Even if philosophers and divine scholars give different reasons for free will of the human being, here we will take a short cut and give the clearest reason given by the supporters of free will and this is the ‘universal’ or ‘collective’ conscience of human beings.
That is, no matter what we deny, we cannot deny this reality that in all human societies, including both the worshippers of God and the materialists, East and West, ancient and modern, wealthy and poor, developed or undeveloped, of whatever culture, all without exception, agree that a law should rule human beings and that human beings are responsible before the law and people who disobey the law must be punished.
In other words, the rule of law, the responsibility of individuals before it and the punishment of those who disobey the law are things which all intelligent people agree with and it was only savage, primitive tribes who did not officially recognize these three things.
The fact that we explain this as the general conscience of human beings of the world is the clearest proof of the existence of free will in human beings and the fact that they have free choice. How can it be accepted that a human being be obliged in his or her actions and that he or she have no freedom of choice but he or she is responsible before the law? And that when a law is broken, that person must be tried and asked why he or she did this or that or did not do this or that.
And if proven guilty, that person is sent to prison or even, depending upon the crime, executed, this is exactly as if we were to punish stones which slide down a mountain causing a landslide on a mountain road which results in the death of one or more human beings.
It is true that a human being differs from a stone, but if we deny free will and choice in a human being, this external difference between them will not be relevant and both will be the victims of fate. A stone, following the law of gravity, falls upon the roadside and a human being who murders another, is the victim of another factor of fate.
Thus, the logic of those who believe in predetermination allows for no distinction to be made between a stone and a human being from the point of view of result, since neither acted according to their own free will. Why should one be tried and not the other?We are at a crossroad. We either have to deny existence of the common conscience of all of the people of the world and consider the courts, punishment of those who disobey the law to be ridiculous and useless and even oppressive or deny the beliefs of the fatalists. Obviously the latter is preferable.
It is interesting to note that those who believe in the school of fatalism, and give reasons for their belief, when they are faced with a real life situation, they act according to free will! For instance, if a person aggresses against them, or annoys or bothers them, they take this person to court and do not rest at ease until that person is punished. Well, if it is really true that a person has no choice or free will, what are all of this commotion and court and trial about?
At any rate, this common conscience of the intelligent of the world is a living idea for the reality that human beings have accepted the existence of free will in the depths of their being and has always been loyal to that and cannot live without the belief for even one day and have the wheels of social and individual programs progress.
A great Iranian philosopher, Khawjeh Nair al-din Tusi, in discussing predestination and free will says in one short sentence in his book Kitab Tajrubah bih al-Aqa’id, “Our necessary understanding and conscience tells us that we are responsible for all of our deeds.”
Ref: Fifty Lessons of Principles of Belief for Youths; Ayt. Makarem Shirazi; Translated by: Bahador Shirazian; Published by: Ahlul Bayt World Assembly