As I understand it, most decisions are made in the sub-conscious part of the brain and are only passed into the conscious part of the brain later. the conscious part of the brain then has to explain why the decision was made. That's why some reasons for a decision sound really weak.
What we really have, if we care to admit it, is free will only to the extent that we see many, many choices we could make and then choose to think we made a free choice whilst it was rather the interactions in the sub-conscious brain that did the deciding. Thus we think we have free will and assume others act the same.