What do I mean by "morality isn't logical"? I mean in the same sense that mathematics is logical but literary criticism isn't: the "reasoning" we use to think about morality doesn't resemble logical reasoning. All systems of logic, that I'm aware of, have a concept of proof and a method of verifying with high degree of certainty whether an argument constitutes a proof. As long as the logic is consistent (and we have good reason to think that many of them are), once we verify a proof we can accept its conclusion without worrying that there may be another proof that makes the opposite conclusion. With morality though, we have no such method, and people all the time make moral arguments that can be reversed or called into question by other moral arguments. (Edit: For an example of this, see these posts.)
Without being a system of logic, moral philosophical reasoning likely (or at least plausibly) doesn't have any of the nice properties that a well-constructed system of logic would have, for example, consistency, validity, soundness, or even the more basic property that considering arguments in a different order, or in a different mood, won't cause a person to accept an entirely different set of conclusions. For all we know, somebody trying to reason about a moral concept like "fairness" may just be taking a random walk as they move from one conclusion to another based on moral arguments they encounter or think up.
In a recent post, Eliezer said "morality is logic", by which he seems to mean... well, I'm still not exactly sure what, but one interpretation is that a person's cognition about morality can be described as an algorithm, and that algorithm can be studied using logical reasoning. (Which of course is true, but in that sense both math and literary criticism as well as every other subject of human study would be logic.) In any case, I don't think Eliezer is explicitly claiming that an algorithm-for-thinking-about-morality constitutes an algorithm-for-doing-logic, but I worry that the characterization of "morality is logic" may cause some connotations of "logic" to be inappropriately sneaked into "morality". For example Eliezer seems to (at least at one point) assume that considering moral arguments in a different order won't cause a human to accept an entirely different set of conclusions, and maybe this is why. To fight this potential sneaking of connotations, I suggest that when you see the phrase "morality is logic", remind yourself that morality isn't logical.
Thanks for taking the time to read and respond to the article, and for the critique; you are correct in that I am not well-versed in Greek philosophy. With that being said, allow me to try to expand my framework to explain what I'm trying to get at:
Example: "I think that heat is transferred between two objects via some sort of matter that I will call 'phlogiston'. If my hypothesis is true, than an object will lose mass as it cools down." 10 days later: "I have weighed an object when it was hot, and I weighed it when it was cold. The object did not lose any mass. Therefore, my hypothesis is wrong".
In logical terms: Let's call the Theory of Phlogiston "A", and let's call the act of measuring a loss of mass with a loss of heat "C".
If A, then C.
Physical evidence is obtained
If Not C, then Not A.
Essentially, the scientific method involves the creation of a hypothesis "A", and a logical consequence of that hypothesis, "If A then C". Then physical evidence is presented in favor of, or against "C". If C is disproven, then A is disproven.
This is what I mean when I say that hypotheses are "axioms", and physical experiments are "conclusions".
"No proofs, just conversations". In the framework that I'm working in, every single statement is either a premise or a conclusion. In addition, every single statement is either a "truth" (that we are to believe immediately), a "proposition" (that we are to entertain the logical implications of), or part of a "hypothesis/implication" pair (that we are suppose to believe with a level of skepticism until an experiment verifies it or disproves it). I believe that every single statement that has ever been made in any field of study falls into one of those 3 categories, and I'm saying that we need to discuss which category we need to place statements that are in the field of ethics.
In the field of philosophy, from my limited knowledge, I think that these discussions lead to conclusions that we need to believe as "truth", whether or not they are supported by evidence (i.e. John Rawl's "Original Position").
But there is a mini-premise, inference and mini-conclusion inside every "hypothesis-implication pair".