  The application of effective field theory (EFT) methods to nuclear systems
provides the opportunity to rigorously estimate the uncertainties originating
in the nuclear Hamiltonian. Yet this is just one source of uncertainty in the
observables predicted by calculations based on nuclear EFTs. We discuss the
goals of uncertainty quantification in such calculations and outline a recipe
to obtain statistically meaningful error bars for their predictions. We argue
that the different sources of theory error can be accounted for within a
Bayesian framework, as we illustrate using a toy model.
