We might be tempted to think that the motivation that makes an action good is having a positive goal--to make people happy, or to provide some benefit.
Someone with a good will, who is genuinely committed to duty for its own sake, might simply fail to encounter any significant temptation that would reveal the lack of strength to follow through with that commitment. Hence no imperative is valid for the Divine Will, nor indeed for any will figured to be Holy.
Guyer, by contrast, sees an argument for freedom as an end in itself Guyer In the first chapter of his Utilitarianism, Mill implies that the Universal Law formulation of the Categorical Imperative could only sensibly be interpreted as a test of the consequences of universal adoption of a maxim.
When from these general features we pass to a more minute examination of the philosophic system, there is a marked distinction between the Intellectual, or theoretic part, and the Moral, or practical part.
To that extent at least, then, anything dignified as human willing is subject to rational requirements. Then Kant analyzes the understanding, the faculty that applies concepts to sensory experience. Moral requirements, instead, are rational principles that tell us what we have overriding reason to do.
Further, a satisfying answer to the question of what one ought to do would have to take into account any political and religious requirements there are. Kant is the primary proponent in history of what is called deontological ethics. That, she argues, would imply that there would be no reason to conform to them.
Rather than commanding specific actions, it must express the principle that actions should be undertaken with pure motives, without consideration of consequences, and out of pure reverence for the law.