Patrick Logan explains why you really want a dynamic language:

Lists, maps, arrays, even self-referencing structures can all be entered end edited in a command loop or workspace using a very simple (i.e. few characters) syntax. There are also the mundane (now that Java brought them to the masses) aspects of these languages like garbage collection and array bounds checking

Productivity is greatly enhanced when you can explore the bounds of a problem easily. Most of the static language crowd still doesn't get this