I have three questions:
1. Morality of an action is determined by the motives of duty.
2. Morality based on Good Will (unqualifiably good).
3. Rationality lead to unqualifiably good.
There are three key terms in the question(s) we have before us- "motives of duty", "Good Will" and "Rationality". All the three terms are interrelated when it comes to what determines rightwrong action in Kant. To understand the terms very well will, therefore, require an introductory background in Kant's ethical or moral theory.
You may be aware that there are several theories of right and wrong (e.g. Utilitarianism, egoism, religious norms, etc.). But according to Kant, the right action is a kind of 'command' or 'rule' that we ought to obey regardless of the consequences of such command. This is what he refers to as 'Categorical imperatives'- absolute laws or commands we ought to obey irrespective of their outcome. If a person acts according to this principle, he acts rationally partly because the action springs from good will, which reason identifies with one's duty or obligation.
Kant is also aware that it is possible for moral agents to decide to avoid errors and to safe life and/or properties sometimes. For instance, if a suspected murderer holding a gun in her/his hand is looking diligently for your best friend, you might not want to tell your friend's whereabouts to this guy even if you have information about your friend. Here, you're acting according to your own interest. In other ...
The basis of Kant's moral theory is assessed.