I agree with you that very few behavioral norms are invented from scratch, and that the more complex ones pretty much never are, and that they must therefore be propagated culturally.
That said, your analogy is actually a good one, in that I have the same objection to the analogy that I had to the original.
Unlike you, I suspect that there's quite a lot of in between: some people use integrated-circuit computers, some people (often the same people) use pen and paper, some people use a method of successive approximation, some people count on their fingers. It depends on the people and it depends on the kind of calculation they are doing and it depends on the context in which they're doing it; I might open an excel spreadsheet to calculate 15% of a number if I'm sitting in front of my computer, I might calculate it as "a tenth plus half of a rounded-up tenth" if I'm working out a tip at a restaurant, I might solve it with pencil and paper if it's the tenth in a series of arithmetic problems I'm solving on a neuropsych examination.
When you say "most people use some integrated-circuit computing machine, or nothing" you end up excluding a wide range of actual human behavior in the real world.
Analogously, I think that when you talk about the vast excluded middle between "morality" and "pecking order" you exclude a similarly wide range of actual human behavior in the real world.
When that range is "approximated as just having two choices" something important is lost. If you have some specific analytical goal in mind, perhaps the approximation is good enough for that goal... I'm afraid I've lost track of what your goal might be, here. But in general, I don't accept it as a good-enough approximation; the excluded middle seems worthy of consideration.
On January 11, 2007, I timidly whispered to myself: "There is no God."
And with that, all my Christian dreams and hopes and purposes and moral systems came crashing down.
I wrote a defiant email to the host of an atheist radio show I'd been listening to:
I was not okay with the truth. I had been taught that meaning and morality and hope depended on God. If God didn't exist, then life was meaningless.
My tongue felt like cardboard for a week.
But when I pulled my head out of the sand, I noticed that millions of people were living lives of incredible meaning and morality and hope without gods. The only thing I had 'lost' was a lie, anyway.
This crisis taught me a lesson: that I could be okay with the truth.
When I realized that I am not an Unmoved Mover of my own actions, I was not much disturbed. I realized that 'moral responsibility' still mattered, because people still had reasons to condemn, praise, punish, and reward certain actions in others. And I realized that I could still deliberate about which actions were likely to achieve my goals, and that this deliberation would affect my actions. Apples didn't stop falling from trees when Einstein's equations replaced Newton's, and humans didn't stop making conscious choices that have consequences when we discovered that we are fully part of nature.
I didn't freak out when I gave up moral absolutism, either. I had learned to be okay with the truth. Whatever is meant by 'morality', it remains the case that agents have reasons to praise and condemn certain desires and actions in other agents, and that there are more reasons to praise and condemn some actions than others.
I've gone through massive reversals in my metaethics twice now, and guess what? At no time did I spontaneously acquire the urge to rape people. At no time did I stop caring about the impoverished. At no time did I want to steal from the elderly. At no time did people stop having reasons to praise or condemn certain desires and actions of mine, and at no time did I stop having reasons to praise or condemn the desires and actions of others.
We humans have a tendency to 'freak out' when our model of the world changes drastically. But we get over it.
The love a mother has for her child does not disappear when we explain the brain processes that instantiate that love. Explaining something is not explaining it away. Showing that love and happiness and moral properties are made of atoms does not mean they are just atoms. They are also love and happiness and moral properties. Water was still water after we discovered which particular atoms it was made of.
When you understand this, you need not feel the threat of nihilism as science marches on. Instead, you can jump with excitement as science locates everything we care about in the natural world and tells us how it works. Along the way, you can take joy in the merely real.
Whenever you 'lose' something as a result of getting closer to the truth, you've only lost a lie. You can face reality, even the truth about morality.
- Eugene Gendlin