Say that you believe X and I believe Y. If I present an argument for Y that amounts to presenting evidence for your consideration that Y is true and X is false. The implicit assumption behind arguing with anyone (even your self!) is that your mind is free to choose to believe X or Y, THAT is freewill.
If freewill is an "illusion" then "argument" is a hollow concept as well. If we don't have a choice in what to believe then what is the point of arguing?
I think argument still has a place in a world where freewill is illusory. Surely, one's opinions can change when presented with new evidence, regardless of whether that change originated from a free agent's conscious choice or a more deterministic background process of which one's consciousness is only partially aware. Furthermore, that change in opinion can have a meaningful effect either positively or negatively for both the conscious entity and the world at large.
Again, for the benefit of those who want to understand, you are smuggling in freewill via the concept "argument". You have no right to use that concept given your denial of freewill and it doesn't matter how many exceptions, qualifications or obfuscations you put on the concept "freewill", it is either a real capacity of our minds or it is not.
The essence of your position is that you are trying to convince me to change my mind and agree with you that I do not have the capacity to change my mind. It is a self-contradiction, as all forms of determinism are, and if you were consistent with your belief you wouldn't be arguing at all, yet here you are. I think (beyond a certain point) denying freewill is an inherently dishonest position but unfortunately you have plenty of company.
If you believe the sky to be green, someone may walk you outside and you will see the sky is blue. You do not choose at that moment to change your belief. You do not change your mind, your mind changes. There is no free will necessary here because updating your belief in response to evidence is not a conscious choice.
(Just explaining, personally I consider the question of free will to be a non-question.)
You are making assumptions. I never claimed I don't think freewill exists. Also, why would the absence of freewill prevent your mind from being changed based on the evidence another presents to you?
I would contend the opposite: all forms of indeterminism are self contradictory. Where does your free will come from? Either a choice is predetermined or it's truly random. What else could it be?
Indeed, the concept of free will is simply illogical and inconsistent. There is no space for it in even conscious experience if one is just honest about it. Sam has made that point quite clearly and Daniel Dennet's way out (a bit of randomness) seems weak to me.
If freewill is an "illusion" then "argument" is a hollow concept as well. If we don't have a choice in what to believe then what is the point of arguing?