Wednesday, April 29, 2015

How Arguments Work: The "Rich Households = Unaffordable Houses ?" Graph and the Problems of Correlation, Causation, Selective Scrutiny and the Enthymeme

By Steven S. Vrooman

People are making lots of arguments about this graph in the past few days:
http://www.theatlantic.com/business/archive/2014/10/why-are-liberal-cities-so-unaffordable/382045/
A friend on Facebook, who is a political independent but is to the right of me, shared this article from The National Review, which spins this data to add to the GOP talking points post-Baltimore. The idea is that liberalism fails at [insert list of everything here] and that's why there is so much poverty in cities like these, which usually have Democrats in the mayor's offices.

As my friend posted, "Read this and tell me there's not a correlation!" I've written before on this common fallacy, this assumption that correlation equals causation.

There are many examples of the problems of this kind of reasoning, including graphs like this one:
http://www.fastcodesign.com/3030529/infographic-of-the-day/hilarious-graphs-prove-that-correlation-isnt-causation
When I teach this in class, I will often use the Superbowl stock market predictor or The Redskins Rule for the Presidency to show that just because things happen together doesn't mean that it means anything.

What makes a cause and effect relationship is that there is a logical, not a spurious, connection between the two things. In the real world there are piles or causes and effects all interacting together, so it is unlikely that we can always disentangle these things anyway.

But that logical connection idea is tricky. Perelman argues that we adapt our arguments to the values of our particular audiences. Evans' notion of selective scrutiny, that we ignore given reasoning and simply add our own logic to get to a plausible conclusion seems increasingly true in the arguments on social media about Baltimore.

And since a chart like this simply provides two data lines on the same graphical space, we are asked to provide our own reasoning. This, in argument-speak, is called an enthymeme, an incomplete argument.

The original article from The Atlantic suggested all sorts of reasons for this correlation, including that cities run by Democrats tend to be in the north or on the coasts, where for reasons of geography you can't simply expand and take over new empty lands for new housing. See, we simply backfill the data with speculation that fits our existing ideological biases.

The National Review suggests that this must mean all liberal policies caused these problems: the argument slides down the greased rail of its own abstraction as the word liberal then is adapted to mean anything the critic wants it to mean, regardless of its connection to the original data.

But how do we know what happened first, the housing trouble or the Democrat leadership? The poverty or the liberal policies?

It would be tempting to think that if we just look that up, we would have the answer!

I tried my version of that. Here's what I said on Facebook about it:


Steve Vrooman But mass transit is a different kind of liberalism than the elements attacked by the people who have used versions of the article like you posted. There is slippage under the word "liberal" which ends up being : "Here's why all liberal policies cause all this poverty!" which is not justified by the analysis. 

Additionally, affordable housing is always a casualty of population density, which is only possible when there is enough economic opportunity to allow for that density. So it moves outside of town, in which case we need mass transit to get the low wage workers into town. Or we need to establish rent controls to cordon off sections of affordable housing. Neither of those are liberal policies, inherently. They sound liberal from the perspective of post-Goldwater conservatism, but they are attempts to solve the problem of housing affordability, which have nothing to do with the liberals in the mayors offices, using what we now call liberal political solutions. 

There is a correlation, but it is the opposite of what you are espousing here. A free(ish) housing an development market inevitably increases rents in high-density urban centers. City governments usually like this kind of development and provide tax breaks to encourage it. This is conservative social engineering. Gentrification displaces people. There is an eventual liberal backlash which now has limited means of solving what is always a market problem.

I guess we can blame clean air and environment restrictions, too. But people complained about liberals making laws against throwing raw human waste on the streets from second floor windows 200 years ago, so our definitions of acceptable environmental restrictions shifts. But these are very small things have have little to do with the vast weight of the problem.

I am suggesting that The National Review has the causal order wrong. But this is how we get sucked down into Internet-argument rabbit-holes:
http://imgs.xkcd.com/comics/duty_calls.png
I might even go out and do the research to prove that my account is correct (because, of course, I am just making assumptions that are consistent with my ideology, as Evans would predict).

But THAT WOULD MISS THE POINT! :)

I would now have two lines on a graph that I connect with my ideology. One happened before the other, but that fallacy, post hoc, ergo propter hoc, is just as wrong as cum hoc, ergo protper hoc. The time difference doesn't magically make my argument correct.

You might suggest that if I did reallllllly gooood research I could find the TRUTH! And I would have reasoning and evidence that would prove beyond a reas
http://www.blogcdn.com/www.politicsdaily.com/media/2009/01/thomas-2.jpg
See? No one is listening. 

The trick to making a "good" argument is not the same as getting someone to process that argument. I'm not saying to just go out and make things up and manipulate (that would be a false dilemma fallacy, btw). 

I kind of wrote a book with some chapters on how to approach that very tricky thing, so, you know, a blog post probably isn't quite enough space to fully answer that question. But, because you will ask, here's a bit of the approach: You've got to complete the argument! No more incomplete enthymemes. And you've got to focus on the warrant (I've explained that before), usually the logic and/or values that connect your evidence to your conclusion. 

The focus you want is designed entirely to not let your audience fall into Evans' selective scrutiny. Here's a quick example of that from The Zombie Guide to Public Speaking book:


https://www.nasa.gov/sites/default/files/s62-05616.jpg
I think of John F. Kennedy’s (1962) “We Choose to Go to the Moon” speech. Delivered at Rice University, this address helped turned America’s vision toward an eventual moon landing. The typical excerpt is a clear double hierarchy: “We choose to go to the moon. We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard . . .” Americans typically have a hierarchy of difficult things. He establishes many points on that hierarchy in his speech, with examples of explorers and their deeds in America’s past. We also have an assumed hierarchy that places easier to do things as more important or worth more focus than hard things. This is one of the traditional, pragmatic American loci. Kennedy asks us to flip that around. He does it in lots of ways. He connects that with hierarchies of what makes great nations great, of fears of a Soviet-weaponized orbit, etc. But right before that famous quote, he provides another hierarchy for his audience, one that usually is not included in the video clips shown in documentaries: “Why does Rice play Texas?” Ahhh. He tells us to think through a sports analogy, a football analogy, especially in Texas. To get his audience to flip their hierarchy of easy and hard things in terms of government programs, he asks us to think about it in football terms. Rice plays Texas because losing that game is more important than never playing it. Sometimes we need to do things that are hard. It is a test of character.

Real persuasion is possible, but we know it is rare. I mean, we did go to the moon. But how often, in your Facebook arguments, do you take other people there? You, like me, probably often forget these things in the heat of battles.

1 comment:

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