In Part 3, we examined why many contemporary Protestants have something of a bad conscience when it comes to natural law. But, of course, the blame for this cannot be laid fully upon Karl Barth. Even a hint of a fuller explanation has to address intellectual currents that begin to gather momentum in the so-called Enlightenment. One popular explanation within the academic mainstream for the demise of the natural-law tradition in modern Protestant theology attributes it to a form of implosion. And this is what I want to take up here.