Here's what I've got:
What strikes me as a tautology is that the placement of moral value is dependent on the preferences of the placer. When you establish empirically that the placer and his preferences have been molded by the history of Earth, you realize that humanity has a fundamental, inbred desire to aid through action both the personal and general perpetuation of humans and human-like things.
We also have, through simple action, grown general modi operandi -- the justifications for which are, at their very most refined, contingent purely on the empirical data we have managed to accumulate -- for satisfying our fundamental human biases.
Some of these policies, like rogue tree branches, take needlessly indirect paths to light or turn uselessly back around on us. These policies are "evils" to diagnose, correct, and in severe cases, amputate. This process of diagnosis is morality, and this process of correction is practical agency.
Thoughts?
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While cogent, your scrutiny of ethical syllogisms is subject to strong critique in the form of Cartesian rationalism and possibly and more narrowly the application of solipsism brings your claims of metacognitive development into question. That said if we defer to the use of Wittgensteinian truth-tables to analyze the possible arrangements of logical possibilities from said postulates it might verily be revealed, should we discard the epistemological objections, that such propositions are tautologous after all.