Paul Broks looks at the philosopher Ludwig Wittgenstein and the problem of "other minds". How do I know you are not a zombie who behaves like a human but actually has no consciousness? Even if you are conscious, how can I tell that what I experience as red, you do not experience as blue? I know what's going on in my own mind, but I can never have direct access to what's going on in yours. Such questions have troubled philosophers for centuries, but Wittgenstein thought that most of these...

If a tree falls in a forest and nobody is there to hear it, does it make a sound? That's the kind of head-scratching question that's popularly believed to occupy the time and brains of philosophers. It relates to the ideas of immaterialism proposed by Bishop George Berkeley who asserted that the only things that exist are minds and ideas in those minds. He said that matter didn't really exist and that, in any case, it was unnecessary to complicate things with such a concept. For Berkeley,...

Science is based on fact, right? Cold, unchanging, unarguable facts. Perhaps not, says physicist Tara Shears. Tara is more inclined to follow the principles of the Anglo-Austrian philosopher, Karl Popper. He believed that human knowledge progresses through 'falsification'. A theory or idea shouldn't be described as scientific unless it could, in principle, be proven false. Raised in a Vienna in thrall to Marxism and Freudianism, Popper bristled against these 'sciences' which could adapt...

Barrister Harry Potter asks whether we can believe the evidence of our own eyes. It's a vital question for the justice system today and Harry traces it back to the work of 18th century Philosopher David Hume. Hume, a key figure in the Scottish Enlightenment, wrote about miracles, arguing they were most likely the product of wishful thinking and faulty perception. His arguments are still important for barristers, judges and juries still reliant on eye witness testimony to decide guilt or...

A history of ideas. Presented by Melvyn Bragg but told in many voices. Each week Melvyn is joined by four guests with different backgrounds to discuss a really big question. This week he's asking 'How can I know anything at all?' Helping him answer it are physicist Tara Shears, lawyer Harry Potter, philosopher Clare Carlisle and neuropsychologist Paul Broks. For the rest of the week Tara, Harry, Clare and Paul will take us further into the history of this idea with programmes of their...

How should we love our children? Can we build on the feelings we experience when we see them for the first time, raise them by instinct and personal principles or should we consult the childcare gurus of the internet and the bookshelves? Lisa Appignanesi, the novelist, biographer and author of 'All About Love' suggests that we should turn to the first childcare expert of them all, Jean-Jacques Rousseau. The father of the Romantic movement was one of the first philosophers to consider the...

What is love? Psychotherapist Mark Vernon looks at Freud's ideas on the Greek god Eros, which he saw as a kind of life force running through us, shaping our desires and passions Freud is often thought of as reducing everything to sex, but in his view, for humans even sex isn't even really about sex. Although he started off thinking that sex was about biological release of pressure - like a steam engine - he quickly realised, from working with patients, that it was more about fantasy and...

Giles Fraser discusses gene theory versus altruism with playwright Tom Stoppard whose play The Hard Problem explores the extent to which our genes dictate human acts of love and kindness, and Armand Leroi, the evolutionary biologist who says we are merely programmed to carry out altruistic acts. Producer: Maggie Ayre.

In 416BC the Greek playwright Aristophanes went to a drinking party. The guests included many famous Athenians, including Socrates, and all of them delivered a speech about love. Aristophanes' speech, says presenter Edith Hall, is 'quite simply the most charming account of why humans need a love partner, another half, in world literature.' In the beginning, he says, humans had two bodies - four legs, four arms. These early humans wheeled around the planet doing cartwheels and were blissfully...

A history of ideas. Presented by Melvyn Bragg but told in many voices. Each week Melvyn is joined by four guests with different backgrounds to discuss a really big question. This week he's asking 'What is Love?'. Helping him answer it are theologian Giles Fraser, writer Lisa Appignanesi, classicist Edith Hall and psychotherapist Mark Vernon. For the rest of the week Giles, Lisa, Edith and Mark will take us further into the history of ideas about love with programmes of their own. Between...

If we're to live well together we must first learn to live well with the dead, says Timothy Secret. At traditional Chinese funerals money, and sometimes paper effigies of goods like washing machines and aeroplanes are burned so that the dead might be adequately equipped in the afterlife. To the Western onlooker this can feel strange but Timothy Secret believes we have something to learn. For Confucius, the Chinese teacher and thinker, respect for and obedience to your parents is one of the...

Professor Angie Hobbs asks if the key to harmonious living could be found in Plato's Republic where he proposes that the ideal state be run by philosophers and not by those who seek power for their own ends. Producer: Maggie Ayre.

Is a Free Market the vital foundation of a fair, dynamic and creative society? The father of economics, Adam Smith certainly thought so. Since the publication of 'The Wealth of Nations' in 1776 Smith's thoughts on trade and money-making have come to be seen as the theoretical foundations of a rational and rather uncaring form of pure capitalism. Economist, Dame Kate Barker is keen to put the soul back into Smith, revealing the staunch moral principles that underlined his view of a fair and...

Professor Justin Champion examines Locke's theory of Toleration through the inhabitants of Spitalfields past and present. He goes to Brick Lane whose famous mosque was built as a Huguenot Church and became a synagogue before becoming the centre of Bengali life in London. He meets the Bishop of London, himself of Huguenot descent and local politician Abdal Ullah to discuss religious tolerance then and now Producer: Maggie Ayre.

A history of ideas. Presented by Melvyn Bragg but told in many voices. Each week Melvyn is joined by four guests with different backgrounds to discuss a really big question. This week he's asking 'How should we live together?'. Helping him answer it are economist Kate Barker, historian Justin Champion and the philosophers Timothy Secret and Angie Hobbs. For the rest of the week Kate, Justin, Timothy and Angie will take us further into the history of ideas around this question with...

Rene Descartes, one of the most influential philosophers ever, thought the mind was like an open book that could be read by the light of reason. So there was nothing that we could not access or examine in our own minds. In fact Descartes argued that consciousness was the mind - there was nothing beyond it. Now we see the mind as a labyrinthine cellar full of bric-a-brac and untapped rooms of which consciousness is merely one - and a small one at that. Barry Smith charts this change and...

Philosopher Jules Evans explores Jung and the shadow inside all of us. With archive contributions from Carl Jung and Sigmund Freud; plus fantasy writer Juliet McKenna and Mark Vernon, author of Carl Jung: How to Believe.

Writer AL Kennedy on Existentialist ideas about the individual. Jean Paul Sartre argued that, for humans, 'existence preceded essence'. This means that there is no blueprint or template from which to work - humans are free to make themselves up as they go along. Being an individual comes from the way you negotiate this freedom and the choices you make in the face of it.

Neuropsychologist Paul Broks asks how we can be sure we're the same person as we were yesterday. The philosopher John Locke thought it depended on what we could remember: if we could remember something happening to us, then we were the same person as the person it happened to. But is that true? What if our memories could be downloaded and then uploaded into another body? Would that new person be the same as us? And if so, how much would we care if the body we now inhabit was destroyed? These...

A new history of ideas presented by Melvyn Bragg but told in many voices. Each week Melvyn is joined by four guests with different backgrounds to discuss a really big question. This week he's asking 'What does it mean to be me?' Helping him answer the question are philosopher Barry Smith, neuropsychologist Paul Broks, writer A L Kennedy and philosopher Jules Evans. For the rest of the week Jules, Paul, Alison and Barry take us further into the history of ideas about the self with...

Historian Alice Taylor explores the idea of justice through history, through the lens of power. Who holds the power? Who SHOULD hold the power? Who does that power serve? And who should it protect? One way in which the justice system can remove the power of a citizen is by locking them up, but there are strict laws about how and when that can be done. The writ of Habeas Corpus, part of our legal system almost since the time of Magna Carta, is designed to protect subjects from being...

Criminologist David Wilson looks at 17th century philosopher Thomas Hobbes and his "social contract" theory. Hobbes argued that the only way to secure peace was for everyone to give up their personal freedom and agree to be ruled by a "sovereign". Otherwise, he said, life was liable to be "nasty, brutish and short", with everyone at war with everyone else. In fact, none of us has actually signed a contract to give up our freedom, so what if we disagree with what the state wants to do? David...

Angie Hobbs with Leif Wenar and David Runciman debate and explore one of the most searching ideas of twentieth century legal thought: John Rawls' assertion of the value of a veil of ignorance. John Rawls was a prolific American philosopher and one of the most influential philosophers of the 20th century. His magnum opus, A Theory of Justice defines the principles of Justice as those that "everyone would accept and agree to from a fair position". He proposed that in order to build a truly...

All this week Melvyn Bragg and guests are discussing ideas of Justice. Today lawyer Harry Potter uses the ideas of the philosopher Kant to ask whether deterrent prison sentences are just. He takes us back to the 1700s, when hundreds of petty offences carried the death penalty. And Gordon Finlayson from the University of Sussex explains how Kant's idea that you should never treat people as a means to an end would put him at odds with our justice system today, where people can receive heavy...