I think that Dr. King used the notion of "direct action" to bring out the immediate need for action. Part of what makes Dr. King's writing so powerful is that there is a "fierce urgency of now." Dr. King understands that his writing and the approach he takes to it is not only going to speak to people of color, but also moderate to liberal White Americans who could be convinced that the Civil Rights Movement was as much an ethical or moral imperative than anything else. In making this case so appealing to this audience, Dr. King has to argue that there was no other path that could be pursued other than "direct action." It is this element that makes the case such a human one for Dr. King. In articulating a condition where some level of direct action is needed at this particular moment, Dr. King makes the argument that the situation of intense racism and discrimination in Birmingham necessitates "direct action." In trying to bring out the need and urgency for action, Dr. King's argument helps to illuminate the moral and ethical crisis that he feels is such an integral part of the movement in Birmingham.