. In the twentieth century aspects of Aristotelian metaphysics have made something of a comeback, but it’s feeble stuff compared to the enduring importance of his theory of the good life. Aristotle’s treatises on ethics have had an almost continuous influence since they were written over 2300 years ago, a phenomenon so striking that specialists, like those contributing to Jon Miller’s recent book on The Reception of Aristotle’s Ethics (Cambridge 2013), have taken the time to study it as a subject all on its own. On the contemporary landscape of moral theory the voice of Aristotle still echoes loud. Virtue ethics is a vigorous contender today and the idea that the perfect exercise of our distinctively human capacities is the key to human success still has legs – we can, if we want, do without Aristotle’s additional thought that our human best is something godlike. I think the enduring appeal of Aristotelian ethics is unsurprising. Once you subtract some of the culturally specific quirks of his views (Greece in the fourth century BC was not a particularly liberal environment) he gives us a highly attractive vision of good human life, one that mere humans can aspire to achieve – it allows for our foibles, but success is by no means easy. The good life it sketches has a clear link to who we are in our real natures; our ‘lower’ selves are to be guided and regulated rather than quashed, desire and pleasure are to be managed not transcended. He claims that we are essentially human, neither beasts nor gods – failure to achieve a transcendent perfection doesn’t leave us wallowing in the muck. And he recognizes the variety of human natures – we aren’t all built for the intellectual perfections that Aristotle, like most philosophers, ranks highest. If the godlike abstract thinker is somehow highest in his view there is still a robust and fully satisfying happiness open to the rest of us. This attractive notion of human nature and its goodness is surely worth another book or two, even after all this time. But my interest in Ethics After Aristotle is a bit different – being an historian of philosophy as well as a philosopher, I’m fascinated by the nitty-gritty of how Aristotle’s influence has grown and changed over time. And while the impact of Aristotelian ethics on Aquinas and certain twentieth century philosophers is well known, it’s not so easy for non-specialists to track the earliest and (to my mind) most fascinating stages of this process. Great philosophers inspire followers, of course. Plato created Platonists, Descartes spawned Cartesians, and Aristotle was no different. But the philosophers who work in the aftermath of such giants don’t necessarily agree with the leaders they follow. Being inspired by great thinkers doesn’t mean treating them like gurus. And so it was with Aristotle. In all aspects of his philosophy he inspired others to work in his mode, within his broad program for doing philosophy, but from the very beginning his students and followers felt perfectly free to disagree with the ‘great man’. Aristotle’s first student, Theophrastus, rejected his views on the ‘unmoved mover’ and took a markedly different view on the nature of human happiness: he left a lot more room for chance events and (as later thinkers complained) didn’t give enough weight to the power of virtue to assure us of a happy life. Others veered towards a kind of hedonism at times – especially when debating against Epicureans and having to answer their criticisms – while the Aristotelians who duked it out with the stringent ethical system of the Stoics inevitably took a different line. All of the ancient Aristotelians drew on the master for inspiration, but at the same time like all good philosophers they responded first and foremost to the debates of their own day. This is the kind of dynamic process that characterizes a healthy philosophical tradition, and Aristotelian ethics is a splendid example of it. In Ethics After Aristotle I try to open up for the non-specialist reader the first few centuries of this tradition, and to show how the various philosophers inspired by him explored the conflicting nuances and loose ends that every great pioneer leaves, how they adapted and developed his core ideas as they debated with all the other philosophical traditions of their day (Epicurean, Stoic and Platonist). Aristotelian ethics is a living tradition, and the same process is still going on today; philosophers are still inspired by dialogue with Aristotle’s works and find in them the resources to contribute to the live debates of our own day. I hope that the longer historical perspective that I provide will give readers a sense not just of how philosophy works over time but also of what it is in Aristotle’s ethical theory that has had the power to attract discerning and reflective people for so many centuries and in so many different cultural environments. The notion that the ideal for human beings is a function of our nature, that a successful life consists in a pattern of actions rather than mere experiences, and that properly developed people who devote their lives to the actions worthy of our species will enjoy their lives, even if times are tough – these have been the core notions of Aristotle’s ethics at every stage of its long and intriguing history. And they are the main ideas explored in Ethics After Aristotle.