One of the core conundrums in metaphysics is the is-ought divide. What it says is that what a thing is cannot tell you what it ought to be. With sufficient reasoning, exploration, experimentation, and digestion, most things will either yield the secrets of what they are, or they will set the limits on what can and cannot be known about them. Science, logic, and rationalism are the powerful tools that we put to work to learn about the world around us, to determine what is, and what isn't. Facts, truth,.. all of these derive from epistemologies, the most solid and well-developed of which now power the nuts-and-bolts of our lives.
Morality is to ought what epistemology is to is. Except unlike the latter, one's morals are very much a personal matter [1]. What is right and wrong to you may be quite different from what your neighbor thinks is right and wrong (though it is learned, and it's a social creature besides). Some of the better-developed moral frameworks, like utilitarianism, pretend to offer the answers while really just hiding the uncertainty in the nitty details [2].
[1]Most debates, or at least the ones that people are want to get emotionally invested in, are moral ones at their core. You have your values, they have their values, and the two of you rationalize your feelings into arguments and pretend that your support for your own position derives from those arguments instead of the feelings that inspired their creation.
[2]In the case of utilitarianism, it's measuring utility; if we put pain and pleasure on opposite sides of the scales, how much of one is equal to how much of the other?
The very first observation about the dominant approach → is that it bridges the is-ought divide completely, without exception or complication. It reduces the question of morality to a question of epistemology.
If we accept causality, then it follows that (aside from Ur-beginnings) everything has a cause or set of causes [3] that together form the reason for a thing's existing the way it does.
[3]You may want to draw some kind of exception for randomness →. The luck of the draw is, after all, often used to justify uncomfortable results, and a roll of the dice is often used to make decisions that are free from external influence. Note however that in these cases, randomness does not eliminate causes, it merely obfuscates them. Specifically, it elevates small causal fluxuations into large ones.
Consider Chesterton's fence ⬈ (do read; it's short). If you pass through a gate connecting two fields on a farm, you should leave the gate in the configuration that you found it. You may not know why the gate is open or closed, but you can be reasonably certain that the farmer left it that way for a reason. In this specific case, the question "should I change the configuration of the gate?" is answered "no". Even though you don't know the reason, the fact that you believe it has a reason is enough to derive your answer. The question of ought is is; the dominant approach is the correct one.
What applies to farmers' fences may not apply everywhere. If we were to discover that the farm was abandoned (i.e. there is no farmer), the reasoning appears to fail. There's something particular about the fact that the fence was given purpose that makes the dominant approach correct. As noted above, everything exists for a reason, so merely having a reason doesn't appear to be enough.
A useful heuristic for whether the dominant approach may be appropriate: the state is the way it ought to be if it has been put there with purpose.
If you personally put something in order to give it purpose, it follows that as far as you are concerned, the thing is the way it ought to be. Assuming that other people are just like you is a surprisingly good approximation of what other people are like, and so it follows that if some person gave it purpose, your first approximation is that it is the way it ought to be according to them, and since they are like you, according to you too. The gap between is and ought here derives from the differences between you and whomever you think is responsible. Or more specifically, the differences in the implementation [4] of your various purposes.
[4]I stress 'implementation' here, because you and another might have differing purposes for a thing and nevertheless configure it to be in the same state, in which case it is the way it ought to be.
Another heuristic for whether the dominant approach is appropriate: in order for the state to not be the way it ought to be, you personally must have given it a purpose that requires it to not be the way that it is.
There is, of course, no reason why this must be limited to humans. Dogs can give purpose to the world around them [5], and this logic is not bound even to mammals. Any animals that has a nest or burrow can reasonably be said to have granted purpose to the configuration of the corner of reality they call home.
[5]My stick!
What about beyond the limits of life? Consider a lake. It exists where and when it does for a reason: the shape of the earth beneath it, the topology of the land around it, the conditions of the weather and climate that bring it rain, its in-flows and out-flows, etc. Is the lake the way it ought to be?
Well, what way ought it to be if not the way that it is? Once you answer that question, you've given the lake a purpose that contradicts its reality, and the is-ought divide appears. If you don't answer the question (or in the event that you find the question to have no answer), it follows that we are unable to reject the dominant approach, the proposition that it is the way it ought to be. The case where there is no answer to the question can be thought of as the case of the inevitable.
Another heuristic is that if there is no other way for a thing to be, we can apply the dominant approach.
You may shake your fist at the stars, cursing them for what they are, but if you cannot change them, you have no choice other than to accept them. And once you have accepted them, your purpose for them no longer differs from what they are, and the dominant approach once more asserts itself.
Lakes may not quite fall into this category; building dams and draining swamps are two ways that the state of the world fails to be inevitable. But these limits are limits of our power, and beyond our puny reach the inevitable can be declared. Only Gods can move stars, and if a God put it there for a reason, it must be the way it ought to be.
So far I have only been considering the is-ought divide within the context of configuration spaces. Let us not forget that time is a part of the equation.
Our most startling conclusion comes from applying the third heuristic to time. That which cannot be changed is how it ought to be, and the past cannot be changed. Therefore we can conclude that the dominant approach applies to the entire past, including up to a small fraction of a second behind the present. Does this mean that things that just happened are the the way they ought to be? Not exactly [6]. A fine parsing shows that the fact that they happened is how it ought to be, but the resulting state, if it can still be changed/undone, does not necessarily fall under this umbrella. In general, the more recent a thing is, the easier it is to undo, meaning that it is as events 'sit' and 'settle' that their state transitions into its purposeful state.
[6]This generally agrees with the observation that pretending a thing didn't happen doesn't actually make it so that it didn't happen. The dog may kick grass over their shit, but the shit is still there beneath the grass [6-1].
[6-1]Alternatively, the winners may write history, but their history is still written in the blood of their enemies.
Another interesting result can be gained by applying the third heuristic with an eye towards the future. Your power to give purpose to a thing is roughly equivalent to your ability to influence that thing. The sphere of your influence is a cone expanding as it goes into the future, and now we see that things that are not in that cone are the way they ought to be, because you cannot change them. Even though they lie in the future, they are effectively inevitable w.r.t. your point of view.
We established with our second heuristic that the is-ought divide can only appear in scenarios where you personally have given a thing a purpose that's contradicted by its existence. We established in the third heuristic that if you cannot influence a thing, then it is must be the way it ought to be. Between these two, we get a fairly rigorous definition of acceptance: not giving contradictory purposes to things you cannot influence. I'll go ahead and suggest that you should always practice acceptance [7]; as far as I can tell, not doing so simply invites anguish in exchange for nothing.
[7]This includes accepting everything unpleasant that's ever happened in the past; this is not as emotionally easy a position to take as you might suspect.
Dominant theory allows one to take this one step further, to what I call radical acceptance: not giving contradictory purposes to even the things that you can influence. Note that this does not mean that you shouldn't do anything; you can still give purpose to the world, and you are welcome to change the world in any way that's within your capacity. Dominant theory comes along afterwards and justifies your actions as being 'correct' by the virtue that they occurred.