I expect that your concern doesn’t really have to do with causality and is already there in “probability is in the mind.” But I’m going to argue that causality is in the mind.
Causality is in the model. Let’s say that we work with billiard ball physics of gas. Since the model is reversible, it has no arrow of time (or maybe it has both arrows of time). In fact, I might say that the “real thing” is a timeless view and choosing to slice by time is a modeling choice. If we know that the gas is concentrated in half of the room at time zero (a probability distribution over microstates), we have a forward arrow of causality. But talking about what we know is about the mind. This assumption leads to a backwards arrow during negative time, but that’s OK, because the model is wrong for negative time: we put the gas in half of the room, violating the model.
Thermodynamics is in the mind. The causality of thermodynamics is in the mind. Thermodynamics is a good model because it is about things we can really measure, not microstates that we cannot; it is a good model because it matches our ignorance, which is in our minds.
An ideal reasoner (eg, AIXI) would not use thermodynamics, but work directly with microstates, but this is not practical if the reasoner is in the world. But AIXI does have belief about the underlying model of the universe, which can be wrong.
I expect that your concern doesn’t really have to do with causality and is already there in “probability is in the mind.” But I’m going to argue that causality is in the mind.
Causality is in the model. Let’s say that we work with billiard ball physics of gas. Since the model is reversible, it has no arrow of time (or maybe it has both arrows of time). In fact, I might say that the “real thing” is a timeless view and choosing to slice by time is a modeling choice. If we know that the gas is concentrated in half of the room at time zero (a probability distribution over microstates), we have a forward arrow of causality. But talking about what we know is about the mind. This assumption leads to a backwards arrow during negative time, but that’s OK, because the model is wrong for negative time: we put the gas in half of the room, violating the model.
Thermodynamics is in the mind. The causality of thermodynamics is in the mind. Thermodynamics is a good model because it is about things we can really measure, not microstates that we cannot; it is a good model because it matches our ignorance, which is in our minds.
An ideal reasoner (eg, AIXI) would not use thermodynamics, but work directly with microstates, but this is not practical if the reasoner is in the world. But AIXI does have belief about the underlying model of the universe, which can be wrong.