According to what life taught me, stupid is the person that thinks he knows everything -when in fact knows hardly anything
This is basically my uncle, he thinks he know everything, and his always arguing with me, is facts are based on magazine articles made by common ppl for common ppl, i already quitted arguing with him, he always thinks he know everything and that i am the one without knowledge on the subject... Most of the times when he starts arguing with me i just smile, nod, tell him he is wrong and start a conversation with someone else, there are ppl in this world that are full of themselves, and trying to teach them new things is impossible, like you said "You cannot learn an old dog new tricks"
Well there are even younger people in their 30's insisting about things, who live to argue. I cannot understand that in any way... I think you found your way with your uncle and in my opinion its the smartest way to deal with them ;)