Pierre Duhem and the Role of Theory in Science

Pierre Duhem (1861-1916)

Pierre Maurice Marie Duhem (1861-1916)

On June 10, 1861, French physicist, mathematician, historian and philosopher of science Pierre Duhem was born. He is best known for his work on chemical thermodynamics, for his philosophical writings on the indeterminacy of experimental criteria, and for his historical research into the science of the European Middle Ages. As a scientist, Duhem also contributed to hydrodynamics and to the theory of elasticity.

“A physical theory … is a system of mathematical propositions, deduced from a small number of principles, which has the object of representing a set of experimental laws as simply, as completely, and as exactly as possible.” – Pierre Duhem, La théorie physique, son objet et sa structure, (1906)

Pierre Duhem – Early Years

Pierre Duhem was born in Paris, France, into a Flemish family as the eldest of four children to his father Pierre-Joseph Duhem, a commercial traveller, and Alexandrine Fabre. At age eleven he entered the Collège Stanislas where he graduated with outstanding achievements in Latin, Greek, science, and mathematics. Duhem’s father wanted him to study science at the École Polytechnique since he wanted his son to follow a technical career. Duhem’s mother, on the other hand, wanted him to study Latin and Greek at the École Normale. Being ranked first in the entrance examinations of both institutions Duhem chose to please neither of his parents by studying pure scientific at the École Normale in 1882.

A Rejected Thesis

In 1884, while still at the École Normale, Duhem published his first paper which was on electrochemical cells. Even before receiving his licence in mathematics, Duhem submitted his doctoral thesis in 1884. Suddenly his brilliant career shuddered to a halt. The thesis was on thermodynamic potential in physics and chemistry and in it he defined the criterion for chemical reactions in terms of free energy. In this he was replacing the incorrect criterion which Marcellin Berthelot had put forward twenty years earlier. Quite correctly Duhem criticised Berthelot’s theory putting forward a correct alternative. Sadly being right is not always good enough and a scientist as influential as Berthelot was able to arrange for Duhem’s thesis to be rejected.[1]

The second Thesis finally Accepted

Duhem knew he was right and boldly published the rejected thesis in 1886, when Berthelot became French Minister of Education. Unfortunately the hostility between Berthelot and Duhem was not dissipated until after 1900. Moreover, Duhem blamed Berthelot together with the circle of liberal and free-thinking scientists who advised successive ministers, for preventing him from ever receiving the expected call to a professorship in Paris.[2] Meanwhile, Duhem worked on a second thesis, this time wisely choosing a mathematical work on magnetism, which was finally accepted in 1888, while he was already teaching at Lille on hydrodynamics, elasticity, and accoustics, publishing these lectures in 1891.

Academic Career

Duhem taught at Lille (1887–1893), Rennes (1893–1894), and Bordeaux (1894–1916). He spurned an offer of a professorship in the history of science at the Collège de France shortly before his death, on the grounds that he was a physicist and would not enter Paris by the back door of history. In 1900 he was elected to corresponding membership in the Academy of Sciences, in 1913 he was elected one of the first six nonresident members of the Academy. Duhem died in September 1916 at fifty-five of a heart attack brought on by a walking expedition during vacation days at Cabrespine.

The Structure of Physical Theory

Duhem‘s views on the philosophy of science are explicated in his 1906 work The Aim and Structure of Physical Theory, where he opposed Newton‘s statement that the Principia‘s law of universal mutual gravitation was deduced from ‘phenomena‘, including Kepler‘s second and third laws. Newton‘s claims in this regard had already been attacked by critical proof-analyses of the German logician Leibniz and then most famously by Immanuel Kant, following Hume‘s logical critique of induction. But the novelty of Duhem‘s work was his proposal that Newton‘s theory of universal mutual gravity flatly contradicted Kepler‘s Laws of planetary motion because the interplanetary mutual gravitational perturbations caused deviations from Keplerian orbits. Since no proposition can be validly logically deduced from any it contradicts, according to Duhem, Newton must not have logically deduced his law of gravitation directly from Kepler‘s Laws.

A Devastating Critique of Baconian Experiments

Duhem’s name is given to the under-determination or Duhem–Quine thesis, which holds that for any given set of observations there is an innumerably large number of explanations. It is, in essence, the same as Hume’s critique of induction: all three variants point at the fact that empirical evidence cannot force the choice of a theory or its revision. Duhem argues that physics is subject to certain methodological limitations that do not affect other sciences. In his The Aim and Structure of Physical Theory (1914), Duhem provided a devastating critique of Baconian crucial experiments.[7] According to this critique, an experiment in physics is not simply an observation, but rather an interpretation of observations by means of a theoretical framework. Furthermore, no matter how well one constructs one’s experiment, it is impossible to subject an isolated single hypothesis to an experimental test.

The System of the World

Duhem is well known for his work on the history of science, which resulted in the ten volume Le système du monde: histoire des doctrines cosmologiques de Platon à Copernic (The System of the World: A History of Cosmological Doctrines from Plato to Copernicus, 1914). Unlike many former historians (e.g. Voltaire and Condorcet), who denigrated the Middle Ages, he endeavored to show that the Roman Catholic Church had helped foster Western science in one of its most fruitful periods. His work in this field was originally prompted by his research into the origins of statics, where he encountered the works of medieval mathematicians and philosophers such as John Buridan, Nicole Oresme and Roger Bacon, whose sophistication surprised him. He consequently came to regard them as the founders of modern science, having in his view anticipated many of the discoveries of Galileo Galilei and later thinkers.

Further Achievements

Duhem made a number of enduring contributions to thermodynamics and physical chemistry. Among these were the Duhem–Margules and Gibbs–Duhem equations, which deal with reversible processes in thermodynamics as quasi-static limiting processes and give a general proof of the Gibbs phase rule. These results were obtained in the context of a program of generalized thermodynamics called “energetics.”[3] Overall, Duhem published twenty-two books in forty-five volumes, as well as nearly 400 articles and book reviews in scientific and philosophical journals.

Michaela Massini, What Is Science? Pierre Duhem & Thomas Kuhn, [9]

References and Further Reading:

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