  String theory, if it describes nature, is probably strongly coupled. As a
result, one might despair of making any statements about the theory. In the
framework of a set of clearly spelled out assumptions, we show that this is not
necessarily the case. Certain discrete gauge symmetries, combined with
supersymmetry, tightly constrain the form of the effective action. Among our
assumptions are that the true ground state can be obtained from some
perturbative ground state by varying the coupling, and that the actual
numerical value of the low energy field theoretic coupling ${g^2 \over 4\pi}$
is small. It follows that the low energy theory is approximately
supersymmetric; corrections to the superpotential and gauge coupling function
are small, while corrections to the Kahler potential are large; the spectrum of
light particles is the same at strong as at weak coupling. We survey the
phenomenological consequences of this viewpoint. We also note that the string
axion can serve as QCD axion in this framework (modulo cosmological problems).
