tag:blogger.com,1999:blog-8498149069472762986.post5378384729472247801..comments2023-10-22T04:50:28.588-07:00Comments on Life's Private Book: More Trouble With KantDavid T.http://www.blogger.com/profile/14828502773466162990noreply@blogger.comBlogger1125tag:blogger.com,1999:blog-8498149069472762986.post-77430316178661695372015-06-09T20:51:58.112-07:002015-06-09T20:51:58.112-07:00Hey, I like your posts on Kant – but I would point...Hey, I like your posts on Kant – but I would point out that we actually could in principle validly argue from a premise that we know the nature of something to the conclusion that we don't know the nature of something – it's called a reductio ad absurdum. That is, if we can validly derive a conclusion –P from P, this proves –P, because it invalidates P: if P were true, then P would also not be true – but this is absurd, so P cannot be true. It's a reductio ad absurdum. So the reason P is not true is because the conclusion derived from it is in contradiction to the premise (P), and THIS invalidates the premise. You assume a premise (P) and derive from it a contradiction (P & –P), and so the premise is disproved.<br /><br />More formally laid out<br />(1) If P then –P<br />(2) Provisionally assume P.<br />(3) –P (from 1, 2)<br />(4) P & –P (from 2,3)<br />(5) ^^ because we derived an absurd conclusion from our provisional assumption (2), we reject that assumption, so –P.Calebhttps://www.blogger.com/profile/00089853548699033807noreply@blogger.com