The atheist neuroscientist Sam Harris claims that he agrees with Einstein, who did not believe in free will and connected scientific and moral truth. Fellow leftist-atheist-evolutionist Jerry Coyne agrees, and also denies free will, as he has in several recent posts.
To them, denying free will is essential to their materialist atheist humanist world view. They don't want to believe in good and evil, or supernatural purposes, or personal responsibility, or anything that might give religion meaning.
There are two main scientific arguments against free will. One is that materialism is necessarily deterministic, and the other is that certain brain functions give detectable clues a second in advance. Both of these arguments are entirely fallacious. Free will is a question for philosophy, not science.