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 looks at the case of the "naked rambler", Stephen Gough, who is currently in Winchester prison because he refuses to wear clothes in public. Gough benefits from the protection of the state, so is he obliged to stick to social norms as his part of the bargain?

David also looks at "bitcoins" - the digital currency that operates outside the control of any government. Is bitcoin world a libertarian utopia, or a reminder of what Hobbes was talking about: that without someone to lay down the law, you end up with violence and rampant criminality?

Presenter: David Wilson

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 'just' system of law, the law-makers should be kept unaware of their eventual position within that system - they should determine what is best for society from a position outside of society. This famous thought experiment is known as the 'veil of ignorance'.

Rawls served as a soldier in the Second World War and was promoted to Sergeant. After he refused to discipline a fellow soldier, who he thought had done nothing wrong, he was demoted back to Private.

Producer: Tim Dee.

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 sentences in order to put others off committing the same crime.

To see whether Kant's ideas and our justice system can be reconciled, Harry visits Lord Judge who was Lord Chief Justice at the time of the London riots of 2011, when deterrent sentences were handed down. He explains how sentences are determined.

Producer: Melvin Rickarby.

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 is Justice'?

Helping him answer it are barrister Harry Potter, criminologist David Wilson, philosopher Angie Hobbs and historian Alice Taylor.

For the rest of the week Harry, David, Angie and Alice will take us further into the history of ideas about justice with programmes of their own. Between them they will examine civil disobedience, Kant's theory of Justice, Habeas Corpus and philosopher John Rawls' ideas on how to create a just society.

Producer: Melvin Rickarby.

The Russian-American novelist Ayn Rand believed that behaving rationally meant putting your own interests first: you actually have a moral duty to be selfish. Altruism or self-sacrifice are immoral, she claimed, as is asking for help from others. Clearly this goes against most traditional views of ethics, but Rand's views have become influential, particularly in some corners of American politics.

Rand's protege, Nathaniel Branden, developed her ideas to stress the importance of self-esteem - the route to personal fulfilment was feeling good about yourself. Many people, even those who would reject Ayn Rand's core philosophy, have subsequently believed that low self-esteem is at the root of social problems such as crime and educational underachievement, and that we should aim to boost it.

But is self-esteem really such a good thing? As Paul Broks discovers, the research suggests that some people have too much self-esteem, not too little. Maybe the route to a good life is not through feeling good about yourself, but being resilient to knocks that fate deals you.

Naomi Appleton explores the Buddha's Four Noble Truths in a week of programmes asking how do I live a good life. She speaks to a buddhist nun in Edinburgh who used to be a model, and investigates the link between mindfulness and the Four Noble Truths. With contributions from Ani Rinchen Khandro and Professor Willem Kuyken.

Naomi Appleton is the Chancellor's fellow in Religious Studies at the University of Edinburgh.

Hardworking families, alarm clock Britain, shirkers and strivers...there's no doubt that ideas about the moral power and value of hard work are embedded in our culture. But where did these ideas come from? The historian, Justin Champion, explores the ideas of the German thinker and father of sociology Max Weber.

In his most famous book, The Protestant Ethic and the Spirit of Capitalism, Weber set out his idea that the roots of our beliefs about the value of hard work and material success are to be found in the religious thinking of Protestantism, the Puritans especially and Calvin in particular. For them finding a vocation, working hard and achieving material success were evidence that they were one of the elect: the people God had saved from eternal damnation.

Those religious ideas have resonance today, albeit translated into a secular setting: Justin talks to Steve Finn, a former armed robber now involved in running, Blue Sky, a social enterprise that offers employment to ex-offenders so they can turn their lives around. He also hears from the entrepreneur Sara Murray for whom work and life are happily intermingled and whose sense of mission around the success of her company, Buddi, drives her.

Justin also looks at the darker side. With the writer Madeleine Bunting, he explores how our culture's obsession with the "work ethic" can leave people unable to participate feeling deficient and judged.

Producer: Natalie Steed.

Philosopher Jules Evans wants to prove there's been a revival of Aristotle's ideas about flourishing and how to live a good life. "These ideas, which many of you might think are a bit dusty, they are central to modern politics, so the National Office of Statistics now measures national eudaimonic wellbeing, their flourishing."

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 'How do I live a good life'?

Helping him answer it are historian Justin Champion, neuropsychologist Paul Broks , theologian Naomi Appleton and philosopher Jules Evans.

For the rest of the week Jules, Paul, Justin and Naomi will take us further into the history of ideas about the good life with programmes of their own. Between them they will examine Aristotle's idea of flourishing, selfishness, the Protestant work ethic and Buddhism's Four Noble Truths.

Producer: Melvin Rickarby.

There's a tiny bone needle at Creswell Crags in Derbyshire. For archaeologist Matt Pope it's hugely significant. 13,000 years ago local people used it to construct tailored clothing which allowed them to survive and thrive at the very limits of Ice Age civilisation.

Skip forward millennia and the first human visitor to Mars will be protected by a thin skin of man-made fabric, a suit containing the only biological processes for millions of miles. Our ability to create tools that take us into new and hostile environments is, for Matt Pope, the key to man's evolutionary journey.

It's a view he shares with the first philosopher of technology, Ernst Kapp. Living through Germany's rapid industrial revolution Kapp came to believe that we could extend all the functions of the human mind and body through technology. Together, man and his tools would know no limits.