Once upon a time (624 BC) Thales was born. Thus began philosophy.
Thales invented criticism. Instead of telling his followers what to believe, he made suggestions, and asked that they think for themselves and form their own ideas.
A little later, Xenophanes invented fallibility and the idea of seeking the truth to improve our knowledge without finding the final truth. He also identified and criticized parochialism.
In the tradition of Thales and Xenophanes came Socrates, the man who was wise for admitting his vast ignorance (among other things).
But only two generations after Socrates, philosophy was changed dramatically by Aristotle. Aristotle invented justificationism which has been the dominant school of philosophy since, and which opposes the critical, fallibilist philosophies which preceded him (and which were revived by Popper and Deutsch).
Aristotle's way of thinking had some major strands such as:
1) he wanted episteme -- objectively true knowledge.
2) he wanted to guarantee that he really had episteme -- he wanted justified, true knowledge. he rejected doxa (conjecture).
3) he thought he had episteme -- he was "the man who knows"
4) he thought he had justification
5) in relation to this, he invented induction as a method of justifying knowledge
Thus Aristotle rejected the fallibilist, uncertain ethos of striving to improve that preceded him, and replaced it with an authoritarian approach seeking guarantees and to establish existing knowledge against doubt.
Induction, as well as all other attempts, were unable to justify knowledge. Nothing can guarantee that some idea is episteme, so all attempts to do it failed.
Much later, Bacon attached induction to science and empiricism. And some people like Hume noticed it didn't work. But they didn't know what to do without it because they were still focussed on the same problem situation Aristotle had laid out: that we should justify our knowledge and find guarantees. So without induction they still had to figure out how to do that, and salvaging induction seemed easier than starting over. Hence the persistent interest in reviving induction.
What Popper did is go back to the old pre-Aristotle philosophical tradition which favors criticism and fallibilism, and which has no need for justification. Popper accepted that doxa (conjectures) have value, as Xenophanes had, and he explained how we can improve our knowledge without justification. He also refuted a bunch of justificationist ideas.
Then David Deutsch wrote "A Conversation About Justification" in _The Fabric of Reality_.
So how does that relate to free will? The basic argument against free will goes like this, "There is no way to justify free will, or guarantee it exists, therefore it's nonsense." The primary argument against free will is nothing but a demand for justification in the Aristotelian style.
As an example, one might say free will is nothing but a conjecture without an empirical evidence. To translate, that means free will is merely doxa, and hasn't got any empirical justification. This is essentially true, but not actually a problem.
Arguments against free will take many guises, but justificationist thinking is the basic theme giving them appeal.