Tu Quoque

Have you wondered why common things tend to have uncommon names? Or get referred to by uncommon, rather hifalutin terms? Must be because telling it in an everyday manner makes it sound so...ordinary...that saying it does not get you those oh-what-a-genius looks. AND, of course, really being a genius is sort of beyond you.
Take this one for example. Sounds like a logical fallacy that only an expert would come across or understand, right. 'Tu Quoque'...roll it round your tongue. Feels important, does it not?
THEN, consider this...
"You better buckle down and study every day, sonny! Life is competitive and the earlier you learn that the better."
"But, Grandpa said you never opened a book through school except when forced to..."
There are times when you wonder why your parents never get off your case. Just as you thought that, at last, they had lost their hold on your life...
Now, if sonny thought that studying every day COULD help him in life but YOU were preaching what you yourself did not practice - somewhat like knowing that a controlled diet is important for good health even while laughing at the fact that the guy who was preaching it was known to have a meal every hour on the hour - well, if sonny thought THAT, then you do not get to roll that 'Tu Quoque' off your tongue. For there is no flaw in his logic in calling you a hypocrite...though, yes, you would get back with "Do as I say, do not do as I do".
The problem is when he decides that the advice is incorrect because YOU did not practice it. In other words, if the chap who is putting forth a point is hypocritical enough not to apply it in HIS life it does not necessarily invalidate the point. To consider that the hypocrisy of the one who proposes a course of action necessarily invalidates the correctness of that course of action is the 'Tu Quoque' fallacy.
Of course you could simply say, "Just because the preacher is a hypocrite, you cannot consider what he preaches to be wrong". But then, that's only common-sense. 'Tu Quoque' fallacy...now THAT is a mark of Wisdom!