My own moral philosophy is a modified version of Kant's. First categorical imperative fails(relies on Kant's flawed epistemology) but Kant's second imperative(ends in themselves) is logically certain as it derives from the definition of personhood - whatever the essence of morality is, the person is the subject of moral duties. I propose this argument to personhood as an objective standard of morality.
1. A person is, by definition, and end in itself.
2. The self is a person because its rational will allows it to discover moral principles.
3. If the self is a person because of its rational will, all beings with rational will are persons.
4. Therefore, all beings with rational will are persons.
5. Therefore, all beings with rational will are ends in themselves.