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Using Multidisciplinary Thinking to Approach Problems in a Complex World

Complex outcomes in human systems are a tough nut to crack when it comes to deciding what's really true. Any phenomena we might try to explain will have a host of competing theories, many of them seemingly plausible.

So how do we know what to go with?

One idea is to take a nod from the best. One of the most successful “explainers” of human behavior has been the cognitive psychologist Steven Pinker. His books have been massively influential, in part because they combine scientific rigor, explanatory power, and plainly excellent writing.

What's unique about Pinker is the range of sources he draws on. His book The Better Angels of Our Nature, a cogitation on the decline in relative violence in recent human history, draws on ideas from evolutionary psychology, forensic anthropology, statistics, social history, criminology, and a host of other fields. Pinker, like Vaclav Smil and Jared Diamond, is the opposite of the man with a hammer, ranging over much material to come to his conclusions.

In fact, when asked about the progress of social science as an explanatory arena over time, Pinker credited this cross-disciplinary focus:

Because of the unification with the sciences, there are more genuinely explanatory theories, and there’s a sense of progress, with more non-obvious things being discovered that have profound implications.

But, even better, Pinker gives out an outline for how a multidisciplinary thinker should approach problems in a complex world.


Here's the issue at stake: When we're viewing a complex phenomena—say, the decline in certain forms of violence in human history—it can be hard to come with up a rigorous explanation. We can't just set up repeated lab experiments and vary the conditions of human history to see what pops out, as with physics or chemistry.

So out of necessity, we must approach the problem in a different way.

In the above referenced interview, Pinker gives a wonderful example how to do it: Note how he carefully “cross-checks” from a variety of sources of data, developing a 3D view of the landscape he's trying to assess:

Pinker: Absolutely, I think most philosophers of science would say that all scientific generalizations are probabilistic rather than logically certain, more so for the social sciences because the systems you are studying are more complex than, say, molecules, and because there are fewer opportunities to intervene experimentally and to control every variable. But the exis­tence of the social sciences, including psychology, to the extent that they have discovered anything, shows that, despite the uncontrollability of human behavior, you can make some progress: you can do your best to control the nuisance variables that are not literally in your control; you can have analogues in a laboratory that simulate what you’re interested in and impose an experimental manipulation.

You can be clever about squeezing the last drop of causal information out of a correlational data set, and you can use converging evi­dence, the qualitative narratives of traditional history in combination with quantitative data sets and regression analyses that try to find patterns in them. But I also go to traditional historical narratives, partly as a sanity check. If you’re just manipulating numbers, you never know whether you’ve wan­dered into some preposterous conclusion by taking numbers too seriously that couldn’t possibly reflect reality. Also, it’s the narrative history that provides hypotheses that can then be tested. Very often a historian comes up with some plausible causal story, and that gives the social scientists something to do in squeezing a story out of the numbers.

Warburton: I wonder if you’ve got an example of just that, where you’ve combined the history and the social science?

Pinker: One example is the hypothesis that the Humanitarian Revolution during the Enlightenment, that is, the abolition of slavery, torture, cruel punishments, religious persecution, and so on, was a product of an expansion of empathy, which in turn was fueled by literacy and the consumption of novels and journalis­tic accounts. People read what life was like in other times and places, and then applied their sense of empathy more broadly, which gave them second thoughts about whether it’s a good idea to disembowel someone as a form of criminal punish­ment. So that’s a historical hypothesis. Lynn Hunt, a historian at the University of California–Berkeley, proposed it, and there are some psychological studies that show that, indeed, if people read a first-person account by someone unlike them, they will become more sympathetic to that individual, and also to the category of people that that individual represents.

So now we have a bit of experimental psychology supporting the historical qualita­tive narrative. And, in addition, one can go to economic histo­rians and see that, indeed, there was first a massive increase in the economic efficiency of manufacturing a book, then there was a massive increase in the number of books pub­lished, and finally there was a massive increase in the rate of literacy. So you’ve got a story that has at least three vertices: the historian’s hypothesis; the economic historians identifying exogenous variables that changed prior to the phenomenon we’re trying to explain, so the putative cause occurs before the putative effect; and then you have the experimental manipulation in a laboratory, showing that the intervening link is indeed plausible.

Pinker is saying, Look we can't just rely on “plausible narratives” generated by folks like the historians. There are too many possibilities that could be correct.

Nor can we rely purely on correlations (i.e., the rise in literacy statistically tracking the decline in violence) — they don't necessarily offer us a causative explanation. (Does the rise in literacy cause less violence, or is it vice versa? Or, does a third factor cause both?)

However, if we layer in some other known facts from areas we can experiment on — say, psychology or cognitive neuroscience — we can sometimes establish the causal link we need or, at worst, a better hypothesis of reality.

In this case, it would be the finding from psychology that certain forms of literacy do indeed increase empathy (for logical reasons).

Does this method give us absolute proof? No. However, it does allow us to propose and then test, re-test, alter, and strengthen or ultimately reject a hypothesis. (In other words, rigorous thinking.)

We can't stop here though. We have to take time to examine competing hypotheses — there may be a better fit. The interviewer continues on asking Pinker about this methodology:

Warburton: And so you conclude that the de-centering that occurs through novel-reading and first-person accounts probably did have a causal impact on the willingness of people to be violent to their peers?

Pinker: That’s right. And, of course, one has to rule out alternative hypotheses. One of them could be the growth of affluence: perhaps it’s simply a question of how pleasant your life is. If you live a longer and healthier and more enjoyable life, maybe you place a higher value on life in general, and, by extension, the lives of others. That would be an alternative hypothesis to the idea that there was an expansion of empathy fueled by greater literacy. But that can be ruled out by data from eco­nomic historians that show there was little increase in afflu­ence during the time of the Humanitarian Revolution. The increase in affluence really came later, in the 19th century, with the advent of the Industrial Revolution.


Let's review the process that Pinker has laid out, one that we might think about emulating as we examine the causes of complex phenomena in human systems:

  1. We observe an interesting phenomenon in need of explanation, one we feel capable of exploring.
  2. We propose and examine competing hypotheses that would explain the phenomena (set up in a falsifiable way, in harmony with the divide between science and pseudoscience laid out for us by the great Karl Popper).
  3. We examine a cross-section of: Empirical data relating to the phenomena; sensible qualitative inference (from multiple fields/disciplines, the more fundamental the better), and finally;  “Demonstrable” aspects of nature we are nearly certain about, arising from controlled experiment or other rigorous sources of knowledge ranging from engineering to biology to cognitive neuroscience.

What we end up with is not necessarily a bulletproof explanation, but probably the best we can do if we think carefully. A good cross-disciplinary examination with quantitative and qualitative sources coming into equal play, and a good dose of judgment, can be far more rigorous than the gut instinct or plausible nonsense type stories that many of us lazily spout.

A Word of Caution

Although Pinker's “multiple vertices” approach to problem solving in complex domains can be powerful, we always have to be on guard for phenomena that we simply cannot explain at our current level of competence: We must have a “too hard” pile when competing explanations come out “too close to call” or we otherwise feel we're outside of our circle of competence. Always tread carefully and be sure to follow Darwin's Golden Rule: Contrary facts are more important than confirming ones. Be ready to change your mind, like Darwin, when the facts don't go your way.


Still Interested? For some more Pinker goodness check out our prior posts on his work, or check out a few of his books like How the Mind Works or The Blank Slate: The Modern Denial of Human Nature.

The Map is Not the Territory