  We discuss the source of the apparent ambiguities arising in the calculation
of the dynamics of binary black holes within the Post-Newtonian framework.
Divergences appear in both the near and far zone calculations, and may be of
either ultraviolet (UV) or infrared (IR) nature. The effective field theory
(EFT) formalism elucidates the origin of the singularities which may introduce
apparent ambiguities. In particular, the only (physical) 'ambiguity parameters'
that necessitate a matching calculation correspond to unknown finite size
effects, which first appear at fifth Post-Newtonian (5PN) order for
non-spinning bodies. We demonstrate that the ambiguities linked to IR
divergences in the near zone, that plague the recent derivations of the binding
energy at 4PN order, both in the ADM and 'Fokker-action' approach, can be
resolved by implementing the so-called 'zero-bin' subtraction in the EFT
framework. The procedure yields ambiguity-free results without the need of
additional information beyond the PN expansion.
