General relativity as a cosmological attractor of tensor-scalar theories

Tensor-scalar theories of gravity are shown to generically contain an attractor mechanism toward general relativity, with the redshift at the beginning of the matter-dominated era providing the measure for the present level of deviation from general relativity. Quantitative estimates for the post-Newtonian parameters -1, -1, and G \. /G are given, which give greater significance to future improvements of solar-system gravitational tests.