More Hypothesis Templates

This post was edited by Phuoc Huynh on Dec, 2016
NOVA Geoblog has a nice discussion with illustration of how to help geology students think about two different ways that something can get to be spherical: an oolite gets round by accreting on all of its sides as it rolls around and experiences chemical precipitation, but a quartz sand grain gets round by being abraded on all of its sides as it rolls around and experiences physical weathering. The observable result (a spherical grain) is similar, but the processes is different.

Callan's well- stated and well-illustrated example with the oolites and the clastic grain could be the basis for a new "hypothesis template."

If you observe something spherical or near spherical, possible causal hypotheses are that:
* it got that way by building up in layers, building up evenly on all sides (e.g. hailstone, oolite.)
* it got that way by starting out irregular in shape and had its corners and protrusions abraded off (e.g. quartz sand grain.)
* it formed under conditions where the internal gravitational attraction of the body itself was more than the gravitational attraction of external objects (e.g. a planet, ball bearings made in the space shuttle www.enotes.com/how-products-encyclopedia/ball-bearing.)

In follow-up to my previous comment about a hypothesis template for spherical objects, the Sciences Times today has an article about spherical objects in nature and art: "The Circular Logic of the Universe," by Natalie Angier (http://www.nytimes.com/2009/12/08/science/08angier.html?_r=1&scp=1&sq...)

The New York Times has an intriguing article about the scientific controversy over the origin of the so-called "fairy circles" found in desert areas of Africa. These are circular areas that completely lack plants, surrounded by areas covered with grasses. Judging from the photos in the article, these things are about 20 feet in diameter, and there are hundreds or thousands of them. Hypotheses on the table include water competition, termites, and poison. The Nov 1, 2022 article reports on a new study that favors the water-competition hypothesis and weakens the termite hypothesis. In the context of "hypothesis templates," this controversy reaffirms that Earth and environmental scientists do spend considerable time, money, and ingenuity on trying to explain the causal mechanisms of distinctive geometrical and spatial features in nature.

"In hunt to solve 'fairy circle' mystery, one suspect is dismissed" by Rachel Nuwer
https://www.nytimes.com/2022/11/01/science/fairy-circles-cause-water-termites...

This post is now 14 years old, but I still find the idea of hypothesis templates useful as an entry point into thinking about what kind of causal mechanism could underlie a pattern observed in real world data. I would like to add one more hypothesis template to the "co-occurence in space of phenomenon A and B." Such a pattern of co-occurence could also be caused by a reinforcing feedback loop, in which an increase in A leads to an increase in B, and an increase in B also leads to an increase in A.

This line of thought was inspired by reading Ogorevc et al (2020) Social feedback loop in organic food purchase decision-making at: https://www.mdpi.com/2071-1050/12/10/4174 Those researchers applied a "spatial lag model" to a large international survey dataset and documented a pattern in which the more frequently the people "close" to an individual "make a special effort to buy fruit and vegetables grown without pesticides or chemicals" then the more frequently that individual will also make such a special effort. They interpreted this pattern as resulting from a reinforcing feedback loop working as follows: as the number of individuals doing behavior X increases, the social norm favoring doing X ramps up, and as the social norm ramps up, individuals will be incentivized to do X to fit in with the group, and the number of individuals doing X will also increase. The paper discusses implications for how to structure efforts to encourage purchase of organic food and other sustainability behaviors by leveraging such social feedback loops.

Interestingly, these researchers don't use the terms "close to" and "spatial" the way most geoscientists would, to refer to physical space. Instead, they define "neighbors" as individuals who reside in the same country, and have similar age, and years of schooling. They make a "dissimilarity matrix" based on gender, age, and years of school to quantify "distance." Then they quantify how much pro-organic-food social norm an individual would be exposed to by heavily weighting the survey answers of people "close to" that individual on this dimension of social distance.

In most data-based papers I have read about feedback loops, the researchers infer the possible existence of a reinforcing loop by looking for evidence of exponential growth or decay in behavior over time rather than by looking for co-occurence in "space." This is a different strategy for seeking answers to the eternal question of "what underlying mechanism could be causing this pattern that I am seeing in the world?"