How can we Have a Free Will?
'Free will' means that we ourselves do not know the outcome of a free choice until that choice, which is made by our unconscious, has reached consciousness and is thus remembered.
A free choice is random, because neurons are acting on molecular level. The preferences for the different options to be chosen from are determined by our structure as human beings, because structure can force matter into a certain way of action.
In a 'conscious choice', the preferences are predetermined by deliberations and may be close to zero or one. Thus, certain options will be definitely or will definitely not be chosen.
Overall, a free choice can be understood as a bifurcation, which develops as a Lyapunov instability in the complex structure of our brain.
What do we mean, when we say that we have free will? Typically, it is stated that in case of a free decision we could in principle have chosen another available option. Apparently, this statement cannot be proven. It would require that we redo the choosing under identical conditions, and thus also including at the same time and place, to see, if the outcome of the choosing could indeed have been different. Since we cannot travel back in time, this cannot be tested.
How can we nevertheless have the impression that we have a free will? It appears to be sufficient, if we ourselves do not know the option we choose until the very moment the choice is made. From the previous considerations of consciousness, this will obviously be the case. Since our unconscious is the active part, which does the choosing, our consciousness and thus our memory will only know the outcome of the choosing after the choice has been made. To have the impression that the decision is free, it is also required that we ourselves are not able to predict the outcome, for example, because we know how our personality and how we typically decide. Such a prediction is impossible, because our neurons link to the molecular scale, where only at most some 10 neurotransmitter molecules decide, if a neuron is firing or not (10 micro-molar calcium ions induce neuron firing * 20 nano-meter width of the synaptic cleft * 0.04 square micro-meter area of a synapse * 6.022 * 1023 molecules/mol = 5 molecules). Thus, the molecular randomness influences the decision, which thus has a random aspect.
At the same time we would claim that a decision is not completely random, but that we as person with our personality are causing the decision. We as structure have a determining influence on the molecules, as has been described for Bénard cells. Thus, on a structural level, we can determine the outcome to a certain degree. While it is not necessary that our structure defines each outcome of a decision exactly, it is in many cases fully sufficient that the probability of choice is defined. A certain degree of randomness always has to remain, because otherwise we would not have the impression of a free will.
This can be understood when regarding my visits to my favorite Italian restaurant. Since I am vegan, I have essentially two options on the menu, which I can choose, namely spaghetti aglio, olio e peperoncino or a nicely prepared colorful salad with a sauce vinaigrette. The spaghetti are a favorite of mine, so I will choose them in around 80% of my visits. That probability defines my personality without defining the outcome of a choice from the menu at an individual visit to the restaurant. At the same time, the probability for me to choose scaloppine is pretty exactly zero, because I am vegan. Thus, if we - induced by previous thoughts - have come to a definitive conclusion with respect to some essential choices in our life, the probabilities may very well be essentially zero, and we never choose this option, or essentially one, when we always will go for that option. These probabilities are then remembered and thus have entered consciousness. A conscious choice refers thus to a choice based on remembered probabilities, which can be essentially 0 or 1.
As on molecular level, also within our brain in the process of developing a decision, a Lyapunov instability is to be expected, since we are a complex system with many feedback loops. This means that the outcome of a choice, which is just a bifurcation, is initiated somewhere in our brain and then grows, until finally a state is reached, where our choice enters our consciousness and can thus be remembered. Here it also becomes obvious that the choice has to be attributed to us individually, because it is our personal structure, which laid the basis for the Lyapunov instability to develop in the way it did. To describe some detail of the process of making a choice, it may even be that partial choices are created at different points in our brain. For example, in a section which is building on our desires, it may well be that one partial choice is taken and developing with its Lyapunov time, while in a more rational section another partial choice originates, which is developing with another Lyaponov time. At a certain point, these partial choices have to lead to a final choice, which is again at the final point of decision influenced on the one hand by randomness, on the other hand by our personality, where the latter induces a certain consistency in our choices.