long list of books is not what is required, but you should certainly mention two or three. Preferably they should be in different subject areas, and offer contrasting viewpoints. It is important to put the stress on what you learned from them - how they excited/shocked/annoyed you, or confounded your expectations. Remember that if Oxford is your intended destination they are almost certain to ask questions about one or more of the books at interview, so make sure you have read them thoroughly! A good line to take in the PS is what it was that inspired you to read the book in each case - and make sure they are not standard textbooks. I encourage my own students to read a range of stimulating books in economics, politics, philosophy and critical thinking, and so I append my 2010 list of favourites.

Ariely – Predictably Irrational: The Hidden Forces that Shape our Decisions
Ball – Critical Mass: How One Thing Leads to Another
Bishop - Essential Economics
Blackburn – Think: A Compelling Introduction to Philosophy
Buchholz – New Ideas from Dead Economists
Cassidy – How Markets Fail: The Logic of Economic Calamities
Conway – Fifty Economics Ideas
Dixit and Nalebuff - Thinking Stategically (also ‘The Art of Strategy’)
Fisher – Critical Thinking: An Introduction
Frank – What’s the Matter with Kansas?
Friedman - The World Is Flat
Goodwin – Using Political Ideas
Harford – The Undercover Economist
Harford - The Logic of Life
Heilbroner – The Worldly Philosophers
Hoffman & Graham – An Introduction to Political Theory
Joyce – Teach Yourself 101 Key Ideas in Politics
Kay – The Truth about Markets
Kay - Everlasting Light Bulbs
Krugman – The Accidental Theorist and Other Dispatches from the Dismal Science
Krugman - Peddling Prosperity
Law – The Philosophy Gym: 25 Short Adventures in Thinking
Lee, Simon Lee & Beech – The Conservatives under David Cameron – Built to Last?
Levitt & Dubner – Freakonomics; A Rogue Economist explores the Hidden Side of Everything
Levitt & Dubner – Superfreakonomics: Global Cooling, Patriotic Prostitutes and why Suicide Bombers should buy Life Insurance
Mason – Meltdown: The End of the Age of Greed
Miller - Game Theory At Work
Ormerod – Why Most Things Fail: Evolution, Extinction and Economics
Pessin – The God Question
Pirie – How to Win Every Argument: the Use and Abuse of Logic
Ritzer – The McDonaldisation of Society
Roubini – Crisis Economics
Strathern - Dr. Strangelove's Game
Surowiecki - The Wisdom of Crowds
Thaler & Sunstein – Nudge
Thomas – A Long Time Coming – how Obama Won
Warburton – Thinking from A to Z
Wolff - An Introduction to Political Philosophy
Young – The Hugo Young Papers: Thirty Years of British Politics Off The Record

I hope this is helpful. Good luck with your application.