"Column A
"1. Differences in data; People have access to different information.
"2. Differences in filters; People filter information through different paradigms for example religion, education, prejudice.
"3. Differences in processing; Depending on age, damage and other factors not all human brains process the same way. Differences in empathy can be included here."

That an interesting and neat summary of reasons for disagreement.

Of the recent post with a.,b. and.c., it is

"a. A discussion in which disagreement is expressed; a debate."

that especially interests me, of which the above is neat.