Tax cuts and revenues

There are still some shrill voices insisting that lowering tax rates increases revenue to the government based on increasing economic activity. To some of us this is a dubious claim, since the 'evidence' to support it is largely empirical and/or imaginative.
Follow this to it's logical end: If there is a formulaic relationship between lowered rates and increased revenue, as the rates approach zero, the revenue would approach infinity. Seems unlikely ? Maybe there's an optimum rate ? If so, why haven't we found it ?