In the study into free will, I've heard many people use the word "illusion" to describe free will. I think their reasoning is that since all matter behaves according to the rules of physics, people don't really have a choice in their action, and therefore the free will is just a feeling, an illusion or a mirage.
This line of thought is bewildering to me, given our knowledge of physics, and how we gradually learned that concepts that were once thought objective are actually subjective. For example, according to the special theory of relativity, two observers might disagree about the order of two events: For the first observer, event A happened before event B, while for the second observer, B happened before A. None of the two observers are suffering illusions. None of them are more correct than the other. They are both correct from their own point of view.
This is isn't easily grasped the first time you hear it, but it's been an undisputed fact for the last 100 years.
If we can accept that different observers might have such different perspectives, without using the term illusion, why is there a need to say that free will is an illusion? Can't we just say it's a different perspective, same as we do for physics?