Hmmm. I was being a little tongue in cheek as I thought you were.

But taking it very seriously, here goes..

These are generally accepted definitions of "disagree"
    Have or express a different opinion.
    Disapprove of.

Obviously "having different opinion." opinion is not an issue.
It is the expression of such an opinion that is of interest. Or worse still, the expression of disapproval.

If someone expresses a different opinion from the first and no one answers, then again, it is of little interest, if the holder of the original opinion says thank you kindly for the feed back, or less likely, changes their own opinion to match the second, or less likely still talks back and forth with the second until they both come to understand the other and agree to disagree, then we have a discussion.

If one or both take offense and "defend" themselves aggressively we have an argument.

Taking the above definitions as a starting point, and looking at your list, I see some reasons why people would have a difference of opinion. I see reasons why people would express a difference of opinion and in the case of "lack of empathy" I see, perhaps a reason why someone express disapproval.

Obviously the reasons that two or more persons might have a genuine difference of opinion are myriad but I this it all boils down to three things.

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.

The reasons for a disagreement to turn into an argument are basically psychological. Some would say that it has to do with ego, but I think it is more complicated than that. Some of the reasons I would put forth.

Column B

The desire to communicate.
The desire to prosthelytize.
The desire to dominate
monkey reflex
mischief

I may have missed something, I am just now formulating this idea, but I doubt that you can find a disagreement which has been expressed, which I would call, for arguments sake, an argument, that cannot be fully accounted for by factors from column's A & B.