ABSTRACT
Towards the end of his professional life, Popper introduced a new concept into his philosophical system with which he sought to extend his critical fallibilist epistemology. This innovation, centring on a conjectural division of the universe into three worlds of experience, has not always been well received by his fellow philosophers. Indeed, as Notturno (2000, p. 139) notes, 'most contemporary philosophers regard World 3 as an unfortunate product of Popper's old age' (see, for example, Gellner, 1993; Haack, 1995). But this is an unfair judgement, resulting in the misunderstanding of an important development of Popper's thought. The 'Three Worlds' hypothesis will be critically evaluated, and implications will be examined, especially related to child development, language and education.
