There are arguments to be made for both dynamic and static languages being good for moving quickly or accommodating change, often in the context of a startup. And it's true for both, except that a static language only lets you move quickly between correct programs.
I was thinking mostly about refactoring. If we overlook the ways we can circumvent the type system, a static language won't let you "just try something out" before it's ready: it has to be fully correct, or you nothing.
