‘So, a lot of us figure that our thoughts and actions are free. But, most of us also believe that every effect has a cause, and that everything that happens now, in the present, is the necessary result of events that occurred in the past. This view is known as hard determinism. And [many people would argue that both can be true]; that many of your actions are free, and that the world is governed by cause and effect.
But, it turns out, you can’t rationally hold both views. Because, traditionally, libertarians have defined free actions according to what’s known as the Principle of Alternate Possibilities. That might sound like the plot device for a sci-fi show, but this principle says that an action is free only if the agent – that is, the person doing the thing – could have done otherwise.
So, truly free actions require options. Determinism, by contrast, doesn’t allow options. It holds that every event is caused by a previous event. Which means that an agent can never have done anything other than what they did, and therefore, they are never free.’
– Green. H. (2016, August 15) Determinism vs Free Will: Crash Course Philosophy #24