You can find the details here. The question this year is:
‘What is philosophy? How is it possible?
What can it expect to achieve?’
Entries may address the topic in a variety of ways, and could ask what makes a problem or an approach philosophical. Are there particular subject areas for philosophy? Have these changed over time? Are they different in different traditions? Is progress achievable in philosophy? How might progress be assessed? If there has been philosophical progress, where is it to be found? If not, why is this? And if progress in any non-contentious sense is not possible, does philosophy still have a point?
The prize is £2,500. If you can answer this set of questions adequately, you deserve the money!