But, I'm having a problem with line 8: Dr Jason Campbell uses material implication on line 7 of the second column - the problem I have with this is that the rules of inference says:
From what I'm seeing in the above rule there is no formula which has a direct correspondence to the formula on line 7 i.e. a negation on each side of the variable (I think that's what it's called). There is a negation only on the left variable of the rule, but not on the right. So, how did he still use the rule?
This post has been edited by TechSyndrome: 14 July 2012 - 03:07 PM