look, here's where you are indeed being facetious ;-). i think its because you believe, as in mathematics, that providing an alternate scenario, however unlikely/unimaginable, disproves your opponent's thesis.
but the reality is that in order to come up with rules and theories in ethics, we have to start somewhere (quite true in mathematical deductive logic too, really. euclid's fifth axiom has been called to question, but is still in use. similarly, intuitionists and others question the use of the axiom of choice). as you point out, that somewhere can be based on the smallest, most agreed upon, consensus of the people. or, as i mentioned, it can be derived from some biologically self-evident ideas (self-interest) or logical ideas (self-preservation, to speak loosely). i personally believe the latter is, strictly speaking, infeasible.
if our starting point happens to be from common notions it does not follow that our final positions are or should be ill-reasoned/ad-hoc. hence my real world examples. if indeed you are going to choose the non-comatose person because he is thinner, you fall outside the consensus... i could probably provide other example scenarios involving thin people where you may go against this rule, thus exposing an inconsistency in your position (or perhaps not -- its possible, theoretically, for you to build an airtight ethics out of such crazy criteria ;-)), but need we go there?
> --How would I decide? Collaborative decision making among the affected
> parties. I see no need to impose arbitrary moral assumptions on the
> participants (e.g., suffering is bad, conscious life is more valuable
> than nonconscious life, etc.).
we are not imposing moral assumptions. they emerge from the consensus. if 1 million people participate in a referendum to choose the comatose-vs-ill issue, it is not only required that they provide a yes-no vote, but also explain how they derive that vote. the latter requirement helps maintain consistency and aids in abstraction. surely, you do not believe that instant polling will yield the best answers in all cases?
> I think your careful response highlights my point in this thread:
> abstract moral principles cannot provide practical guidance about
> behavior in real life contexts, because real social life is far more
> interesting and complex than philosophers appreciate (I think of
> Wittgenstein: "back to rough ground"--the icy perfection of
> philosophers' scenarios is a fundamental distraction from the solutions
> to the practical problems we face).
but that is my point! choosing how we dispense limited services/resources is a real and practical problem. the philosophy is not so much a philosophy as a theory of ethics that helps formalize the thought and application. i agree with you about the complexity and need for care. but the abstraction is not a starting point arrived at in detachment. it is the result of exercising such care. no doubt it will be incomplete and will need to be fine tuned for each use. no different from the system of laws, yes?
> I know I've pestered you in this thread; I was trying to see if there is
> some logically consistent, universal principle that guided your
> actions. In your last paragraph, you make it clear that you are not a
> principled utilitarian (to which I say, Huzzah!): your reasoning is
> contingent, based on the inherent complexities of specific social
> situations.
yes, i am not a utilitarian. and i agree with you that one should not start from abstract principles. however, in this space, the principles are abstracted from the particular reasoning in a two-way feedback loop. after all, one cannot even start reasoning if one doesn't have something to bootstrap from (could just be plain emotional consensus, but the feedback mechanism can help correct emotional excess).
IMHO, this is getting more abstract, actually than necessary. in the real world, when we decide the question of comatose-vs-ill we reason in ways that assume the consensus. given such consensus rules/goals/values, in the real world (not the miles jackson fashionably thin world ;-)), singer shows that there is nothing in those rules to exclude their application to animals. to really make your case, you have to provide some system where attention to avoidance of suffering, consciousness (or any of the other values that we are assuming in this debate) are not values and part of the consensus that drives decisions and actions, not provide improbable scenarios!
--ravi