Contributions to a History of Experimental Controls

Arguably, controls are a key feature of scientific experimentation, yet, there are very few studies of concept of experimental control. Historical and philosophical analyses of control experiments have mostly concentrated on randomized controlled trials as “gold standard” for experiment-based inferences in medicine and specifically on the concept of randomization (e.g. Cartwright, Keating & Cambrosio). Apart from a paper by Edwin Boring on the nature and history of experimental controls, published in 1954, broader analyses do not exist. 

 

Boring interprets John Stuart Mill’s Method of Difference from System of Logic as the first philosophical conceptualization of controlled experiments. He also claims that the very term “control” appears in the scientific literature only in the late 19th century. In my paper, I turn the attention away from Mill to working scientists’ own conceptualizations of experimental practice. Examining the experimenters’ working philosophies reveals that there is a dramatic difference between the pragmatic concerns of the experimenters and the systematic concerns of philosophers. Focusing on accounts of experiments on plant growth and plant nutrition in the German lands, I show that around 1840, control experiments – Controleversuche – were common in agricultural field trials to investigate the influence of air, water, minerals and organic materials on plant growth. I trace this notion of control to two related contexts: late 18th-century technical-economic experimentation and methodological reflections on the analytic tools of organic chemistry around 1800. My analysis of these early instances of “control” suggests a distinction between two kinds of experimental controls that is not represented in Boring’s work but is well represented in 19th-century discussions of experimental methods in the life sciences.

 

This event is part of the Princeton University History of Science Colloquium.