I hope to post something on William Whewell's ethics. To understand Whewell's ethics, however, one must first understand his epistemology, which he developed in doing his groundbreaking work in the history and philosophy of science. The heart of this epistemology is the view that all human cognition consists of two parts or aspects, which Whewell calls Thing and Thought, Observation and Reflection, or (most often) Fact and Conception. (Strictly speaking, Whewell distinguishes all these three: Observation, for instance, is an action, and Facts are assertions about Things; but they are all closely related.) When he is talking about the most general and stable Conceptions, he calls them General Relations or (when they are considered simply in themselves) Ideas. Examples of Ideas are Space, Time, Number, Resemblance, and Cause. We use these Ideas to connect Facts by necessary consequences; this is called reasoning. In reasoning we assume certain Fundamental Principles with regard to these General Relations; these are sometimes called Axioms or Maxims, as in the Axioms of Geometry.
Scientific thought is the observation of the external world in light of the General Relations; and in this observation we often comes to recognize that a group of Facts or objects correspond to a general Law. This is a Law of Nature, and on the basis of Laws of Nature we can predict that some things will certainly happen, and others probably will happen. When we separate Laws of Nature from the Facts that conform to them, they are called Theories.
This basic pattern extends into moral science as well as physical sciences. Just as there are Laws of Nature to which Facts in the external world conform, there are Laws of Human Action. However, the precise relation between Law and Fact is somewhat different. In physical sciences we ascend from Fact to Law, and try to find the Law that best fits the Facts; this is a matter of speculative reason. In moral sciences, however, we descend from Law to Fact, and try to conform the Facts as best we may to the Law; this is a matter of practical reason. Since both, however, operate on the same principles, the principles and inferences of practical reason can be unfolded into a speculative system.
You can read a passage from Whewell on this subject here. I hope to get to Whewell's ethics soon.