The Westminster sex scandal has shone a light on yet more public figures behaving badly. The behaviour may not be new, but people appear to be far less tolerant of it. This raises questions about where our morality comes from and whether human beings can become collectively more ethical. Is this apparent shift in social mores an example of how our collective moral standards have improved? Or has an increasingly sexually-permissive culture - in which even children as young as ten are now "sexting" - created the monster from which many now recoil? It's not just about sex; there is an increasing public intolerance of tax havens, but does that mean we are any less greedy? While some argue that individualism has made us more selfish, others say it has encouraged a morality based on considered personal conscience rather than on a consensus which can be flawed. This week, Nicola Sturgeon apologised on behalf of the Scottish Government to all men convicted of now-abolished homosexual offences. Conversely, slavery - once thought acceptable - is now illegal. Are such retrospective judgements not a clear sign of moral progress? To what extent should moral values change as the tide of public opinion ebbs and flows? There are far fewer people who think homosexuality is wrong, but those who continue to think it say that morality should not be decided by a majority vote and does not change over time. If they are right, how can we even begin to define what we mean by moral progress, let alone attempt to measure it?

Producer: Dan Tierney.