First of all, I do not have much mathematical background and I have minimal category theory knowledge. I am just trying to understand one or two things about category theory because the concept sounds interesting. Please do not give answers like those in MacLane's book i.e answers for the working mathematician.
I understand that in Dual categories, all morphisms are essentially reversed.
For example having this Pullback in the category of sets, will reversing $p_1$ and $p_2$ leaving all the elements inside the set as they are and the functions represented by the morphisms $p_1$,$p_2$ also as is but just switching the domain and codomain make it a pushout?