Demonology & Data Reduction

Imagine that your job is to describe all the ways things go wrong with the human psyche. And that you’re alive during the 16th century, or even the 11th. You have to describe how people are dangerous to themselves and others for the good of a society that is wracked by injury, disease, and rampant structural unfairness. Your system must be comprehensive, easy to understand and remember, and effective despite the fact that you have essentially no experimental data, very little in the way of diagnostic survey work, and basically you’re running off of shaky collective memory and folklore that is, itself, frequently destroyed or distorted by large scale civil trauma.

There is a system of mental disorder and civil unrest in the world, you have a minimal amount of information about it, and your goal is to represent it in a way that is useful to an ignorant populace.

Welcome to the world of demonology, and Data Reduction 101.


The Lanterne of Light is a 15th Century text that establishes, for the first time, the systematic hierarchy of Christian demons organised by sin. It existed as part of a social movement to interpret the Bible into the language of the uneducated (i.e., English), and has been so effective that to this day most of the secular west understand Lucifer as emblematic of Pride. By telling stories about the fall from heaven through this lens we have gained a surprisingly sophisticated view on how an emotional state functions and how it can destroy a life. Almost every westerner knows that there are seven deadly sins in total, even if they don’t comprehend that the movie “Seven” is essentially an interpretation of this anonymously sourced, early 1400s, English Lollard tract. What the Lanterne does is to systematise social threat, and to then represent that system in a way that is so compelling, it remains remembered while 2010 was it’s 600th anniversary.

This is, at its core, the exact same process that drives modern psychology. An understanding of the need and mechanism behind the Lanterne directly helps us to understand modern statistical practice. The only thing that has changed is a matter of degree: The amount and reliability of data available, the minimal level of complexity which retains utility, and the size of the community which can utilise the output. The Diagnostic and Statistical Manual of Mental Disorders (DSM), now in its fifth edition, is THE main tool for the categorisation of psychiatry. And it is, essentially, the Lanterne of Light (1410), Binsfield’s (1589), Michaelis’ (1613), and Barrett’s (1801) classifications of demons, and “Hierarchical Cluster Analysis: Comparison of Three Linkage Measures and Application to Psychological Data” (2015). These texts are all illustrative of the problems that plague (the demon “Merihem”) data reduction, and can be utilised to illustrate the misconceptions (“Pythius”) and temptations (“Mammon”) of trying to describe complex systems in simple terms:

  • Systematic scope (where does the body end? Pestilence and the hereditary condition)
  • Data resolution, sampling error and measurement bias (what is left unseen)
  • Reliance on surface condition (active psychosis and possession)
  • Validity and mutability of categories (seven sins, three lies)
  • An assumption of normality (psychological utility vs. anomaly)
  • Under-dispersion, overrepresentation, and other distributional limitations (how wide is hell? How dull are its legions?)
  • Interstitial domain and interpolation (everywhere there are faces, pareidolia)
  • Data reduction for communication (lies, damned lies, and statistics)
  • Cultural bias (the redefinition of gender and sexuality)
  • Motive (witch hunts of the 15th and 19th centuries)

Statistics, particularly when deployed systematically, are often misunderstood, but the manner in which they both succeed and fail are easily described in a huge number of contexts. Demonology is just one of the most fun.

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