  The slow-roll approximation to inflation is ultimately justified by the
presence of inflationary attractors for the orbits of the solutions of the
dynamical equations in phase space. There are many indications that the
inflaton field couples nonminimally to the spacetime curvature: the existence
of attractor points for inflation with nonminimal coupling is demonstrated,
subject to a condition on the inflaton potential and the value of the coupling
constant.
