ABSTRACT
Processes of non-intentional reasoning may lead even the most competent thinkers to adopt paradoxical philosophical claims, which belief-bias effects may lead them to maintain in the continued absence of warrant. The clash of these unwarranted-and typically absurd (Chapter 5.5)—claims with common sense or science then gives rise to ill-motivated problems, met with philosophical theories built on the very claims that conjured up the problems. Up to now, we have documented this development for two eminent early modern thinkers: Locke and Berkeley. Even when their importance is unreservedly acknowledged, there may be a temptation to think that centuries of intellectual progress separate us from those thinkers and protect us from their misfortunes. In particular, there may be a temptation to think that, if nothing else, the rigour and subtlety of 20th-century analytic philosophy will have neutralised the infl uences of non-intentional reasoning and belief bias. To fi nd out whether this thought is true or overly complacent, we now advance from the 17th to the 20th century and turn from classical to logical empiricism, namely from the fi rst systematic defence of the sensedatum doctrine, by Berkeley, to the doctrine’s most sophisticated development, by A.J. Ayer. We will fi nd that plus ça change, plus c’est pareil: Just like the early modern defence, the sophisticated analytic development of the doctrine presupposes everything it is to show, and more.
