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One often hears that the strong $CP$ problem is the one problem which cannotbe solved by anthropic reasoning. We argue that this is not so. Due tononperturbative dynamics, states with a different $CP$ violating paramenter$\theta$ acquire different vacuum energies after the QCD phase transition.These add to the total variation of the cosmological constant in the putativelandscape of Universes. An interesting possibility arises when the cosmologicalconstant is mostly cancelled by the membrane nucleation mechanism. If the stepsize in the resulting discretuum of cosmological constants, $\Delta \Lambda$,is in the interval $({\rm meV})^4 < \Delta \Lambda < (100 \, {\rm MeV})^4$, thecancellation of vacuum energy can be assisted by the scanning of $\theta$. For$({\rm meV})^4 < \Delta \Lambda < ({\rm keV})^4$ this yields $\theta <10^{-10}$, meeting the observational limits. This scenario opens up 24 ordersof magnitude of acceptable parameter space for $\Delta \Lambda$ compared tomembrane nucleation acting alone. In such a Universe one may not need a lightaxion to solve the strong $CP$ problem.

Landscaping the Strong CP Problem