Since Hume's Guillotine, philosophers have had more trouble defending the idea of ethics generally. Here is my answer for the principle of ethics and morality:
"What is the source of morality? Perhaps the following: •A long life is more valuable than a short life. •A short life can be forgiven. Using this principle, the only way to be blamed is if one lives a medium-size life. But such is ridiculous by any standard! Therefore, if we have a standard (longevity or forgiveness), we are forgiven. But there is no getting rid of the standard. Hence morality."
International Society for the Philosophy of Architecture » Ethics and Aesthetics of Architecture and the Environment