How could we trust our consciousness ?!

[Angrboda]

This is similar to the question of how we can trust inductive reasoning. Logically, we can't. Take the black swan problem. For a long time, Europeans presumed that all swans were white because they had not encountered a black swan up until that point. Their sample of possible swans only included white ones. But that did not prevent the existence of black swans outside of the sample of swans they possessed. We may know the contents of the sample we are aware of, but that tells us nothing about the total size of the pool of possible instances that our inductive inference is about, so we have no basis for estimating that the next sample will be consistent with the characteristics of the current sample. Thus you cannot justify using inductive inference on purely logical or a priori grounds. Yet all the same it has been a useful tool because such inferences have proven to be generally reliable. As one philosopher put it, inductive inference cannot be justified, but it can be validated, through use and experience. Inductive inference will not reliably work in all possible worlds that we may find ourselves in, but in the actual worlds that we do find ourselves in, because of the general homogeneity of phenomenon, it proves itself to be a useful and reliable tool through its use and track record. I might point out that depending upon the reliability of inductive inference itself in this way leads to yet another inductive inference, namely that of whether inductive inference itself will continue to be reliable, but perhaps that may be justifiable upon a priori principles, whereas inductive inference in general cannot be (I have an idea or two based upon Ramsey theory, but it may not pan out; it may just be a paradox). In a similar way, perhaps the reliability of evolved brains cannot be justified based upon a priori reasoning, though I would follow Gae's suggestion and say that we mean something other than infallibility by "reliable" here, something which may be demonstrable. Even if not, even if we cannot justify the reliability of our brains and reasoning through a priori reasoning, a bit of a paradox itself, we can nonetheless validate that it has and likely will continue to be reliable based upon experience. If validation rather than justification is good enough, and if inductive inference on the whole can be put on a firm footing by the method outlined above, then we don't need logical justification for our belief at all. To use a time honored truism, "The proof is in the pudding."

This is one tack by which one can approach the question. I have another which I may explore, depending. Regardless, it seems something of a paradox to even ask the question, as in order to prove that reasoning is reliable, we have to first assume that our reasoning is reliable, or else we never get off the ground. This reminds me of an obsefvation I made recently that all systems of knowledge and belief start with assumptions and build from there. The reliability of reason is similar. We cannot justify our reliance upon reason, but no other system can justify its base assumptions either. So in that regard, it is no better and no worse than any contrary belief. And so it seems while our belief in the effectiveness of our reason cannot be justified any better than its contrary belief, its justification is certainly no worse than that of its contrary. We must just assume that our reason is reliable and work from there. There is no good alternative.