  Metascientific criteria used for explaining or constraining physical space
dimensionality and their historical relationship to prevailing causal systems
are discussed. The important contributions by Aristotle, Kant and Ehrenfest to
the dimensionality of space problem are considered and shown to be grounded on
different causal explanations: {\it causa materialis} for Aristotle, {\it causa
efficiens} for young Kant and an ingenious combination of {\it causa efficiens}
and {\it causa formalis} for Ehrenfest. The prominent and growing r\^ole played
by {\it causa formalis} in modern physical approaches to this problem is
emphasized.
