I wouldn't dream of being so rude and pushing ahead when you haven't even had the chance to give your position of why any argument basing morality on nature must be fallacious and circular.
Actually I didn't move any goal posts. What has happened is you haven't given your basic position and defended it. All the rest followed from this; like me assuming (quite appropriately when you used terms like the 'naturalistic fallacy') you were just giving the usual modern position, showing that intelligent people have disagreed with this and hence you need to state your position; like me exploring a position on nature that does escape these moderns assumptions and sanctions. None of this is moving the goalposts. It is just a game of a penalties while we wait for the other team to arrive. At the moment there is just the mascot giving the team motto, but without any of the players to defend it.
And by the way, it is clear you are now trying to get me to attack the position you won't defend and hence trying to avoid defending the whole reason for our discussion. If that isn't moving the goalposts, indeed directly switching them around, then what is?
It wouldn't be rude to provide me a canvas to work with to explain my views so that they can be understood more easily.
To do this, I must have a specific logical argument to work with. Then I can demonstrate exactly how that argument is employing circular reasoning Take your assumpetions inhernent in your claims against my final cause of the heart for example. You are employing unchallenged assumptions about reality based on an human-centric perspective of reality.
All natural law proponents I have encountered fall prey to this same problem, and those unchallenged assumptions about reality lead to circular reasoning, but in a very subtle, yet meaningful way.
In order to see the logical flaws, you must first look at your argument from a
totally different perspective (but one still
firmly grounded in reality). My point about the final cause of the heart is one that employs a fundamentally different perspective from what you are using, but both perspectives are still firmly grounded in reality. Mine incorporates a far larger time frame, though, and a much,
much wider scope. I understand the inherent difficulty in understanding that perspective, though, most people have difficulty expanding their views in such a way because doing so immediately forces them to realize the meaninglessness of their own individual existence.
When that perspective is applied to the same reasoning, though, the result of said reasoning changes dramatically. Therein lies my overall position on "nature". The perspective from which someone views reality
defines their
understanding of reality in a way that it causes many unchallenged assumptions which lead to circular reasoning when one argues that what is natural is good.
From the larger scope perspective, "good" and beneficial are determined in dramatically different ways than it is in the smaller scope perspective. What is good for the individual in the smaller scope perspective is not necessarily good for the whole in the larger scope perspective. What is a final cause in a smaller-scope perspective is actually a stepping stone along the way to the final cause in the larger scope perspective.
Let's use Aristotle's seed example to explain this a bit. Aristotle would argue that the final cause of a seed is to become an adult plant. The seedling stage of development would simply be a step along the way to this final cause. From the larger-scope perspective, though, the final cause of the plant is taken into account, hell even the final cause of the
species is accounted for in the larger-scope perspective I am employing.
Because of the limited scope of Aristotle's perspective, he had unchallenged (even unknown) assumptions about reality that went into his analysis. The way that one determines natural law, though, is
entirely dependent upon the results of those unchallenged and unknown assumptions. That's where the circular reasoning comes into play. You keep assuming that circular reasoning is always an
obvious mistake (which is a
great example of an unchallenged assumption based on perspective, by the way), when circular reasoning can often be quite subtle.
On top of that, for Aristotle and most long dead philosophers such assumptions are completely understandable, if not entirely unavoidable. When the Earth is believed to be the
only planet in the universe (and the
center of the universe, no less) and the total time it has existed is believed to be only a few thousand years, it's almost impossible to employ a perspective like the one I am employing.
But with today's knowledge, such a perspective
is possible (although very rarely employed in this manner). And when discussing concepts such as nature, such a perspective is of
absolute importance. Anything less requires one to ignore more than 99.99999999% of all reality. In that choice to ignore lies the circular reasoning in modern argument, too.
But once that wider-scoped perspective can be achieved, we could actually
begin to start discussing my own personal views on nature and natural laws and how morality, by necessity, requires a smaller-scoped perspective than what is required for any discussion on nature.
Now, if you want to see the above explanation put into action, present a specific logical argument about how something is moral simply because it is "natural". I will then give a very detailed demonstration of how you have employed unchallenged assumptions in a circular manner.
The ultimate question you have to ask yourself about any given premise you could use is "Why do I think this?" If the answer is along the lines of "Well, because it is" then you are probably employing circular reasoning of the type I describe.