Abstract
Whilst the concept of causal powers is central to much post-positivist social science in general, and to critical realism in particular, it has not been significantly developed by critical realists since the initial work of Harré and Madden and Bhaskar in the mid-1970s. To deepen our understanding of powers we need to start with a ‘package’ of related terms. In §1 of the paper I introduce this package, clear up some terminological ambiguity and inconsistency, and focus the discussion upon things, properties and powers. The real problems begin when we try to figure out how things, properties and powers relate to one another. In §2 I introduce and evaluate three possible ontologies: an ontology where powers are primary; an ontology where properties are primary; and an ontology where neither properties, powers are primary, but all emerge to form a unity. The last ontology is defended. §3 deals with ambiguities surrounding three other terms that often crop up when discussing powers, namely, dispositional properties, transfactuals and processes. The net result is a far less ambiguous concept of powers, firmly anchored in an ontology of things, properties and powers as a unity.