Understanding Quine’s Naturalism Philosophy Via Epistemological Holism

The goal of this paper is to better understand Quine’s philosophy of science by explicating his naturalism and interaction with other academics. By tackling the indispensability argument from multiple angles, I build off Penelope Maddy’s theory about epistemological holism and speculate how a Quinean might react to such claims. First, I will introduce ontological naturalism and how Quine gathered sympathizers that would eventually stray for greener pastures. Using Quine’s naturalism as a foundation, I explore the Quine-Putnam Indispensability Argument (QPA) and how the conclusions question both the philosophy of science and philosophy of mathematics. 


The belief system called Naturalism, developed in the early 19th century as a literary and philosophical trend that analyzed how we look at the world. Opposing supernatural belief altogether, naturalism supposes that only scientific inquiry can tell us anything truthful about the world. Naturalists are highly critical of what to include in their ontology, concluding that spatiotemporal entities are their physical entities rather than a metaphysical representation of themselves. Those who have naturalistic tendencies believe that only natural forces govern the world and worldly bodies, and that truth can only be discovered through nature.

All breeds of naturalists agree that science is the only reliable way to answer questions regarding the nature of our reality. On top of that, they agree that we ought to accept any and all entities that our best scientific theories prove with reasonable empirical testing.

Quine’s Naturalism

Willard Van Orman Quine gives his take on naturalism:

“ [...] naturalism: abandonment of the goal of a first philosophy. It sees natural science as an inquiry into reality, fallible and corrigible but not answerable to any supra-scientific tribunal, and not in need of any justification beyond observation and the hypothetico-deductive method ... The naturalistic philosopher begins his reasoning within the inherited world theory as a going concern. He tentatively believes all of it, but believes also that some unidentified portions are wrong. He tries to improve, clarify, and understand the system from within. He is the busy sailor adrift on Neurath's boat.” 

It is worth noting here that Quine’s naturalism diverges from generic naturalism is a number of key ways that I will discuss in later sections. For the purpose of this work, I think it necessary to explicate my own constructed view of Quine’s naturalistic flavor.

With his paper Epistemology Naturalized, Quine jump started the naturalistic epistemology movement by highlighting the difficulties implicit within the relationship between epistemology and the empirical sciences. He further makes the claim that epistemology can be conceived of as a branch of cognitive psychology. Quine’s claims regarding the natural sciences and epistemology are built primarily from two propositions. The first proposition relies on epistemological holism and the second describes the role of epistemology with regard to understanding what, if any, explanatory power we have about empirical testing and the resulting theories produced by scientists.

A key contention point between Quine and Carnap lie within the second proposition regarding the role of epistemology. Quine believes that there are two paths that allow us to examine scientific theories and their evidence (epistemology). He says that one way to do this explanatory work would be to attempt a “logical reconstruction” of our scientific vocabulary using sense-data. The other way he suggests completing the task it to study the psychology behind scientific study in order to determine how sense input develops into scientific output and how we create a theory from that process. Quine believes that only this second proposition is fruitful; this is where Quine and Carnap disagree.

Carnap believed that we should be able to logically construct our theories using our sense-data and logical vocabulary with the help of set theory. For if we could construct our theory into observable sense data, we could use logic and set theory to confirm theoretical claims. However, scientific theories are much more complicated to construct than Carnap had hoped, they tend to include notions that cannot be physically observed and are often theoretically impossible to test. Conceptual theories like Newton’s gravitational force or fluid dynamics assume perfect conditions and impossible conditions to assert their theoretical power. If we could construct a theoretical vocabulary using observation and logic, it would mean that we could be as sure about any logically-proven theory as we are about the very foundations of logic. Carnap later conceded that it would be impossible to reconstruct our theoretical vocabulary using observational sentences and logic because of the nature of theoretical claims.

Epistemological Holism

It is here where Quine introduces one of his reasons of why we cannot rationally reconstruct theoretical claims: epistemological holism. Epistemological holism, also called confirmational holism is the view that says that individual observational statements cannot be empirically proven or disproven, but a group of statements can be confirmed or denied. According to this view, if a theory is proven based on reasonable empirical study, then the entire theory is confirmed. This particular belief implies a tenuous belief relating to the philosophy of mathematics' relationship with empirical science. If the entire theory is confirmed by empirically testing a group of observational and theoretical sentences, one might assume that the mathematical entities typically used in scientific theories are also confirmed as truth. Simply put, Quine’s confirmational holism forces the follower to accept the mathematical components of a confirmed theory as a part of their ontology, a heavy price to pay for any naturalist.

Because we cannot rationally reconstruct a theoretical claim using observational sentences, logic, and set theory, the job of epistemology is to psychologically explain how sense input develops into empirical output. Using this theory, it is safe to assume that obtaining knowledge can only be done is a natural way by means of understanding our sensory stimulations. Quine’s epistemological holism has thus thwarted the reconstruction theory and placed epistemology within psychology as a branch of its own. A final key distinguishing factor of Quine’s naturalism holds that because of epistemologies limitations within psychology, science also resides within epistemology. Without going into too much detail, Quine posits that science and epistemology must fit together within our empirical worldview together because both fields of study are mutually constrained in a sense. This constrained view is one step further than most naturalists are willing to take, and it is also a key aspects of Quine’s naturalistic worldview.

Indispensability Argument (QPA)

Quine’s epistemological holism suggests an ontological commitment to mathematical entities because those entities are indispensable to our best scientific theories. Quine and Putnam discussed the indispensability argument at length, and we will gloss over the important points here to motivate our later claims regarding naturalism’s reconciliation via confirmational holism. The (QPA) argument follows:

The Quine-Putnam Indispensability Argument

  1. We ought to have ontological commitment to all and only the entities that are indispensable to our best scientific theories.
  2. Mathematical entities are indispensable to our best scientific theories.
  3. We ought to have ontological commitment to mathematical entities.

An important first step in understanding this argument is to define dispensability. Field tells us that in order for something to dispensable, it must be both eliminable and the theory must be attractive without unnecessary ontological or theoretical commitment. This doesn’t necessarily mean that the theory has to be more attractive than the original theory, but it has to be attractive. Some empirical markers of attractiveness might be: explanatory power, empirical power/demonstration, simplicity of theory, unifying other scientific theories, etc. Susan Vineberg summarizes a few key points of the indispensability thesis, “Both Quine and Putnam have argued that acceptance of our scientific theories as true forces us to accept abstract mathematical entities as well. The reason stems from the fact that mathematics forms an essential part of many of our scientific theories … since mathematical theory forms an essential part of our well confirmed scientific theories, we have reason to regard the mathematical theory used in these theories as true as well. Furthermore, they claim that the variables in our mathematical theories range over abstract entities and hence their existence is presupposed by the truth of our scientific theories of which mathematics is a part … Thus, to accept the truth of our scientific theories while denying the existence of abstract mathematical objects is simply to fail to accept the consequences of affirming the truth of our scientific theories'. 

Vinebergs quote breaks down the indispensability thesis further to better understand the necessary mathematical commitments. Scientists and philosophers ought to believe in abstract mathematical entities because these entities are indispensable to our best confirmed scientific theories. Without these mathematical entities, a theory would not be able to be confirmed, and/or it would have far less explanatory power. For now, it is important to note that we ought only ontologically accept enough mathematical concepts that are purely indispensable to our best scientific theories.

No Naturalism Via Epistemological Holism

It is here where the indispensability falls under attack from a number of theorists, including Hilary Putnam, Harry Fields, and Penelope Maddy. Each academic position attack against different premises of the argument, with Maddy’s argument undermining a key aspect of epistemological holism related to Quine’s naturalism. To generalize, Maddy claims that epistemological holism is not strong enough to actually require ontological belief in all entities that appear indispensable to our best scientific theories.

Maddy’s key objections in her 1992 paper are related to confirmational holism reconciling naturalism via the first premise of the QPA. She argues primarily that the actual practice of science does not reinforce the holism that the QPA requires to ground naturalistic belief. Her first objection questions the ability of scientists to hold different opinions about the different components of generally accepted scientific theories, while still maintaining the belief in the power of scientific confirmation with regard to the theory. The important thing to note here is the distinction she makes between naturalism and holism, and that scientists often have discriminatory beliefs about scientific methodology and soundness. By highlighting the fact the naturalism supports general scientific practice while holism requires scientists to accept and hold all of the indispensable entities required by the theories, Maddy creates a dichotomy between naturalism and epistemological holism. She believes that we ought to reject the first premise of the QPA because naturalism should take the lead over holism with regard to scientific consensus. We can encourage scientists who have different ontological commitments to well-confirmed theories, and this suggests that the “all” part of the fisrt statement holds on for far too long.

A further objection dovetails from this first objection that requires rejecting the holism of scientific theories. Maddy indicates that when scientists do accept mathematics as part of a theory, they may not be the theory in the proven form, but only in the ideal form. In calculating the mass of certain energies, scientists regularly assume that gravitational force is constant, which is a provable false assumption. Nonetheless, scientists will use whatever mathematics is necessary to complete their science, regardless of the mathematical “truth” behind the theory. The point being made is that holism is battling with scientific practice while purveying comfort to philosophers. Again she makes the point that we ought to reject the first premise of the QPA because of the conflict between naturalism’s scientific respects and epistemological holism’s contradictory oversight. For if we are true to our naturalist tendencies we should agree with working (and successful) scientists. Because of the naturalist slant, it seems that we may not need to accept the “truth” of a mathematical theory because of it’s indispensability purely by means of a proper (and potentially ideal) application of said theory. Through a number of different avenues, Maddy has rejected the first premise of the QPA.  

Overall, by considering that the nature of mathematics is under-fire because of the indispensability arguments, I introduced Maddy’s theory about epistemological holism and answer objects to her theory while making a clarifying claim of my own. The exposition and understanding within is included to support a final claim, that is to question the first proposition of the QPA to show that holism may not completely reconcile Quine’s naturalism. 

07 July 2022
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