It has been claimed many times in this thread that our ability to exert conscious control of our thoughts is logically impossible.
Yep.
Yet in order to get to this reasoned argument you need to consciously control and verify the validity of the thought processes involved.
Nope. Your brain decides that it's going to say that, and your conscious awareness of that decision happens afterwards, we've shown that experimentally.
How can you possibly claim validity to a conclusion which has emanated from material reactions beyond our conscious control?
Because an argument stands on its merits, not on its origin. It doesn't matter who offers the argument, or how they came by it, it matters whether the logic holds.
The fact that we can consciously formulate reasoned argument and consciously validate them is ample evidence that we comprise more than unavoidable material reactions.
No. The fact that you describe it as a 'fact' that we consciously formulate arguments is belied by the neuroscience that shows we don't consciously formulate arguments, we become aware of the logic we've used to formulate an argument after our brain has done the logic for us. Even if we were consciously formulating the argument, of course, that wouldn't demonstrate that we were something more than material reactions, but your argument was flawed before that.
It is more than a feeling - it is a demonstrable truth.
Then demonstrate it, but you just keep asserting it.
O.