Free will
Free will is the notion that human beings are able to choose between different courses of action in any given circumstance, whereas its opposite, determinism, claims that all our mental states and actions are made necessary by preceding causes, and we are therefore not free at all, although we may have the illusion thereof.
All of us have subjectively experienced being torn between doing one thing or another –what we would like to do, what we think we should do, or what we think others would appreciate our doing, and so on. We also assume that the decision is up to us, that we are free to do one thing or another, and others heap blame or praise on us assuming the same thing. This is what is meant by free will –the belief that whatever we may have done in actual fact, could have been otherwise had we decided on another course of action, and that before the action itself we were free to choose between at least two alternatives.
At the same time, we realise that the world works in ways we can understand because there are law-like processes that we can decipher, and that allow us to explain what happens around us. The principle operating here is that events are caused, not random, a principle that is known as determinism.
If the world is deterministic, that is it responds to patterns of cause and effect, then human actions are either an exception to this rule, or our feeling that we are free to decide what we like is simply an illusion.
We have trouble believing all our actions are determined, and that our sense of freedom is totally illusory, but we also have problems thinking that our actions are totally outside the realm of causality. The latter position would make our actions random, and this is not a palatable idea for most of us...
This is what in philosophy is known as the problem of free will, and it is a problem because whichever road we choose to go down seems to lead us to conclusions that we would have trouble accepting.