GMpoison your approach is a logical one. However, you cannot escape the apriori. In matters of the intellect we can follow our reason as far as it will take us without regard to any other consideration but reason can never answer all questions. There will always be a need to make apriori assumptions. Even the refusal to make a choice is a choice and all choices have consequences and shape your interaction with the world. A helpful essay that illustrates the limitation of reasons and science is:
The Limits of ScienceIn your example above you do not define what good is and consequentially what constitutes evil. Without a definition you have no way of actually applying your worldview to reality.
For example one theist view of evil is the following.
http://www.shamash.org/lists/scj-faq/HTML/faq/12-20.htmlAll the evil in the world is either:
1) Made by man and permitted by God because the evil is not worse than reducing all of humankind to mindless automata.
2) An effect of nature that God allowed because the alternative would be to prove His existence by intervention, thereby eliminating free will.
3) Something that only seems to be evil from our limited perspective, but wouldn't be judged evil if we have all the facts. These often become clear with sufficient hindsight, although they often do not, as well.
An common atheist perspective is that there is no such such thing as good or evil there is only "i like" and "i don't like" and even that can be reduced to simple biological imperatives which in turn are nothing more then chemical reactions in the brain without underlying meaning or significance.
These views when applied to life will take one to very different conclusion regarding what is moral, what is acceptable behavior, and how one should structure ones life.
I'm not quite sure what good and bad or right or wrong have to do with anything and why I can't apply my worldview to my reality without a definition of either?