  We consider the spectral action within the context of a 4-dimensional
manifold with torsion and show that, in the vacuum case, the equations of
motion reduce to Einstein's equations, securing the linear stability of the
theory. To subsequently investigate the nonvacuum case, we consider the
spectral action of an almost commutative torsion geometry and show that the
Hamiltonian is bounded from below, a result which guarantees the linear
stability of the theory.
