  In this work we generalize the MacDowell-Mansouri theory of gravity using
strict 2-groups. To achieve this, we construct the categorical generalization
of the ISO(4,1) group, which we call the de Sitter 2-group. We then proceed to
generalize the MacDowell-Mansouri theory in two different ways. First, as a
Yang-Mills-type theory, where the symmetry is explicitly broken to obtain an
Einstein-Cartan theory coupled to Kalb-Ramond fields. And second, by using the
categorical generalization of the BF theory, called 2-BF theory, which after
the addition of some symmetry breaking and constraint terms gives the same
Einstein-Cartan theory coupled to Kalb-Ramond fields plus some extra
topological terms.
