Our "moral circle" encompasses fellow humans, other primates, dogs, cats and other animals to which we attribute feelings and interests. But as science teaches us more about the inner lives of insects, marine animals and even microbes, it becomes more and more apparent that we might need to include them in our moral circle as well. Furthermore, we may need to bestow moral significance on an upcoming population of artificial intelligences. How can we possibly care for them all, and accommodate their various conflicting interests?

Conventional wisdom has it that if you've never fallen in love, if you've never given birth to a child, if you've never tasted Vegemite... then you can't know what these experiences are like. But is the conventional wisdom correct? This week we're asking if there could in fact be various kinds of what-it-is-like knowledge, not all of which require direct first-hand experience.

It's often said that we're experiencing a crisis in the arts and Humanities, with declining student numbers in subjects that aren't deemed suitable for creating "job-ready graduates", and funding cuts slashing support for the arts. In a world of tight job markets and increasing importance given to STEM subjects, what can we do about it?

The American thinker Wilfrid Sellars died in 1989, and has been remembered as a primarily analytic philosopher. But today, Sellars is being rediscovered by a new generation of Continental philosophers - and, perhaps surprisingly, Marxists. What do these thinkers find in Sellars, and how are his thoughts on science and knowledge being applied to questions of politics and society?

This week marks 80 years since the liberation of Auschwitz at the end of the Second World War. Representation in literature and cinema of the horrors that took place at Auschwitz is fraught with ethical ambiguities, as is the experience of actually visiting Auschwitz, which many people do today. The place stands as a famous memorial, known to all - and yet, this week's guest fears that the lessons of Auschwitz are being forgotten.

Historians are commonly thought of as being a little like archaeologists or scientists - they're in the business of uncovering facts, and then presenting those facts to the public as accurately as possible. But this week we're considering history as a species of narrative, and the historian as someone who doesn't "discover" the meaning of the past but constructs it.

Libertarians are hard to pin down – they have a number of seemingly contradictory commitments that we normally associate with people on either the left or the right of politics. Libertarians like small government, low taxes and free markets – but they also favour things like same-sex marriage and drug legalisation. So what exactly is libertarianism, and where did it come from?

What exactly is it about swearing that gives it its offensive power? None of the standard philosophy-of-language explanations really gets to the bottom of why we swear, why we don't, and what we're doing when we use "obscene" language. This week, the author of a very sweary philosophy book offers some thoughts.

Around the beginning of the 20th century, philosophy began to take what's come to be known as "the linguistic turn". All major philosophical questions, it was argued, were really questions about language, and this conviction would dominate philosophical discourse for the next century. But are philosophers now starting to turn away from the linguistic turn? And what might be coming next?

The Philosopher's Zone is your guide through the strange thickets of logic, metaphysics and ethics.