Space, time and natural kinds

Einsteinââ"šÂ¬Ã¢"žÂ¢s special theory, as interpreted by Herman Minkowski, suggests that an understanding of space and time requires the replacement of three-dimensional space and one dimensional time with a four-dimensional spacetime continuum, as a natural kind of thing with a characteristic, geometrical, structure. Issues of space and time in general, and of special relativity in particular, are not addressed in Bhaskarââ"šÂ¬Ã¢"žÂ¢s A Realist Theory of Science, and their treatment in subsequent realist writings has been patchy and indecisive. Some of Bhaskarââ"šÂ¬Ã¢"žÂ¢s observations in later writings, including his defence of fundamental ontological asymmetries between space and time, and between present, past and future, appear incompatible with a relativistic perspective. Equally problematic, from a critical realist perspective, is the apparent ontological prioritisation of events, and causation as action-by-contact, within the Minkowski interpretation of special relativity. This paper argues that the four-dimensional spacetime continuum of special relativity occupies its own level at the base of the ontological hierarchy of natural kinds, providing lower-order components and laws for higher-order physical, chemical, biological and social structures. While providing no definitive reconciliation of relativistic and realist perspectives, this paper does suggest that A. N. Whiteheadââ"šÂ¬Ã¢"žÂ¢s idea of atomic events, or ââ"šÂ¬Ã‹Å“actual occasionsââ"šÂ¬Ã¢"žÂ¢, could pave the way for some possible future reconciliation.