  Gravitational stability of torsion and inflaton potential in a
four-dimensional spacetime de Sitter solution in scalar-tensor cosmology where
Cartan torsion propagates is investigated in detail. Inflaton and torsion
evolution equations are derived by making use of a Lagrangean method. Stable
and unstable modes for torsion and inflatons are found. Present astrophysical
observations favour a stable mode for torsion since this would explain why no
relic torsion imprint has been found on the Cosmic Background Radiation in the
universe.
