Melvyn Bragg and guests discuss the concept of friendship. In Greek and Roman times, friendship was thought of as being an essential constituent of both a good society and a good life; a good society because it lay at the heart of participative civic democracy; a good life because it nurtured wisdom and happiness. It is this period which gives us the texts on friendship which, to this day, are arguably the most important of their kind. Amongst their authors is Aristotle, who engaged in one of the great philosophical discussions on the subject. For Aristotle, friendship could fall into three categories: it could be based on utility, pleasure or goodness. In its latter state, Aristotle described it as being 'a single soul dwelling in two bodies'. So how did the Ancients establish the parameters of the true nature of friendship in the literature and philosophy that followed? How have different forms of friendship helped or hindered creativity and intellectual pursuit? What has been the apparent relationship between friendship and power? And what of the darker aspects of friendship - jealousy, envy and exploitation? With Angie Hobbs, Lecturer in Philosophy at the University of Warwick; Mark Vernon, Visiting Lecturer in Philosophy at Syracuse University and London Metropolitan University; John Mullan, Professor of English at University College London.

Melvyn Bragg and guests discuss relativism, a philosophy of shifting sands. "Today, a particularly insidious obstacle to the task of educating is the massive presence in our society and culture of that relativism which, recognizing nothing as definitive, leaves as the ultimate criterion only the self with its desires. And under the semblance of freedom it becomes a prison for each one, for it separates people from one another, locking each person into his or her own 'ego'." Pope Benedict XVI, in a speech given in June 2005, showed that the issue of relativism is as contentious today as it was in Ancient Greece, when Plato took on the relativist stance of Protagoras and the sophists. Relativism is a school of philosophical thought which holds to the idea that there are no absolute truths. Instead, truth is situated within different frameworks of understanding that are governed by our history, culture and critical perspective. Why has relativism so radically divided scholars and moral custodians over the centuries? How have its supporters answered to criticisms that it is inherently unethical? And if there are universal standards such as human rights, how do relativists defend culturally specific practices such as honour killings or female infanticide? With Barry Smith, Senior Lecturer in Philosophy at Birkbeck College, University of London; Jonathan Rée, freelance philosopher who holds visiting professorships at the Royal College of Art and Roehampton University; Kathleen Lennon, Senior Lecturer in Philosophy at the University of Hull.

Melvyn Bragg and guests discuss the importance of the oath in ancient Greece and Rome, The importance of oaths in the Classical world cannot be overstated. Kings, citizens, soldiers, litigants all swore oaths, inviting divine retribution if they proved false to their word. Oaths cemented peace treaties, they obliged the Athenian citizenry to protect their democracy, they guaranteed the loyalty of the Roman army to its Emperor and they underpinned the legal systems of Athens and Rome. And in Homer's epic poem, The Iliad, it is a broken oath to settle the dispute between Menelaus and Paris that leads the Greeks to storm Troy in pursuit of Helen. But how did the Classical world come to understand the oath? Why did oaths come to occupy such a central place in the political, social and legal life of the Athenian State? And what role did oath-making play in the expanding Roman Empire? With Alan Sommerstein , Professor of Greek at the University of Nottingham;Paul Cartledge , Professor of Greek History at the University of Cambridge; Mary Beard , Professor in Classics at the University of Cambridge

Melvyn Bragg and guests discuss the great 17th century political philosopher Thomas Hobbes who argued: "During the time men live without a common power to keep them all in awe, they are in that condition which is called war; and such a war as is of every man against every man". For Hobbes, the difference between order and disorder was stark. In the state of nature, ungoverned man lived life in "continual fear, and danger of violent death". The only way out of this "solitary, poor, nasty, brutish, and short" existence, he said, was to relinquish all your freedom and submit yourself to one all powerful absolute sovereign. Hobbes' proposal, contained in his controversial and now classic text, Leviathan, was written just as England was readjusting to life after the Civil War and the rule of Oliver Cromwell. In fact, in his long life Hobbes’ allegiance switched from Charles I to Cromwell and back to Charles II. But how did the son of a poor clergyman end up as the most radical thinker of his day? Why did so many of Hobbes' ideas run counter to the prevailing fondness for constitutionalism with a limited monarchy? And why is he regarded by so many political philosophers as an important theorist when so few find his ideas convincing? With Quentin Skinner, Regius Professor of History at the University of Cambridge; David Wootton, Professor of History at the University of York; Annabel Brett, Senior Lecturer in Political Thought and Intellectual History at Cambridge University.

Melvyn Bragg and guests discuss the American philosophy of pragmatism. A pragmatist "turns away from abstraction and insufficiency, from verbal solutions, from bad apriori reasons, from fixed principles, closed systems, and pretended absolutes and origins. He turns towards concreteness and adequacy, towards facts, towards action and towards power". A quote from William James' 1907 treatise Pragmatism: A New Name for Some Old Ways of Thinking. William James, along with John Dewey and Charles Sanders Peirce, was the founder of an American philosophical movement which flowered during the last thirty years of the nineteenth century and the first twenty years of the 20th century. It purported that knowledge is only meaningful when coupled with action. Nothing is true or false - it either works or it doesn't. It was a philosophy which was deeply embedded in the reality of life, concerned firstly with the individual's direct experience of the world he inhabited. In essence, practical application was all. But how did Pragmatism harness the huge scientific leap forward that had come with Charles Darwin's ideas on evolution? And how did this dynamic new philosophy challenge the doubts expressed by the Sceptics about the nature and extent of knowledge? Did Pragmatism influence the economic and political ascendancy of America in the early 20th century? And did it also pave the way for the contemporary preoccupation with post-modernism? With A C Grayling, Professor of Applied Philosophy at Birkbeck College, University of London and a Fellow of St Anne's College, Oxford; Julian Baggini, editor of The Philosophers' Magazine; Miranda Fricker, Lecturer in Philosophy at Birkbeck College, University of London.

Melvyn Bragg and guests discuss the Cynics, the performance artists of philosophy. Eating live octopus with fresh lupins, performing intimate acts in public places and shouting at passers by from inside a barrel is behaviour not normally associated with philosophy. But the Cynics were different. They were determined to expose the meaninglessness of civilised life by action as well as by word. They slept rough, ate simply and gave their lectures in the market place. Perhaps surprisingly, their ideas and attitudes were immensely popular in the ancient world. But how coherent was cynicism as a philosophy? What was its influence on literature and politics and is there any truth to the contention that Jesus himself was influenced by the Cynics? With Angie Hobbs, Lecturer in Philosophy, University of Warwick; Miriam Griffin, Fellow of Somerville College, Oxford; John Moles, Professor of Latin, University of Newcastle.

Melvyn Bragg and guests discuss Karl Marx. "Workers of the World Unite! You have nothing to lose but your chains", "Religion is the opium of the people", and "From each according to his abilities, to each according to his needs". That should be enough for most of you to work out whom Radio 4 listeners have voted as their favourite philosopher: the winner of the In Our Time Greatest Philosopher Vote, chosen from 20 philosophers nominated by listeners and carried through on an electoral tidal wave of 28% of our 'first-past-the-post' vote is the communist theoretician, Karl Marx.So, when you strip away the Marxist-Leninism, the Soviet era and later Marxist theory, who was Karl Marx? Where does he stand in the history of philosophy? He wrote in his Theses on Feuerbach, "Philosophers have only interpreted the world in various ways, the point, however, is to change it" - which begs the question, is he really a philosopher at all?With Anthony Grayling, Professor of Philosophy at Birkbeck College, University of London; Francis Wheen, journalist and author of a biography of Karl Marx; Gareth Stedman Jones, Professor of Political Science at Cambridge University.

Melvyn Bragg and guests discuss beauty and its qualities."Beauty is truth, truth beauty, - that is all Ye know on earth, and all ye need to know."That was John Keats' emphatic finale to his Ode on a Grecian Urn. It seems to express Plato's theory of aesthetics, his idea that an apprehension of beauty is an apprehension of perfection and that all things in our shadowy realm are botched representations of perfect 'forms' that exist elsewhere. Beauty is goodness and, for Plato, the ultimate of all the forms is 'The Good'.But does beauty really have a moral quality? And is it inherent in things, or in the mind of the observer? How much influence have Plato's ideas had on the history of aesthetics and what has been said to counter or develop them?With Angie Hobbs, Lecturer in Philosophy at the University of Warwick; Susan James, Professor of Philosophy at Birkbeck College, University of London; Julian Baggini, Editor of The Philosophers' Magazine.

Melvyn Bragg and guests discuss the story of Abelard and Heloise, a tale of literature and philosophy, theology and scandal, and above all love in the high Middle Ages. They were two of the greatest minds of their time and Abelard, a famous priest and teacher, wrote of how their affair began in his biography, Historia Calamitatum, “Her studies allowed us to withdraw in private, as love desired, and then with our books open before us, more words of love than of reading passed between us, and more kissing than teaching. My hands strayed oftener to her bosom than to the pages; love drew our eyes to look on each other more than reading kept them on our texts”. Years later, when she was an Abbess at the head of her own convent, Heloise wrote to Abelard: “Even during the celebration of Mass, when our prayers should be purer, lewd visions of those pleasures take such a hold upon my unhappy soul that my thoughts are on their wantonness instead of on prayers”. With Anthony Grayling, Professor of Philosophy at Birkbeck College, University of London; Henrietta Leyser, Medieval Historian and Fellow of St Peter’s College, Oxford; Michael Clanchy, Emeritus Professor of Medieval History at the Institute of Historical Research.

Melvyn Bragg and guests discuss Stoicism, the third great philosophy of the Ancient World. It was founded by Zeno in the fourth century BC and flourished in Greece and then in Rome. Its ideals of inner solitude, forbearance in adversity and the acceptance of fate won many brilliant adherents and made it the dominant philosophy across the whole of the Ancient World. The ex-slave Epictetus said "Man is troubled not by events, but by the meaning he gives them". Seneca, the politician, declared that "Life without the courage for death is slavery". The stoic thoughts of Marcus Aurelius, the philosopher emperor, provided a rallying point for empire builders into the modern age.Stoicism influenced the Christian church, had a big effect on Shakespeare and Renaissance drama and may even have given the British their 'stiff upper lip', but it's a philosophy that was almost forgotten in the 20th century. Does it still have a legacy for us today?With Angie Hobbs, Lecturer in Philosophy, University of Warwick; Jonathan Rée, philosopher and historian; David Sedley, Laurence Professor of Ancient Philosophy, University of Cambridge.