: Re: Creating a logical framework for the concept of "decisional causality" I'm working on a science fiction universe in which time travel exists, in a very limited form, but it's useless, at least

@Holmes449

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Something irrevocable transpires.
I would say a decision is made when something irrevocable occurs. Words are spoken and heard, a button is pushed, a trigger is pulled, a letter is mailed, an email is sent.
Until then, it is only thoughts about a decision that might be made.
In Quantum Mechanics, we have this notion of a wave function, which describes all the possible ways that some set of sub-atomic particles can move and interact. However, some of these possible ways are mutually exclusive.
We also have the notion of wave function collapse, out of all these possible ways, if you try to measure some property of the particles, or any property of the particles, then instead of them being in all possible places with all kinds of energy, spin, momentum, etc, the wave function collapses and each particle is in a specific place, with a specifc potential energy, spin, momentum, etc.
Metaphorically speaking, decisions are like that. While the commander is mulling it over, he may mentally decide "Yes, I am going to launch at 5:00." But he doesn't tell anybody that, and this has no effect on the world, so in reality his wave function has not yet collapsed: He can change his mind and nobody would know, his earlier "decision" has not affected reality in any way, so it wasn't really a decision. An hour later something else occurs to him, and he tells his captain, "Launch now."
At that point something irrevocable has happened, he has changed the mind of the captain from "waiting for orders" to "orders received," and the captain is punching buttons and will launch. Even if the commander immediately regrets that order and rescinds it, that event cannot be undone with nobody knowing, the captain heard the launch order and his mind is forever changed by hearing it. Thus that decision was made. At that point, regrets and wanting to rescind that order would be thinking about making a decision; if it is voiced and the previous order rescinded, that was another decision, also heard by the captain, that cannot be undone.
Of course decisions at time X set one future in motion, a decision at time X+epsilon can set another future in motion.
But you have not really redefined cause and effect, the decisions are the causes of actions that change the world, however infinitesimally. And there will always be causes that have nothing to do with anybody's decision. One of the reasons we humans evolved is a ten mile wide asteroid crashed into the Earth and caused a nuclear winter that wiped out the dinosaurs, but our burrowing, scavenging ancestors survived. No decision of any sentient being on Earth caused an asteroid to crash into the Earth, and there are entirely plausible gravitational mechanics that allow random asteroids to be flung about in random directions within our solar system; and gravity is not "making decisions."

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