The past is determined. That much we know. What has already come to pass cannot be changed. The future however is a bit trickier. Is it pre-determined or completely uncertain/ ruled by free will?

The present in this case is the meeting of the two ... the point at which the uncertain and ill-defined transforms into the certain and defined. It is also the point at which the conscious mind resides and looks ahead to the future and recollects the past.

If we go by the idea that all of nature comes down to a logical interplay of set laws and principles of physics and chemistry, then the future is very much determined. We can calculate trajectories, predict reasonably accurately the weather some week or two in advance.

However when it comes to agency and conscious decision it gets harder to distinguish. How do I know that my sudden desire to buy an ice cream is of my own free will or pre-determined. Maybe I was deficient in calcium, it was a hot day, a new parlour had just opened that I heard about from my friend and I had just been given money and perhaps all of these factors combining simultaneously meant that my desire for Ice-cream was inevitable and always going to happen.

Perhaps the existence of the subconscious mind and the inability to be aware of all variables at all times are the only things separating us from the realisation that everything is a sum of pre-determined calculations and interactions. That free will may indeed be an illusion albeit a good one.