There are two main ideas about the origin of the time orientation of causation. The first is based in nature. The way nature works is that there’s a past, the past causes the present which causes the future, and so on. Nature has a direction of time, which is a direction of events causing other events. The second and opposite view is less obvious and fits in well with theoretical physics is that there is no time as there is in nature. The relation between cause and effect has a direction without any time order. Both of these views are wrong because they are incomplete.
What are causes? Nature clearly shows us that in its fundamental laws, it does not know about a time direction. From Newton, confirmed by fundamental physics, the universe doesn’t distinguish past from future. Physicists interpret laws and speak about the regularity of nature that are time reversal invariant. Physicists tend to have an interpretation of laws, which are not governing but rather observed regularities. What we call cause and we call effect are two terms of something that is related by something. We use cause for the one that comes first, and we use effect for the one that comes later, without any other substantial difference between cause and effect. Causation is this process that causes this other process. Time ordering between the cause and effect is set from before in time to after in time. This is a non-trivial issue which puzzles many physicists. Causation is used everywhere, but it’s not in the fundamental, elementary laws of physics.
The past is fixed because of traces, the future is open because the same macro-past can evolve into different macro-future. Humans, the agents, are the ones that have memory of the past, and can split the future and have the possibility of intervening. The direction of time uses the second law of thermodynamics and we are governed by this law. This permits the existence of traces so nature has a direction of time in its macroscopical description. Nature is macroscopically time-oriented, and microscopically non-time-oriented. This macroscopical orientation of the reversible all macroscopic phenomena, give rise to traces and to our possibility of splitting the future. We use this to read the causal relation between incomplete descriptions of nature.
Causation is also about intervention. Intervention requires something external. We assume that whatever the situation, we know what was in the past, and we don’t know what is the future. We are in a macroscopic, time-oriented description of the universe. The second law of thermodynamics, conversation of entropy, allows for traces and agency, and this is the basis that generates our description of the world in terms of intervention, which grounds the notion of causation. Causality is not a fundamental way to understand nature, but rather a ubiquitous way we have, as human agents for interacting with an approximate description of the world, where we actually can act in some moment, knowing the past and having the future open.
–Zahra Kanji