Is truth unknowable?

One of my favorite movie scenes is in A Few Good Men. Tom Cruise is cross examining Jack Nicholson during a military court marshal about an incident that happened on the battle field.  We've probably all seen or at least heard someone say the famous line that Nicholson uses.  Here's the clip just because I love the imaginery of it.



I'll get back to the clip in a minute.  A few years back my brother was out hunting with his son.  They were looking for deer and my nephew spots some but my brother couldn't see them.  He immediately realized that he needed eyeglasses.  His vision had degraded over time like it does for most of us and it was so gradual he hadn't noticed it.  The fix was easy, he went to the eye Dr. and got glasses.  But it took my nephew, who had better eyesight, to point it out to him.  Imagine if he went to the eye Dr. and the Dr. told him he needed glasses to be able to see things and my brother replied "That's just your perception that my eyesight is bad.  How can you know that?  I can see all kinds of things so I don't accept your perception."   That's kind of absurd but people do that with the world around them all the time.

I first encountered this in college or at least it was the first time I paid attention to this kind of thinking.  I took a philosophy class and one of the philosophiers we studied was Immanual Kant.  In a nutshell Kant says we can't really know the world around us all we know is what we perceive.  In otherwords we "Kant" know the truth.  At the time I felt like this was a bunch of hooey because my own experience about the world told me otherwise but I didn't know how to refute it.  This kind of thinking and variations of it are rampant in our society but is it actually true?  Can we know truth or is truth unknowable?

Any statement that makes a claim about the world must hold valid against it's own claim.  If I say "Don't believe a word I say" that statement must apply to itself.  So in this example I'm asking you to "Believe me that you shouldn't believe a word I say".  Believe me but don't believe me.  That statement doesn't even stand up to it's own claim so therefore it's false.  This is a logical fallacy because it's self contradictory.

So when someone says "Truth isn't knowable"  Ask them "Is it true that truth isn't knowable?"  Or "How do you know that truth isn't knowable?"  This statement commits the self contradictory logic fallacy though and many times they miss the point completely.  They will likely give some long explanation about how they know that truth isn't knowable.  Sometimes they even think you're pulling some sort of slight of hand or tricking them but you're just applying their own statement to itself.  They are telling you that truth isn't knowable but then go on tell you something that they know about truth, that it's unknowable.  The statement can't stand up to it's own claim and therefore is false.  In otherwords their statement can't handle the truth!