The Evolution of Naturalized Epistemology: From Quine to Today

For most of Western philosophy’s history, the question “how do we know what we know?” was treated as something philosophers could answer from an armchair – through pure reason, logical analysis, and abstract reflection. Then, in 1969, W.V. Quine published a short but electrifying essay that challenged this assumption entirely. His argument was straightforward: if centuries of traditional epistemology had failed to deliver a secure foundation for knowledge, perhaps it was time to stop trying – and to let science take over. That provocation gave birth to what we now call naturalized epistemology, one of the most debated and productive shifts in twentieth-century philosophy.

The problem with traditional epistemology 🔗

To understand why Quine’s proposal was so radical, it helps to know what he was reacting against. Traditional epistemology, shaped by René Descartes and later refined into what is called foundationalism, held that all genuine knowledge must rest on certain indubitable foundations – basic beliefs so clear and self-evident that they are immune to doubt. From these foundations, all other knowledge is built upward through logical inference. The Cartesian dream was to achieve the kind of certainty that could defeat skepticism once and for all.

But that dream kept running into hard problems. The most persistent was David Hume’s challenge to induction: how can repeated observations of the past ever logically guarantee conclusions about the future? Philosophers had no satisfying answer. Additionally, the ambitious project of reducing all scientific knowledge to pure logic – a project pursued vigorously by the Vienna Circle of logical empiricists – ended in failure. Mathematics could not be cleanly reduced to logic, and attempts to reconstruct scientific knowledge on purely logical foundations proved untenable. For Quine, these repeated failures were not just accidents – they were symptoms of a deeper flaw in the entire foundationalist enterprise.

Quine’s revolutionary proposal 🔗

Quine’s response, laid out in his landmark 1969 essay Epistemology Naturalized (published in Ontological Relativity and Other Essays), was to abandon the foundationalist project entirely and replace it with an empirical one. The term ‘naturalized epistemology’ was introduced by Quine in this essay, in which he argued that epistemology should be regarded as continuous with, or even part of, natural science. Rather than asking how knowledge should be justified in some timeless, abstract sense, Quine asked how human beings actually acquire knowledge – and proposed that this question be studied like any other natural phenomenon.

In a well-known passage, Quine describes the subject of naturalized epistemology as studying “a natural phenomenon, viz., a physical human subject” who receives sensory input and produces, over time, a description of the three-dimensional external world. In other words, epistemology becomes the empirical study of how a biological organism – equipped with sense organs and a nervous system – builds a picture of reality from the limited data flowing in through perception. This shifts the focus from justification and certainty to knowledge acquisition as a natural process.

Epistemology as a chapter of psychology 🔗

Quine’s most provocative claim was that epistemology “simply falls into place as a chapter of psychology and hence of natural science,” studying how experimental input relates to theoretical output. For Quine, the disciplines of psychology, neuroscience, and linguistics are not merely useful supplements to philosophy – they are its replacements. The goal of establishing how knowledge is justified from first principles is discarded in favor of describing how knowledge actually works in the minds of real people. Evolution, perception, language learning, and neurological processes all become relevant. This position is known as replacement naturalism: the view that traditional epistemology should be abandoned and its questions answered by the natural sciences.

The circularity problem – and Quine’s response 🔗

An obvious objection arises immediately: if we use science to study how we come to know scientific truths, aren’t we reasoning in a circle? Quine acknowledged this. He argued that the appeal to science is not to be dismissed for circularity, since it is the best available option after ruling out traditional philosophical methods for their more serious flaws. In short, circularity is a lesser problem than failure. Traditional epistemology promised to validate science from an external standpoint – and it couldn’t deliver. Quine’s naturalized epistemology makes no such promise; it simply works within science to understand science. This pragmatic tolerance of circularity is one of the most distinctive features of Quine’s philosophical outlook.

The rejection of the analytic-synthetic distinction 🔗

Quine’s turn to naturalism was not an isolated argument. It was connected to one of his earlier and equally influential philosophical moves: the rejection of the analytic-synthetic distinction. Traditionally, philosophers divided all meaningful statements into two types – analytic statements (true by meaning alone, like “all bachelors are unmarried”) and synthetic statements (true by virtue of facts about the world). The logical empiricists relied heavily on this distinction to demarcate scientific claims from metaphysical ones.

In his 1951 essay Two Dogmas of Empiricism, Quine argued that this boundary is not as clean as philosophers assumed. There is no sharp line between what is true “by meaning” and what is true “by fact.” This holistic view of knowledge – where our beliefs form a web in which any element can be revised in light of experience – directly undermined foundationalism. If no belief is entirely immune to revision, there can be no incorrigible foundations. And if there are no foundations, it is unclear how traditional epistemology could maintain any hard distinction between philosophy and science.

Hilary Putnam’s critique: what happened to norms? 🔗

Quine’s proposal attracted both admiration and sharp criticism. Among the most influential critics was Hilary Putnam, one of the most important American philosophers of the twentieth century, who shared Quine’s scientific outlook but found his naturalism too radical in one crucial respect.

Putnam’s central objection was about normativity. Epistemology has always been concerned not just with how people form beliefs, but with how they ought to form them – what counts as good evidence, what makes a belief justified, what distinguishes rational inquiry from mere guessing. Quine’s replacement naturalism, Putnam argued, threatens to eliminate these normative questions altogether, leaving only a purely descriptive account of how belief-formation causally works. Putnam charged that Quine was effectively arguing for “sheer epistemological eliminationism” – abandoning notions of justification, good reason, and warranted assertion.

For Putnam, this was self-defeating. He asked why we should expend mental energy convincing ourselves that no thought is right or wrong beyond being “the verdict of the moment” – a view he saw as self-refuting. If there are no normative standards by which beliefs can be evaluated as better or worse, then science itself cannot claim any special epistemic status. The very project of naturalized epistemology would then lack the normative resources to justify itself. Putnam also worried that a purely descriptive epistemology risked collapsing into a kind of relativism, where any belief, however irrational, becomes acceptable as long as it coheres with a person’s overall worldview.

Putnam’s liberal naturalism 🔗

Putnam did not reject naturalism as such – he rejected its reductive, eliminativist form. In his later work, he embraced what he called liberal naturalism: a position that takes the empirical findings of science seriously while insisting that normative phenomena form an ineluctable part of human experience and cannot be reduced to purely physical or descriptive facts. On this view, the natural sciences are not the only legitimate source of knowledge, and not everything real can be captured in the language of physics or neuroscience. Philosophy retains its own irreducible role in evaluating the norms that govern rational inquiry. This represents a significant softening of Quine’s more aggressive replacement naturalism.

Cooperative naturalism: a middle path 🔗

The debate between Quine’s replacement naturalism and Putnam’s insistence on normativity eventually gave rise to a more moderate position – one that most contemporary philosophers find more defensible. This position is known as cooperative naturalism. Cooperative naturalism holds that while there are evaluative questions to pursue, the empirical results from psychology concerning how individuals actually think and reason are essential and useful for making progress on these evaluative questions. In other words, traditional epistemology cannot be eliminated, but neither can it fully succeed without drawing on the empirical sciences.

The philosopher Alvin Goldman became one of the leading architects of this cooperative approach. Unlike Quine, Goldman retained a traditional focus on questions of justification and developed what he called reliabilism – the view that a belief is justified if it is produced by a cognitive process that reliably leads to true beliefs. This framework draws directly on cognitive science and psychology to evaluate which belief-forming processes are reliable, while still maintaining normative standards for what counts as good epistemology. Goldman and Philip Kitcher applied insights from both the natural and the social sciences to understand knowledge as a simultaneously cognitive and social phenomenon.

Reliabilism and the normative question 🔗

Goldman’s reliabilism is significant because it responds directly to Putnam’s normativity objection without abandoning naturalism. On this view, epistemic justification is a form of instrumental value – it derives from the causal ties between cognitive means and valuable cognitive ends, such as the goal of believing what is true. This means that normative standards are not eliminated but reframed: a belief-forming process is epistemically good insofar as it reliably promotes truth. Cognitive science can tell us which processes are reliable, and philosophy can evaluate whether reliability is the right criterion. Science and philosophy work together rather than one replacing the other.

Where naturalized epistemology stands today 🔗

Since Quine’s original provocation, naturalized epistemology has branched in several directions. Contemporary discussions extend to externalism, experimental philosophy, social epistemology, feminist epistemology, evolutionary epistemology, and debates about epistemic rationality – all of them shaped, in one way or another, by Quine’s challenge to the armchair tradition. Experimental philosophy has brought empirical methods directly into the study of philosophical intuitions, testing whether ordinary people’s judgments about knowledge and justification match the assumptions philosophers have long made. Social epistemology examines how knowledge is acquired and transmitted within communities, institutions, and across the internet – questions that pure armchair reflection could never adequately address.

What has endured from Quine is the core insight that knowledge is a natural phenomenon – something that happens in biological organisms embedded in physical environments – and that understanding it requires more than logical analysis alone. What has evolved, thanks to critics like Putnam and constructive work by thinkers like Goldman, is a richer, more pluralistic version of this insight: one that preserves the normative dimensions of epistemology while remaining open to what the sciences reveal about the human mind.

What do you think? If epistemology must draw on psychology and cognitive science to understand knowledge, does that mean philosophers are simply doing a version of science – or is there still something distinctively philosophical left to do? And if normativity cannot be captured by purely empirical methods, as Putnam argued, where exactly does it come from?

References

1. https://www.rep.routledge.com/articles/thematic/naturalized-epistemology/v-2
2. https://plato.stanford.edu/entries/epistemology-naturalized/
3. https://as.nyu.edu/content/dam/nyu-as/philosophy/documents/faculty-documents/foley/Foley_Quine-Naturalized.pdf
4. https://en.wikipedia.org/wiki/Naturalized_epistemology
5. https://www.hup.harvard.edu/books/9780674659698
6. https://medium.com/@paulaustinmurphy2000/hilary-putnams-why-reason-can-t-be-naturalised-1f729e96a537
7. https://www.independent.org/article/2006/05/18/knowledge-and-naturalism/
8. https://link.springer.com/chapter/10.1007/978-3-030-27041-4_4
9. https://iep.utm.edu/nat-epis/