In 1983, the scientist Benjamin Libet made a startling discovery - all decisions are made by the physical brain around 1/3 of a second before we even become aware of them. This means that we do not have free will - this is not guesswork, not an assumption, but a scientifically proven fact.
The truth is the physical brain responds to input from the world and our own senses, and instantly starts to assess previous experience for an associated response pattern. This happens at colossal speed, far below the level of conscious awareness and so it’s likely what we consider to be the subconscious is just the physical brain process. There’s no value judgement being made, no ‘good’ or ‘bad’ course of action, just the brain simply activating a pattern that has been activated before in response to similar stimuli.
A stimulus - data input - received by the brain covers around 50 meters of neural pathways in the 1/3 of a second before it reaches awareness, during which time it goes through thousands upon thousands of tests that check for a continued pattern match. Some of the neurons are as small as 1 mm long and the data input, which is travelling at around 200 mph or more, is tested up to 1000 times at each end of the neuron. For reference, the brain has around 85-100 billion neurons.
Some people disbelieve the absence of free will, stating that they can easily change their mind about anything... And of course they can. But the decision to change their mind was formed by the brain up to 1/3 a second before they are consciously aware of it. Every thought we have has come from the brain’s continual monitoring process simply triggering a new ‘suitable’ response. Have you ever said something like: “What on earth did I say that for?” or: “I simply cannot believe I did that!” The reason is simple - the non-reasoning brain beat your conscious mind to the punch! Thoughts are slow and have to be considered. The brain has no such restriction. It just assess whether or not an input has a ‘registered response’ and if it has, activates it.