(December 30, 2015 at 8:12 am)robvalue Wrote: It seems to me nothing could possibly ever rule out solipsism.You may be thinking of a weak form of “brain-in-a-vat / evilly deceptive demon” Cartesian solipsism as opposed to strong metaphysical solipsism. Nevertheless most people believe solipsism impossible to dismiss on rational grounds.
In Cartesian solipsism, there is at least a presumption that some kind of nomena lies behind phenomenal experience. In a Matrix or among zombies the personal existent still has a relationship with something outside themselves. It does not rule out the possibility of attaining knowledge either by “taking the red pill” or rational reflection.
Not so with strong solipsism in which all existence gets stacked on top of a single first-person observer. The claim of strong solipsism is this: that of which the first-person observer has knowledge is limited solely to that of which it is aware of in the exact moment during which it is aware. IF someone takes the stance that reality is intelligible AND the first-person observer is capable of knowledge THEN solipsism is self-refuting.* If even a single thing is independently true about reality then solipsism is mistaken.
There is at least one such property of reality that must be true independent of any observer. The first of which is the Principle of Non-Contradiction or PNC. If the PNC is true it must be universally and objectively true. If the PNC was subjective then the first-person observer would be able to contemplate its opposite: that something both exists and does not exist at the same time and in all ways. Anyone can see that this cannot be done. It doesn’t make any sense to say that solipsism is rational and at the same time say that the PNC is a subjective truth that depends on a mind’s contemplation of it. Something apart from the first-person observer constrains that which it is possible for the observer to concieve.
*The two qualifiers I mentioned (world intelligibility and capacity for knowledge) are important because absurdism always remains as an alternative existential stance.
