Social constructionists maintain that we invent the properties of the world rather than discover them. Is reality constructed by our own activity? Do we collectively invent the world rather than discover it? André Kukla presents a comprehensive discussion of the philosophical issues that arise out of this debate, analysing the various strengths and weaknesses of a range of constructivist arguments and arguing that current philosophical objections to constructivism are inconclusive. However, Kukla offers and develops new objections to constructivism, distinguishing between the social causes of scientific beliefs and the view that all ascertainable facts are constructed.