who came up with this theory?
Immanuel Kant.
Kantian ethics
Kantian ethics refers to a deontological ethical theory developed by German philosopher Immanuel Kant that is based on the notion that: "It is impossible to think of anything at all in the world, or indeed even beyond it, that could be considered good without limitation except a good will." 
which of the following is also known as the kantian tradition in ethics Kantian ethics refers to a deontological ethical theory that is based on the notion that: "It is impossible to think of anything at all in the world, or indeed even beyond it, that could be considered good without limitation except a good will." can you outline it for me? As part of the Enlightenment tradition, the  ethical theory on the belief that reason should be used to determine how people ought to act. No attempts have been made to prescribe specific action, but its instructed that reason should be used to determine how to behave.
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Kantian ethics [SEP] Introduction
Kantian ethics refers to a deontological ethical theory developed by German philosopher Immanuel Kant that is based on the notion that: "It is impossible to think of anything at all in the world, or indeed even beyond it, that could be considered good without limitation except a good will." The theory was developed as a result of Enlightenment rationalism, stating that an action can only be good if its maxim—the principle behind it—is duty to the moral law, and arises from a sense of duty in the actor. Central to Kant's construction of the moral law is the categorical imperative, which acts on all people, regardless of their interests or desires.