Offers an introduction to the central ideas of philosophy.

Have you ever lain awake at night fretting over how we can be sure of the reality of the external world? Perhaps we are in fact disembodied brains, floating in vats at the whim of some deranged puppet-master? If so, you are not alone - and what's more, you are in exalted company. For this question and other ones like it have been the stuff of philosophical rumination from Plato to Popper. In a series of accessible and engagingly written essays, 50 Philosophy Ideas You Really Need to Know introduces and explains the problems of knowledge, consciousness, identity, ethics, belief, justice and aesthetics that have engaged the attention of thinkers from the era of the ancient Greeks to the present day.

• Brain in a vatCategorical imperativeTheories of punishment Plato's caveGolden ruleLifeboat EarthVeil of perceptionActs and omissionsJust warCogito ergo sumSlippery slopesPrisoner's dilemmaReason and experienceBeyond the call of dutyAnimals are people tooTripartite theory of knowledgeIs it bad to be unlucky?SpeciesismThe mind body problemVirtue ethicsCan bad art be good?What is it like to be a bat?Forms of argumentIntentional fallacyTuring Test - deduction and inductionThe argument from design Ship of TheseusBarber paradoxThe cosmological argumentOther mindsGambler's fallacyThe greatest imaginable beingHume's guillotineSorites paradoxProblem of evil One man's meatThe king of France is baldThe free-will defenceDivine command theoryThe beetle in the boxFaith and reason Boo/hoorah theoryPositive and negative freedomFalsificationEnds and MeansDifference principleGood scienceExperience MachineLeviathanOccam's razor