  We develop a statistical framework for the rheology of dense, non-Brownian
suspensions, based on correlations in a space representing forces, which is
dual to position space. Working with the ensemble of steady state
configurations obtained from simulations of suspensions in two dimensions, we
find that the anisotropy of the pair correlation function in force space
changes with confining shear stress ($\sigma_{xy}$) and packing fraction
($\phi$). Using these microscopic correlations, we build a statistical theory
for the macroscopic friction coefficient: the anisotropy of the stress tensor,
$\mu = \sigma_{xy}/P$. We find that $\mu$ decreases (i) as $\phi$ is increased
and (ii) as $\sigma_{xy}$ is increased. Using a new constitutive relation
between $\mu$ and viscosity for dense suspensions that generalizes the
rate-independent one, we show that our theory predicts a Discontinuous Shear
Thickening (DST) flow diagram that is in good agreement with numerical
simulations, and the qualitative features of $\mu$ that lead to the generic
flow diagram of a DST fluid observed in experiments.
