  The Multiple Point Criticality Principle (MPCP) states that action parameters
- in for example a field theory - take on values corresponding to the junction
of a maximum number of phases in the phase diagram of a system that undergoes
phase transitions. The phases to which physical significance is ascribed are
normally regarded as artifacts of a regulation procedure. In the context of a
Y-M lattice gauge theory, the MPCP is applied to the system of different
(Planck scale) lattice phases that can be provoked using a suitably generalised
action with a gauge group that is taken to be the Planck scale predecessor to
the Standard Model Group (SMG) - namely the $N_{gen}$-fold Cartesian product of
the SMG. Here $N_{gen}$ is the number of fermion generations. Ambiguities under
mappings of the gauge group $SGM^{N_{gen}}$ onto itself result in the Planck
scale breakdown to the diagonal subgroup which is isomorphic to the usual SMG.
Assuming the validity of the MPCP, the three SMG gauge couplings at the Planck
scale are predicted to be equal to the diagonal subgroup couplings correspond-
ing to the multiple point action parameters in a lattice gauge theory with the
gauge group $SMG^{N_{gen}}$. This prediction gives agreement with experiment to
within 10 \% for the non-Abelian couplings and 5\% for the U(1) gauge coup-
ling. In a more general context, the MPCP is proposed as a fundamental princi-
ple of Nature that can also explain other fine-tuning enigma in high energy
physics. It is argued that the MPCP implies having long range nonlocal inter-
actions which are identical between fields at all pairs of spacetime points.
Such interactions are allowed in a very general form of a reparameterization
invariant action. This phenomenologically unobjectionable form of nonlocality
would quite naturally be incorporated into our theory as constants of Nature.
