Non-viability of gravitational theory based on a quadratic lagrangian

It is shown that physically reasonable solutions of the field equations based on an R 2 lagrangian are possible. (R is the scalar curvature.) However, it is shown that experimental predictions of such a theory are at variance with observations. The most general quadratic lagrangian is also considered and it is shown that the R 2 term must dominate thus invalidating gravitational equations based on a general quadratic lagrangian.