Final answer:
According to Kant, an action has moral worth if it is done from a sense of duty, which is part of his deontological ethics and the principle of the categorical imperative.
Step-by-step explanation:
According to Immanuel Kant, an action has moral worth if it is done from a sense of duty. For Kant, the only thing that has unconditional value is the good will, which represents the decision to carry out our moral duties because it is our duty, without any influence from the prospects of achieving beneficial outcomes or from our feelings about the action. This concept is central to Kant's deontological ethics, which is based on the principle that actions are morally right in virtue of their motives, which must derive from our sense of duty.
Kant's notion of 'acting from duty' stems from the belief that humans, as rational beings, have the capacity to act in accordance to categorical imperative, a universal moral law formulated by the maxim: 'Act only according to that maxim whereby you can, at the same time, will that it should become a universal law'. This reflects the idea that moral actions should be universalizable, meaning that one should act in a way that they would want all others to act in similar circumstances.