One of the earliest controlled trials may be a diet test in Daniel
In the first chapter of the Book of Daniel, Daniel and his companions ask for ten days on vegetables and water while other young men eat from the king's table, and the steward judges by the results. Some historians of science call it a rudimentary experimental design, though not everyone agrees it deserves that label.
An experiment manipulates one factor to see what follows, revealing cause and effect through a repeatable procedure. Controls hold other variables steady, and confounding factors, anything that could muddy interpretation, are removed by careful design or by randomly assigning subjects. Many philosophers of science argue an experiment can never prove a hypothesis, only support it; a clear counterexample can refute a theory, though defenders can always patch it with ad hoc changes at the cost of simplicity.
Practice differs by field. Physicists and engineers repeat identical procedures hoping for identical results and seldom randomise. Medicine and much social science follow the clinical trial model, randomly assigning people to treatment or control and focusing on the average difference between groups, with separate studies later combined in meta-analyses. Agricultural researchers randomise plots to compare fertilisers, while experimental economists often test theories of behaviour without random assignment.
Historians David Lindberg and James VanderKam both point to the Daniel episode as resembling empirical testing. A far more methodical approach appears in the optics research of Ibn al-Haytham, who built on Ptolemy's problems and urged scholars to treat every text they read as an enemy to be attacked from all sides, while suspecting their own prejudices too. Centuries later Francis Bacon, who lived from 1561 to 1626, mocked those who decide an answer first and then drag experience along like a captive, and laid out an ordered method of hypothesis, experiment and axiom.
The method bore fruit. Galileo timed falling bodies precisely; Antoine Lavoisier used experiments on combustion to establish conservation of mass; Louis Pasteur overturned spontaneous generation and helped found germ theory. In the early 20th century statisticians including Ronald Fisher, Jerzy Neyman and Gertrude Cox transformed how experiments are designed and analysed. Experiments also matter in classrooms, where hands-on work can raise test scores and deepen students' engagement over time.
Source: Experiment
