Pierre Duhem

Pierre Duhem (6 June 1861 – 14 September 1916). Pierre Duhem was a French born philosopher and physicists who worked in the field of thermodynamics and worked clear up the relationship between evidence and theory.

In his most notable work, The Aim and Structure of Physical Theory, he explained many of his theories on the topics of instrumentalism, how evidence does not certainly reject a theory (Duhem - Quine thesis) and the holistic view of science. He also opposed Newton's statement that gravity was deduced from phenomena and the entire structure of induction.

Historical Context

Pierre Duhem held conservative political and religious views while working the the late 19th century French society whose scientists were liberal and often very anti-religious.

His main works in science and the work he is best known for is the work he did on thermodynamics. His work spans from his failed dissertation in 1885 to 1911. He believed that generalized thermodynamics could provide the foundation of all physics and chemistry.

In philosophy of science, he worked on the theory surrounding the relationship between a theory and experiment. He rejected both Newton's theory and atomism accepting his own idea of thermodynamics. Although Duhem's rejection of atomism was a belief in instrumentalism, he did believe that there was an ultimate truth. Certain groups of physics such as thermodynamics was a way to reach it.

Major Contributions

1. Duhem on both the inductive method and hypothetico-deductive method

Duhem thesis: Experiments in physics are observations of phenomena with interpretations so physicists do not submit a single hypothesis but whole group of hypothesis. Therefore, experimental evidence cannot falsify isolated hypothesis.

The consequences of this thesis are far reaching. In fact, it calls into questions the method of science we use today. The hypothetico deductive method we use today starts by proposing a hypothesis and then deducing consequences. These consequences are then tested or observed. Continuous with the hypothetico deductive method is the notion of falsification. It allows for rejection of a hypothesis if the opposite of once of the consequences is observed. It is evidence against the hypothesis.

The Duhem thesis turns this falsification to something else. According to the Duhem thesis, when a predicted consequence is not observed, there is a falsity in the whole cloud of assumptions made in addition to the hypothesis. This means we do not know of any physical theory regardless of any evidence one provides in support or against the theory.

Duhem believed in the science of thermodynamics and saw it as a replacement for general sciences. He saw it as the foundation for all physics and chemistry.

Duhem criticized Newton’s methodology. In short, Newton uses Kepler’s 3 laws of planetary motion to derive his law of universal gravity. However, Duhem believes that the derivation is not possible since it contradicts Kepler’s law. He expressed the sentiment in the following: The principle of universal gravity, very far from being derivable by generalization and induction from the observational laws of Kepler, formally contradicts these laws. If Newton’s theory is correct, Kepler’s laws are necessarily false."

2. Duhem on Infallibilism Duhem believed science is perfect only when fully rid of empirical knowledge, when it is informative and when it is open to correctness. Despite this, he was an infallibilist who believed common sense to be infallible.

With that said however, he took the first step towards fallibilism. His belief that negative results tell us that there is a problem but does not tell us where the error is soon evolved. Quine had his nonuniqueness thesis, stating for every theory given evidence, there is at least one other theory that is also supported by the same evidence. Together they created the Duhem-Quine theorem: for any falsification, it is always possible to preserve a hypothesis by changing auxiliary hypothesis. Essentially given falsifiability, it is impossible to know if the theory was incorrect or any underlying assumption was incorrect.

Together they created the Duhem – Quine thesis which simply goes: Theories are tested in groups. If a theory with its assumptions logically predict an outcome and that outcome does not happen, we do not know whether the theory is at fault or the countless assumptions.

3. Duhem on Metaphysics Unlike his predecessor, Duhem believed metaphysics was a real form of knowledge, and in fact, surpasses physics in excellence in terms of providing understanding of things in a much deeper and intimate sense. Duhem believed that in order to understand the external world to the best of our abilities, two things needed to be done. 1. First is to study the world of phenomena and find the laws that govern them. 2. Scientists must induce from the phenomena, the properties of the substances that cause them. The second part is called metaphysics.

Duhem confronted criticism of metaphysics by redefining and clarifying some notions and terms, which he had.

In order for metaphysics to be knowledge, the logical priority is given to physics over metaphysics. This is because we cannot know any information or conduct any metaphysical investigation logically if we do not have an understanding of the physics driving the phenomena. While it is possible to deduce true physics from metaphysical ideas, it is incredibly difficult and dangerous in practice.

Another distinction is between truths of metaphysics and metaphysical systems. Metaphysical truths are from the result of physical observations of phenomena and given to the substances which cause them. They are often few and give negative information. Metaphysical systems on the other hand are usually positive judgements, most of the time hypothetical that tries to relate metaphysical truths in a logical order. Metaphysical systems are theoretically acceptable, if they do not contradict metaphysical truths, but have always been problematic. Metaphysical systems are often too general and have little determinate to be able to deduce physical laws. Lastly, a proposition derived from metaphysical systems are plagued with problematic characteristics that affect the metaphysical system itself and therefore, can only play an advisory role in what physics should examine. Physics alone must decide whether the proposition is correct or incorrect.

Lastly, metaphysical theories and physical theories are independent of each other. When making a theory, people use observations and then summarize their observations into laws. Theories classify experimental laws. When we have a set of experimental laws from experiments, we create theories. These theories are the same as the collection of laws. They do not convey more and try not to convey less information. When physical laws become theories, they are connected but the theory convey the same information as the separate laws. It is important to understand that while theories are easier, simpler, and perhaps more beautiful than the collection of laws they come from, they have the same foundation and do not change in character or content from the laws they were created from. They stay as physics and do not become metaphysics. In summary, a group of experimental laws teach us nothing about the foundation of the laws or the nature of phenomena they govern. Similarly, laws of physical theory add nothing to the content of the laws, only providing jumping points for metaphysical investigation. Physical theories do not exert influence on the progress of metaphysical research except for these points. In short, metaphysical and physical theories are independent.

Criticism

There were many criticism for the Duhem-Quine thesis and the Duhem thesis in general. Grünbaum believed there was no general argument to prove the existence of at least one other theory for any theory containing evidence.The main criticism was voiced by Larry Lauden in Demystifying Underdeterminism. The idea was also repeated in the identical rivals objection. The main argument is that in all the cases where there are seemingly endless theories that explain one theory and it's observations, (essentially in all instances of Quine's nonuniqueness thesis), the theories are actually the same but just formulated differently. John Norton summarized this by saying "“The very fact that observational equivalence can be demonstrated by arguments brief enough to be included in a journal article means that we cannot preclude the possibility that the theories are merely variant formulations of the same theory.”

Publications

Here are the works of Duhem included in the bibliographic records of this encyclopedia:

• Duhem (1996): Duhem, Pierre. (1996) Essays in the History and Philosophy of Science. Hackett Publishing Company.
• Duhem (1962): Duhem, Pierre. (1962) The Aim and Structure of Physical Theory. Atheneum.
• Duhem (1914): Duhem, Pierre. (1914) La théorie Physique: son Objet et sa Structure. M. Rivière.
• Duhem (1903): Duhem, Pierre. (1903) Analysis of Mach's The Science of Mechanics: A Critical and Historical Account of Its Development. In Duhem (1996), 72-112.
• Duhem (1893): Duhem, Pierre. (1893) Physics and Metaphysics. In Duhem (1996), 2-29.

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