




































AQUINO VOLUME 2 ISSUE 2 DECEMBER 2022 FOR PDF


Abstract

The Duhem-Quine thesis on crucial experiment in physics states that the scientist can 
never submit an isolated hypothesis to experimental test because our statements about the 
physical world are inseparable and interconnected. Using the method of critical 
expository analysis, paper examines the plausibility of this thesis in relation to adequate 
description of the nature of science and its historical development. In doing this, the 
paper argues that the thesis is veracious because it captures the true nature of scientific 
inquires, debunks the existence of crucial experiments in science, unveils the 
underdetermination of scientific theories, punctures the hegemonic claims of modern 
science and in so doing encourages the use of different scientific methodologies in the 
attempt to explore, grasp, explain and exploit physical reality for human well-being. 
Consequently, the paper concludes that the Duhem-Quine thesis tends towards the 
conceptualization of science as a value-laden and culture sensitive enterprise and, as a 
result, rightly suggests that the falsification, nay condemnation, of certain knowledge 
claims as illegitimate and unscientific, using the canons of modern science, is inadequate 
and misleading.

Keywords: Duhem-Quine thesis, Underdetermination, Duhem, Quine, hypothesis or 
proposition

Introduction
The first sentence in Aristotle's Metaphysics is that: “All men by nature desire to 

know” (1). The implication of this is that the human person is a knowledge seeking being. 
Human beings have an irresistible urge to explore, penetrate, grasps, understand and 
explain reality. As rational beings, they always strive to demystify the mysterious, 
predict, manipulate and exploit nature to advantage. It is this natural human desire to 
know that makes human beings develop and adopt different methods that they think can 
help them to understand, explain, manipulate and exploit their complex, nay mysterious 
world better for the common good of humanity.

However, the development and adoption of different of methods of exploring and 
explaining reality by different groups of people interested in different aspects of reality 
has led to the emergence of different disciplines that can be broadly classified into three 

An Appraisal of Duhem-Quine's thesis on Crucial Experiments 
in Physics: An Essay in Philosophy of Science

Victor C. Nweke
University of Koblez-Landau

&
Martin F. Asiegbu

University of Nigeria, Nsukka

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groups, namely; the humanities, the natural sciences and the social sciences. Among these 
groups, the natural sciences are of the opinion that the ideal method for understanding and 
explaining the physical world is universal, objective and ahistorical. This method is 
known as the scientific method. The scientific method is presented by the natural sciences 
as the only method that has the capacity to help man understand and transform nature 
presumably because of “its ability to epitomize reality in its pure form” (Asiegbu 2005, 
117). The implication of this is that anyone, who hopes to acquire “authentic” knowledge, 
which physical sciences offer, necessarily to follow this scientific method” (Agbo 2004, 
116). In otherwords, the scientific method is the “the very paradigm of institutionalized 
rationality” (Newton-Smith 1981, 1).

At this point, it is pertinent to note that the basic tenets of scientific method 
include empirical observation, the formulation of hypotheses, logico-mathematical 
explanation, prediction, experimentation and verification (Eboh, 94 – 95; Alozie 2003, 19 
– 20). This statement implies that scientific method claims that true knowledge proceeds 
from facts given by the observation of natural phenomena. These facts must be objective 
and interpersonal in the sense that they are accessible to and indubitable for all normally 
equipped human observers. In addition the facts must be susceptible to logico-
mathematical explanation and crucial experimentation.  The acceptance of any of these 
facts as knowledge depends on the result of a series of tests and experiment they undergo. 
Any of the facts whose result is negative is falsified and rejected as a candidate for 
scientific theory. What this comes to is that knowledge in science is acquired piecemeal 
through observation, theory formulation and experimentation. ”Therefore every new 
theory must be logically consistent with existing ones” (Alozie 2006, 214 – 15). 

Contrary to this position, the Duhem-Quine thesis posits that no one can subject a 
single hypothesis derived from a given fact to experimental test independent of other facts 
(hypotheses) because our propositions, facts, hypothesis about the physical world/natural 
phenomenon are necessarily interconnected and inseparable. 

In what serves as the outline, although still part of the introduction, the paper is 
divided into four sections. Section one is gives the general view of the thesis that prepares 
the audience for Section two. This section considers Duhem's formulation of the thesis 
himself. Quine's formulation of the thesis exposes the singularly unique contribution of 
Quine and how he imposed his signature on the thesis. The significance of the thesis and a 
critical evaluation of same, before the conclusion. 

Duhem-Quine Thesis on Crucial Experiment
The Duhem-Quine thesis on crucial experiment in physics refers to the position of 

two different erudite scholars – from different continents,   different disciplines and of 
different centuries – concerning the nature of crucial experiments in physics in particular 
and the natural sciences in general. These two renowned scholars are Pierre Maurice 
Marie Duhem and Willard Van Orman Quine. Pierre Duhem, as he is popularly known, 
was a French Physicist, historian of and philosopher of science. In spite of his relatively 
short life (1861-1916), his intellectual output was outstanding enough to immortalize his 
name in the annals of great theoretical physicists.

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Willard Von Orman Quine (1908-2000) is regarded as one of the most influential 
American philosophers of his time. Out of the ninety-eight years he spent on earth, sixty-
five were spent in the academic world of research, writing and teaching. This 
comparatively long career enabled him to contribute greatly to the development of 
different branches of philosophy notably in logic, epistemology, philosophy of language, 
philosophy of logic and philosophy of science. No wonder Ullian (2006, 270) argues that: 
“No one since Russell has contributed so much to both philosophy and logic as Quine. No 
major philosopher has given anything much to logic nor has any important figure in logic 
borne Quine's stature as a philosopher” (270). In a more elaborate manner, Gibson 
summarized the intellectual legacies of Quine's when he avers:

From the foregoing biographical sketch, one will understand that there is a big 
historical and theoretical gap between Duhem and Quine. Historically, Quine was only 
but eight years when Duhem died. Theoretically, Duhem was primarily a physicist while 
Quine was a philosopher. The point underscored here is that Quine neither met Duhem 
nor was he a student of Duhem. The only point of connection between Duhem and Quine, 
which can be deduced from our biographical sketch, is that they both had an interest in and 
contributed to the development of philosophy of science. 

In this connection, their major, rather unique contribution in philosophy of 
science is what is today known as Duhem – Quine thesis. The thesis was, though, first 
conceived and developed by Duhem, it became more pronounced and popular in 
contemporary times due to its appropriation, further development and reinvigoration by 
Quine. Let us take a look at the original thesis of Duhem about science, on the one hand 
and then proceed to present Quine's version of the thesis, on the other.
Duhem's Thesis

The prevailing view about scientific knowledge during the days of Duhem is that 
every proposition or hypothesis about the physical world can be confirmed or falsified 
through experiment. Thus, after observation, a scientist documents and uses empirical 
observations to form an hypothesis about the observed phenomenon. But the hypothesis 
becomes a scientific theory/law when it is confirmed by crucial experiments. It ceases to 
be a scientific theory/law the day it is falsified by any empirical experiment. The import of 
this statement is that scientific knowledge is essentially objective, value-neutral and 
cumulative; therefore scientists can always detect and falsify an erroneous hypothesis 
whenever there is a conflict between a scientific theory and the result of an experiment. 

Crucial experiment is the view that we can discover and falsify an erroneous 
hypothesis that is found to be in conflict with experience independent of other 
hypotheses, making up a given scientific theory. Contrary to this position, Duhem in his 
book, The Aim and Structure of Physical Theory stresses the holistic character of 
verification and falsification in physics and in the process debunks the existence of 
crucial experiment in physics. According to Duhem, “a single hypothesis cannot be tested 
in isolation, since other auxiliary hypotheses will always be needed to draw empirical 
consequences from. The Duhem thesis implies that refutation is a more complex matter 
than it might appear” (Blackburn, 110). 

The crux of Duhem's original thesis is that our propositions about the physical 
world are essentially interconnected and, as a result, cannot be falsified singly by 

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experiments. All that experiments tell us about a given scientific theory, which is in 
conflict with experience, is that something is wrong with the theory. Yet, it cannot help us 
to pin-point and falsified the specific proposition or hypothesis that is erroneous. The 
implication is that the Duhem thesis is originally concerned only with the non-
falsifiability of physical propositions or hypotheses through empirical observation and 
experimentation. In line with this view, Ariel (2003) calls the original position of Duhem 
“non-fasifiability thesis.” 

The point envisaged here is that Duhem debunks the claim that we can refute any 
given proposition about the physical world in an isolated manner whenever they conflict 
with experience. This is because our propositions about the physical world are necessarily 
interconnected and inseparable. Thus, the attempt to falsify any given physical 
proposition necessarily affects other propositions about the physical world. This view 
was appropriated, further developed, reinvigorated and popularized by Quine. The 
question now is how did Quine appropriate, further developed, reinvigorate and 
popularized the Duhem thesis?
Quine's Thesis

Although different scholars can develop similar theories independently, even 
without knowing that their contemporaries are doing something similar. However, this 
case is not applicable to the Duhem – Quine thesis. Quine's appropriation of Duhem's 
thesis of non-falsifibility of isolated propositions about the physical world was 
acknowledged by Quine himself. In his famous essay “Two Dogmas of Empiricism”, 
Quine uses the Duhem's thesis of non-falsifiability to buttress his rejection of 
reductionism as a mere dogma of empiricism that lacks empirical evidence. Hence, Quine 
writes,

The dogma of reductionism survives in the supposition that each 
statement, taken in isolation from its fellows, can admit of confirmation or 
infirmation at all. My counter suggestion, issuing essentially from 
Carnap's doctrine of the physical world in the Aufbau is that our statement 
about the external world face the tribunal of sense experience not 
individually but only as a corporate body (41).
Anyone, who grasps the Duhem thesis of non-falsifiability as espoused in the 

preceding paragraph, immediately realizes that this citation from Quine is more or less a 
paraphrased repetition of Duhem's position. Of course, when one further discovers that 
Quine super-imposed the above citation with a footnote where he acknowledged: “This 
doctrine was well argued by Duhem” (41), then, our claim of Quine's appropriation of 
Duhem's thesis of non-falsifiability becomes indisputable. The Duhem-Quine thesis is 
therefore primarily the claim that the confirmation or falsification of our propositions 
about the physical world is a holistic enterprise.

It particularly posits “the non-separability and the non-falsifiability of single 
theoretical hypothesis” because empirical predictions can only be deduced from clusters 
of interconnected hypotheses (Soberg 2002, 3). To this extent, one may think that Quine 
simply repeated the position of Duhem, but when we dig further, one definitely realizes 
the unique contribution of Quine. The first fundamental thing Quine did to the Duhem's 

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thesis is to extend its scope. This is evident in Quine's position that:

The totality of our so-called knowledge or beliefs, from the mist causal 
matters of geography and history to the profoundest laws of atomic 
physics or even pure mathematics and logic, is a man-made fabric which 
impinges on experience only along the edge or, to change the figure, total 
science is like a field of force whose boundary conditions are experience 
(42).
At this point, one can notice that while Duhem restricts the scope of his non-

falsifiability thesis to theoretical physics, Quine extends the thesis to the whole edifice of 
human knowledge including mathematics and logic. In this sense, Quine's non-
falsifiability thesis “respects no boundary” (Soberg 2002, 7). In addition to extending the 
scope of the non-falsifiability thesis, Quine also introduced the revisibility thesis thus, 

A conflict with experience at the periphery occasions readjustments in the 
interior of the field. Truth values have to be redistributed over some of our 
statements. A re-evaluation of some statements entails re-evaluation of 
others, because of their logical interconnections… But the total field is so 
underdetermined by its boundary conditions, experience, that there is 
much latitude of choice as to what statements to re-evaluate in the light of 
any single contrary experience. No particular experience is so linked with 
any particular statements in the interior of the field, except indirectly 
through considerations of equilibrium affecting the field as a whole…. 
Any statement can be held true come what may, if we make drastic enough 
adjustments elsewhere in the system… Conversely, by the same token, no 
statement is immune to revisions (42 – 3).

Quine makes the point that all knowledge is circumscribed by experience. Quine 
is of the opinion that if we wish to hold a particular proposition as true, come what may, 
we can always adjust other proposition. This position is uniquely Quinean. In this regard, 
Quine appropriates, further developed, reinvigorates and popularizes the Duhemian non-
separability (non-falsifiability) thesis in relation to theoretical physics by applying it to 
the entire edifice of human knowledge and by introducing the revisibility thesis. It is 
against this backdrop that some scholars such as Barbosa (2008, 55) argues, “There is no 
such thing as the Duhem-Quine thesis. As famous as this “thesis” may be, Pierre Duhem 
and W. V. O. Quine held different points of view concerning natural science and how its 
theories affects other branches knowledge.” The veracity of this claim lies in the fact that 
the position of Duhem and that of Quine are neither logically identical nor equivalent. 
For, although Quine's position necessarily incorporates Duhem's non-falsifiability thesis 
concerning crucial experiments in physics, Duhem's thesis does not necessarily entail 
Quines thesis concerning the non-falsifiability and revisibility of the totality of 
knowledge. Duhem did not claim that, when there is some conflict with experience, we 
can always make enough adjustment elsewhere in the theory. He simply claims that when 
there is some conflict with experience, what is disconfirmed is necessarily ambiguous 

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(Arielo, 2013).
Notwithstanding the above acknowledged differences, the Duhem-Quinean 

thesis on crucial experiment in physics (see Pierre Duhem's The Aim and Structure of 
Physical Theory) and W. V. O. Quine's “Two Dogmas of Empiricism” argues that “a 
single scientific hypothesis cannot be tested in isolation, since other, auxiliary hypotheses 
will always be needed to draw empirical consequences from it” (Blackburn, 111). The 
thesis in this sense implies that refutation is very complex in nature. What this comes to is 
that scientific theories are necessarily underdetermined and value-laden. The claim of 
modern science to value neutrality, objectivity and external validity is therefore suspect. 
A scientific hypothesis can only be validly refuted holistically using its background 
theoretical framework and not isolatedly, independently and singly. Accordingly, Soberg 
adequately captures the crux of the Duhem-Quine thesis in a succinct manner thus;

The Duhem-Quine thesis refers to the relationship between theory and 
evidence. In particular, the thesis posits the non-separability and non-
falsifiability of single theoretical hypotheses (…). Non-separability 
means that empirical predictions can only be deduced from clusters of 
interconnected hypotheses. Anomalous evidence consequently implies 
falsity somewhere inside a theoretical network. In such cases non-
falsifiability obtains because pure logic cannot pin-point the exact 
culprit(s) in a theoretical maze responsible for a false prediction. Thus, 
even if the evidence is indisputable, the thesis essentially questions 
whether any empirical assessment of theory can be conclusive (3).

Duhem-Quine thesis debunks the validity of crucial experiment in physics by 
insisting that scientific propositions about the physical world are necessarily 
interconnected, non-separable, and non-falsifiable. From this, we infer that all scientific 
hypothesis, or propositions about the physical world, are necessarily underdetermined by 
their theoretical background, and value-laden, and as such renders it impossible for pure 
logic to help us pin-point and falsify any recalcitrant proposition or hypothesis that 
conflicts with experience in isolation from its theoretical background. The question that is 
now left for us is the plausibility and significance of the Duhem-Quine thesis in relation to 
the nature and development of science.

Evaluation and Conclusion 
A critical look at the Duhem-Quine thesis, in relation to the historical evolution of 

modern science, shows that it is a valid and veracious thesis. The historical evolution of 
modern science shows that every scientific proposition is always a product of a given 
logically interconnected theoretical matrix. Hence any attempt to falsify any given 
scientific proposition or hypothesis necessarily affects, if not usurps, the entire 
background theoretical framework. Hence, if scientists have been using crucial 
experiment to falsify scientific hypothesis as they claim, science would have remained 
static, sterile and dogmatic. The growth of modern science is predicated on the fact that 
scientists do not strictly adhere to the dictates of their methodological rules in practice. 

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For as Kuhn (1970, 77) “No process yet discovered by the historical study of scientific 
development at all resembles the methodological stereotype of falsification by direct 
comparison with nature.” The off-shot of this is that the Duhem-Quine thesis captures the 
true nature of science.

Indeed, the emergence of Quantum theory in physics clearly substantiates the 
plausibility and veracity of the Duhem-Quine thesis. This is the case because Quantum 
theory led eminent modern scientist to the conclusion that scientific propositions are 
relative to the theoretical framework of the observer; hence, their acceptance of the non-
separability and non-falsifiability of scientific propositions and by extension the non-
existence of crucial experiments. The prevailing interpretation of quantum theory is 
known as the “Copenhagen interpretation”. It is called the “Copenhagen interpretation” 
because it was in Copenhagen, the capital of Denmark, that Nobel winning physicists 
namely, Werner Heisenberg, Niels Bohr, Wolfgana Pauli and a few other  eminent 
physicists met, deliberate and present what they consider to be a  suitable interpretation of 
Quantum theory. A succinct presentation of their view will help to make our position more 
vivid. Accordingly, Alozie did a nice job when he writes:

We can summarize the Copenhagen interpretation of Bohr and 
Heisenberg by saying that Quantum theory of relativity is statistical and 
oppose to determinism and objectivity, as we know it. Copenhagen 
interpretation makes the point that it is meaningless to talk about the 
physical properties of quantum entities without precisely specifying the 
experimental arrangement by which we intend to measure them. Quantum 
reality is in part an observer-created reality, and human intention 
influences the structures of the physical world (Physics, 113 – 4).

The point envisaged here is that the prevailing interpretation of Quantum theory 
shows that theoretical physics, the core of the natural sciences, is fundamentally 
probabilistic, indeterministic and subjective. And it is impossible to talk of crucial 
experiment in a place where there is neither objectivity nor determinism. The import of 
this is that scientific propositions and hypothesis are essentially non-separable, 
underdetermined, non-falsifiable and value-laden. Progress in science is therefore 
revolutionary did not evolutionary. “The normal scientific tradition that emerges from a 
scientific revolution (that is, after the conflict between theory and experience) is not only 
incompatible but actually incommensurable with that which has gone before” (Kuhn, 
102).

Consequently, the significance of the Duhem-Quine thesis is that it helps us to 
understand the true nature of scientific knowledge in contrast to the ideological  
propaganda of the scientific community dictated and peddled by Western powers (Alozie 
Critical Rationalism, 218 – 19, Kanu, 285). In this connection, the Duhem-Quine thesis 
saves us from the unnecessary attempt to falsify, negate, eliminate and discard important 
knowledge claims, beliefs and propositions simply on the ground of crucial experiment as 
dictated by the procedural rules of a particular Western oriented, nay empiricist inspired 
scientific method. The corollary of this is the decentralization and liberation of scientific 

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knowledge so that every human culture and society can seek, devise and use any method 
at their disposal to explore, penetrate, exploit and harness nature towards meeting their 
existential needs, transform their societies and ensure their well-being. Against this back 
drop, one can argue that the logical conclusion of the Duhem-Quine thesis is 
methodological anarchism in science as buttressed and authenticated in Paul Feyerabend 
monument of a book, Against Method: Outline of Anarchistic Theory of Knowledge. 

Our contention here is that Feyerabend's philosophy of science is in-line with the 
Duhem-Quine thesis and that their major significance is the liberation of knowledge from 
the devastative canons of scientific method in order to encourage the unlimited progress 
of human knowledge. Owing to this, we conclude that the Duhem-Quine thesis just like 
Feyerabend's philosophy of science entails that every proposition about the world is 
essentially interconnected with its theoretical background. Therefore it challenges and 
allows every culture including the African culture to justify its propositions nay 
hypothesis or knowledge claims about the world from its unique theoretical framework. 
And as Ojong rightly wrote: “the challenge to develop African science with an alternative 
methodological approach is not an impossible task” (221). This challenge is very valid 
albeit possible and indispensable for Africa's scientific renaissance and development 
because the theoretical framework of African science and that of modern science and 
fundamentally different. 

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