The point is, nobody is saying the debt did not increase under Mulroney, of course it did, for the most part caused by interest on the debt. I am sure most of you understand the concept of compound interest, especially TORO, but when you continue to pay interest on interest and the principal, you get massive increases in the amount owing. Look at a mortgage, and figure out where you would be if you did not make any payments at all on the debt for, oh say, 9 years (84 - 93). For another example, RRSP's are built for compound interest, that is why they increase so fast.
Mulroney had balanced program spending, but I guess technically you could say he ran a deficit because he did not pay any interest payments on the debt. However, as has been pointed out here on many occasions, by those that were there, the appetite for interest payments was nil, and would have put many people out of work had they done this. I think, if I also recall correctly, the World Bank got involved in Canada's finances at some point in time, but just exactly when I do not remember.
Say all you want, but when a party runs a country for 29 of 38 years, most of the problems by default were caused by that party.