  Motivated by conventional gauge theories, we consider a theory of gravity in
which the Einstein-Hilbert action is replaced by a term that is quadratic in
the Riemann tensor. We focus on cosmological solutions to the field equations
in flat, open and closed universes. The gravitational action is scale
invariant, so the only matter source considered is radiation. The theory can
also accommodate isotropic torsion and this generically removes singularities
from the evolution equations. For general initial conditions the Hubble
parameter H(t) is driven in a seemingly chaotic fashion by torsion to produce
irregularly occuring inflationary regions. In the absence of torsion, the
theory reproduces the standard cosmological solutions of a simple big bang
model. A satisfying feature is that a cosmological constant arises naturally as
a constant of integration, and does not have to be put into the Lagrangian by
hand.
