Ethics as a discipline can be defined as any theory regarding preferable human behaviour that is universal, objective, consistent – and binding. Where does this come from?
Page 32: If you want to live, it is universally preferable that you refrain from eating a handful of arsenic." it is universally preferable that your theories be both internally consistent and empirically verifiable. “Universally preferable,” then, translates to “objectively required,” but we will retain the word “preferable” to differentiate between optional human absolutes and non-optional physical absolutes such as gravity.
One adopts a goal, then a causal relationship exists between the goal and the means of achieving it. Sometimes the means is unique, sometimes many means are equally preferable. Why talk about preference or preferability at all?
What does that mean? How can an ethical theory contradict empirical evidence, since it is not a factual claim? Feasibility? What are near-universal preferences?
Thus in ethics, just as in science, mathematics, engineering and all other disciplines that compare theories to reality, valid theories must be both logically consistent and empirically verifiable.