  We present theoretical ground state energies and their uncertainties for
p-shell nuclei obtained from chiral effective field theory internucleon
interactions as a function of chiral order, fitted to two- and three-body data
only. We apply a Similary Renormalization Group transformation to improve the
numerical convergence of the many-body calculations, and discuss both the
numerical uncertainties arising from basis truncations and those from omitted
induced many-body forces, as well as chiral truncation uncertainties. With
complete Next-to-Next-to-Leading (N2LO) order two- and three-body interactions,
we find significant overbinding for the ground states in the upper p-shell, but
using higher-order two-body potentials, in combination with N2LO three-body
forces, our predictions agree with experiment throughout the p-shell to within
our combined estimated uncertainties. The uncertainties due to chiral order
truncation are noticeably larger than the numerical uncertainties, but they are
expected to become comparable to the numerical uncertainties at complete N3LO.
