Empirical Evidence

Essays, Stories, Adventures, Dreams
Chronicles of a Footloose Forester

By Dick Pellek


Empirical Evidence

In the sciences, the practitioners are always looking at circumstances with their own set of observational tools.  You might say that scientists go around with binoculars hanging from their necks because if and when they see something that attracts their attention, they are keen to get a closer look.  The Footloose Forester boldly professes that that is true, but he is not trying to be elitist by defining who or what a scientist is.  When anyone, regardless of their education or experience, employs the scientific method, they are playing the role of a scientist.  It is not about education, it is about the keenness of observation, the self-imposed discipline to test, to experiment, and to hypothesize about circumstances that present themselves.  After all, most of the worldly scientists from our distant past did not have high formal educations.  What distinguishes them in the pantheon of accomplished individuals were their accomplishments for which they are credited; and for which they amply demonstrated various aspects of the scientific method: observation, deliberation, supposition, testing, formulation of a hypothesis, testing of that hypothesis; and a public proclamation of their findings.  Newton’s proclaiming the theory of gravity in 1687 might not seem to have involved all aspects of the scientific method, but if you think about it, many aspects of the scientific method were there.

Sir Isaac Newton observed other repeatable phenomena but the theory of gravity and his laws of motion were contained in his first opus. When he supposed something knowable was at work, he deliberated and tested his theory until he was certain that it could be explained and he then successfully defended his ideas.  In 1687, Newton published Philosophae Naturalis Principia Mathematica, what is widely regarded to be one of the important books in the history of science. In it he describes universal gravitation and the three laws of motion, concepts that remained at the forefront of science for centuries after.

Unfortunately, not all aspects of the scientific method make use of hard evidence; not all aspects use all of the tools, all of the time.  Sometimes the observations are fleeting, sometimes the suppositions go unstated, sometimes the deliberations about a passing scene are delayed; and sometimes the testing and the construct of a hypothesis are not possible or even advisable.  Sometimes we must rely on indirect and out of reach empirical evidence to make a case.  Call it circumstantial evidence, the kind that is actually and statistically credited with more convictions in criminal law cases than the preferred physical evidence.

Empirical evidence is difficult to define adequately because parameters and boundaries are non-existent.   Empirical evidence, also known as sense experience, is a collective term for the knowledge or source of knowledge acquired by means of the senses, particularly by observation and experimentation. Before there were strict measurements supporting a body of evidence, there were mere observations and casual experiments that did not involve calculations and laboratory notebooks. Whereas any forthcoming or subsequent hard evidence should ideally be based on tangible and concrete entities that can be measured, weighed, or put through x-ray spectrometers and chemical analyses, empirical evidence is based on observations and presumed associations that link ideas together.  Raw explanations that depend on interpretation with or without the empirical evidence put the putative steps in the scientific method out of order, but they are so common that we forget that impromptu interpretations are also in the toolkit of scientists.

As more than a few TV comedians acknowledge, “I don’t have proof, but I know that it is true” is one way of saying that observed phenomena are powerful factors in consensus acceptance of some things for which there is no direct evidence.  Sometimes we have to begin with empirical evidence as a place to start.

The impetus for this chronicle is based on some empirical evidence witnessed by the Footloose Forester who noticed a strong correlation of seedling height growth as a function of distance to an irrigation water source.  There were many particulars that went into the scenario, thus it is necessary to explain the circumstances.  In a forestry tree seedling orchard in Cape Verde, lines of seedlings of various species were aligned in blocks in proximity to a single water spigot that was the sole source of irrigation water for the seedlings.  Each line had 10-12 seedlings of the same species and original outplanted size; but each line was progressively more distant from the spigot where buckets were filled for watering them. 


Flamengos forest tree nursery


Saplings develop from the seedling stage

The most common type of bucket used was a discarded cooking oil container that had a capacity of approximately 4 gallons.  Due to the weight of the water when the bucket was filled, the nursery employees started their periodic watering of the seedlings at the seedlings nearest to the spigot and continued doling out water down the line until the bucket was empty. The effects of the practice were visually dramatic; over time and during the course of in-nursery watering, the tree seedlings nearest to the spigot were always the tallest and the ones at the end of the line were always the shortest.  Why that was so required a bit of speculation and the empirical evidence at hand.  A full or nearly full bucket of water was most conveniently lightened by dispensing the water as soon as possible.  Although the instructions to the workers might have been to water every tree in the line and every line in the block of dissimilar seedlings, they always gave more water to the seedlings closest to the spigot. In addition to the empirical evidence that the tallest trees were located nearest to the spigot and that seedling height became regressively shorter down the line, the same pattern existed for other lines farther from the spigot.

What suppositions, speculations, experiments, and hypotheses might arise from the scenario in a forestry seedling nursery where there appeared to be differential height growth of individuals as a result of inadvertent but preferential nurturing methodology?  And what elements of the scientific method were summoned to propel the potentially important principles toward improvements in management beyond the simple observation based on empirical evidence? 

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