Why do we disagree?

This question matters.  It determines the scope of debate and helps us understand differing viewpoints.  It is also answered with confusion or misinformation with hilarious frequency.  I'll touch on how to think about these disagreements and briefly highlight some examples of confusion in the tax and voter ID debates.  Anyway, why do we disagree?

In politics, it seems to come down to a few things:

1. Differing, empirically testable, ideas about the world (facts)
2. Differing, empirically testable, ideas about how the world works (models)
3. Differing ideas about the proper values and goals of society 
4. Differing ideas about the proper powers of government

or, if you like:

1. What is the world like?
2. What can we do about it?
3. What should we do about it?
4. How shouldn't we do it?

None of that is terribly controversial, but I think that people often confuse the origins of their disagreement.  

I often, for instance, hear conservatives saying that the government shouldn't raise taxes on the rich, but depending on who you talk to, the answer to why varies a lot.  For some it is "because they are job creators", but for others it is "because it isn't fair".  These world views have the same conclusion, but different implications.  We can, to some extent, test the proposition that raising taxes will mean less job creation.  If a person genuinely believes this to be the primary reason not to raise taxes on the rich, then empirical arguments are the most appropriate forum of discussion.  For the "it isn't fair" person, the proper arguments are philosophical--diminishing marginal utility, &c.  Of course, people often convolve many different types of reasons, or simply hold positions as an aspect of group identity, but the basic point still stands.

Now, I don't think it is impossible to convince people to change their positions in 3 & 4 type disagreements, but it's substantially harder.  It is, however, possible to give people better access to facts, and in many cases that changes the nature of the discussion for the better.

Presenting evidence of the extremely low incidence of voter ID fraud, for instance, seems to have shifted the debate from "we need to curb rampant voter ID fraud" to "it is right and proper for voters to show ID in order to vote".  In other words, the debate has shifted from an empirical one to an ideological one.  From my perspective, that is good, because ideological questions are the only valid questions to ask voters in my idealized constitutional anarchy model of government.   Voters are, in fact, quite bad at discerning which facts and models best reflect the real world.  But, they are excellent at determining what they think are good goals to focus on as a society, and what they think are categorically unacceptable ways of achieving those goals.

I'll have more on practical applications of this idea, and ways in which it might help move the debate forward in a later post.