In his new book, philosopher Julian Baggini sets up 100 "thought experiments" to help us examine the ideas that govern our world.
In today's Guardian he puts four of the problems to some of the country's leading thinkers, including John Carey, Roger Scruton and Geroge Monbiot.
Now it's your turn. Take a look at the poppadom paradox, nature the artist, pre-emptive justice or sustainable development and let us know your thinking.
