  We revisit arguments that simple models of inflation with a small red tilt in
the scalar power spectrum generically yield an observable tensor spectrum. We
show that criteria for fine-tuning based upon the algebraic simplicity of the
potential depend strongly upon the explicit assumptions they incorporate,
particularly regarding the end of inflation. In addition, some models with
algebraically simple potentials require carefully tuned initial field
configurations, and not all types of fine-tuning are identifiable via the
algebraic simplicity of the potential. Conversely, in the absence of a strong
prior on the mechanism that ends inflation, we demonstrate the existence of
potentials with vanishingly small tensor amplitudes which are natural in terms
of both their algebraic form and initial conditions. We thus argue that
proposed experiments (CMBPol or BBO) which make highly sensitive measurements
of the tensor amplitude cannot definitively rule out the inflationary paradigm.
