Ernest Sosa

1. Introduction

Ernest Sosa (b. 1940) is widely regarded as one of the central architects of contemporary analytic epistemology. His work is best known for developing virtue epistemology, an approach that explains knowledge in terms of the intellectual excellences or competences of agents rather than solely in terms of properties of individual beliefs. Within this framework, Sosa has advanced a performance-theoretic conception of knowing, analyzing beliefs on analogy with skilled actions such as archery or athletic performance.

A unifying theme of Sosa’s epistemology is the idea that knowledge is a kind of achievement: a true belief that derives from the agent’s reliable cognitive capacities functioning properly in appropriate conditions. This idea is captured in his influential AAA model, which evaluates performances—including cognitive ones—according to their accuracy, adroitness, and aptness. For Sosa, knowledge is an apt belief: a belief that is accurate because adroit, in a way creditable to the believer’s epistemic competence.

Sosa has also introduced a widely discussed distinction between animal knowledge and reflective knowledge, corresponding to different grades of epistemic achievement. This distinction, together with his performance-theoretic account, informs his responses to skepticism, his analysis of epistemic luck, and his treatment of epistemic normativity and risk.

Beyond substantive epistemology, Sosa has been a major figure in metaphilosophy, defending the role of intuitions in philosophical practice and articulating a model of philosophy as reflective evaluation of our cognitive competences. His writings, teaching, and editorial work have significantly shaped the agenda and methods of late 20th- and early 21st-century epistemology.

2. Life and Historical Context

Ernest Sosa was born on 17 June 1940 in Caguas, Puerto Rico. He moved to the mainland United States for higher education and completed his PhD in philosophy at the University of Pittsburgh in 1964, a department then prominent in analytic philosophy and the philosophy of science. This training placed him within the emerging post-positivist landscape, where questions about realism, justification, and the limits of empiricism were central.

Immediately after his PhD, Sosa joined the philosophy department at Brown University (1964). Brown became, in part through his presence, a major hub for analytic epistemology in the 1970s and 1980s, when debates over foundationalism, coherentism, and the nature of justification were reshaping the field. Sosa’s early work on the structure of knowledge arose in this context of intensive discussion about internalism, externalism, and the legacy of logical empiricism.

In 2005, Sosa moved to Rutgers University, another leading center for analytic philosophy, at a time when epistemology was increasingly connected with philosophy of mind, cognitive science, and ethics. His shift corresponded with the consolidation of virtue epistemology as a major approach and the rise of new challenges such as experimental philosophy, naturalized epistemology, and social epistemology.

Sosa’s career thus spans key transitions in late 20th-century analytic philosophy:

3. Intellectual Development

Sosa’s intellectual trajectory is often described in phases that track both shifts in his focus and broader developments in epistemology.

Formative Training and Early Analytic Orientation

Educated at Pittsburgh during the 1960s, Sosa absorbed the formal and argumentative rigor characteristic of mid-century analytic philosophy. His early work engaged standard issues in epistemology and metaphysics—such as realism and the analysis of knowledge—within a broadly traditional framework that emphasized justification, evidence, and conceptual analysis.

Structural Epistemology and the Raft–Pyramid Debate

In the 1970s and 1980s, Sosa turned to the structure of justification, most famously in “The Raft and the Pyramid: Coherence versus Foundations in the Theory of Knowledge” (1980). Here he used the metaphors of a pyramid (foundationalism) and a raft (coherentism) to organize and critique competing views. This period consolidated his role as a leading epistemologist and laid groundwork for an agent-centered perspective, as he explored how systems of belief can be stably and non-arbitrarily justified.

Founding and Systematizing Virtue Epistemology

From the late 1980s into the 2000s, Sosa became a principal architect of virtue epistemology. Essays later collected in Knowledge in Perspective (1991) introduced key notions, including epistemic competences and the distinction between animal and reflective knowledge. In A Virtue Epistemology, Vol. I (2007) and Vol. II (2009), he systematized these ideas, presenting the AAA model and a general performance-based theory of knowledge.

Performance-Theoretic Epistemology and Metaphilosophy

In the 2000s and 2010s, especially in Knowing Full Well (2011) and Judgment and Agency (2015), Sosa refined his performance-theoretic approach, emphasizing risk, normativity, and the grades of epistemic achievement. In parallel, he engaged in metaphilosophical debates, defending the evidential role of intuitions and proposing that philosophical inquiry itself can be understood as the reflective exercise of cognitive competences. This phase integrates his earlier epistemological structures into a broader picture of intellectual agency.

4. Major Works and Central Texts

Sosa’s contributions are spread across numerous articles and several influential books. The following overview highlights central texts and their primary themes:

Key Themes Across the Corpus

1. Virtue and Competence: Many essays and books articulate epistemic virtues as stable competences that ground knowledge.
2. Grades of Knowledge: Knowledge in Perspective and the Virtue Epistemology volumes develop the distinction between animal and reflective knowledge.
3. Performance Normativity: Knowing Full Well and Judgment and Agency connect epistemic evaluation with general norms for successful performance under risk.
4. Methodology: Various essays (often reprinted in Knowledge in Perspective) address intuitions, reflective equilibrium, and the nature of philosophical evidence.

Primary sources often cited in discussions of Sosa’s epistemology include his definitions of apt belief and his canonical formulations of animal and reflective knowledge.

5. Core Ideas: Virtue and Performance in Epistemology

At the center of Sosa’s epistemology is the claim that knowledge is a species of successful performance. Believing is treated analogously to skilled activities—such as archery—evaluated by how well they meet certain standards.

The AAA Model and Apt Belief

Sosa’s AAA model distinguishes three dimensions of performance:

On this view, knowledge = apt belief. A true belief that is correct merely by luck is accurate but not apt; it lacks the appropriate credit to the agent’s competence.

Virtue Epistemology and Epistemic Competence

Sosa characterizes epistemic competences as stable, reliable dispositions—such as perceptual acuity, memory, and sound inference—that tend to produce true beliefs in suitable conditions. His virtue epistemology is typically classified as a reliabilist virtue theory, since the relevant virtues are primarily understood in terms of reliable functioning rather than, for example, intellectual character traits (though Sosa acknowledges character virtues as related).

Proponents of Sosa’s approach emphasize its capacity to:

• explain why knowledge is more valuable than mere true belief (it is an achievement);
• locate epistemic evaluation in agents rather than isolated beliefs;
• integrate externalist reliability with internalist norms of responsible belief.

Critics have questioned, among other points, whether all knowledge genuinely involves achievement, whether the performance analogy can handle complex social epistemic phenomena, and how precisely aptness should be analyzed in probabilistic or high-risk environments. Alternative virtue epistemologies, such as those emphasizing intellectual character traits, offer different accounts of the role of virtue in knowledge, sometimes contrasting their more “character-based” focus with Sosa’s “competence-based” performance model.

6. Animal and Reflective Knowledge

Sosa’s distinction between animal knowledge and reflective knowledge introduces a hierarchical structure to epistemic achievement.

Animal Knowledge

Animal knowledge is first-order knowledge grounded in reliable competence without requiring higher-order reflection. For Sosa, an agent has animal knowledge when:

• their belief is apt (accurate because adroit);
• the competence operates in appropriate conditions;
• no special reflective understanding of that competence is needed.

Typical examples involve ordinary perceptual beliefs formed in normal circumstances. The focus is on the reliability of the cognitive system, not the agent’s appreciation of that reliability.

Reflective Knowledge

Reflective knowledge adds a further layer: a kind of second-order endorsement or understanding of one’s first-order epistemic situation. Roughly, an agent has reflective knowledge when:

• they enjoy animal knowledge that p;
• they have an appropriate, competently formed perspective on the reliability and status of their belief that p (for instance, that it arises from trustworthy perception under good conditions);
• the higher-order perspective itself meets standards of aptness.

Sosa sometimes describes this as knowing that one knows, where the “that one knows” component is itself grounded in competences dealing with higher-order epistemic evaluation.

Significance and Debates

Proponents hold that the animal/reflective distinction:

• clarifies the difference between everyday knowledge and more philosophically robust forms of knowing;
• allows a nuanced response to skepticism by conceding possible limits on reflective knowledge while preserving widespread animal knowledge;
• illuminates epistemic responsibilities associated with self-assessment and intellectual autonomy.

Critics have raised questions about:

• whether the higher-order requirement for reflective knowledge threatens to lead to regress;
• how sharp the boundary between animal and reflective grades really is;
• whether some skeptical challenges target animal knowledge as well, thereby limiting the distinction’s explanatory power.

Alternative views propose different gradations of epistemic status or reject higher-order requirements, but Sosa’s two-tier model has become a standard reference point in discussions of epistemic levels.

7. Methodology and Metaphilosophy

Sosa has made influential contributions to debates about how philosophy, and epistemology in particular, should be conducted.

Intuitions and Philosophical Evidence

Sosa defends a positive, though fallibilist, role for philosophical intuitions. He suggests that intuitions—such as those elicited by Gettier cases—are not arbitrary reactions but manifestations of underlying cognitive competences that guide our classificatory judgments.

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“Our intuitions, properly disciplined and reflectively evaluated, are not arbitrary data but expressions of the very competences we seek to understand in philosophical theorizing.”

— Ernest Sosa, Knowledge in Perspective

On this view, intuitions function as first-pass data that demand critical scrutiny and calibration within an overall theoretical framework, rather than as incorrigible foundations.

Critics, including some experimental philosophers, have argued that cross-cultural and demographic variation in intuitions undermines their evidential status. Sosa responds by treating such findings as data about the reliability and domains of our competences, not as reasons to abandon intuition-based methodology altogether.

Epistemology as Theory of Performances

Metaphilosophically, Sosa proposes that epistemology is best understood as the theory of cognitive performances—their risks, norms, and excellences—rather than a mere catalog of propositional attitudes. This aligns epistemology with a broader theory of agency, emphasizing:

• norm-guided evaluation (success vs failure, apt vs inapt);
• the role of risk in assessing achievement;
• the centrality of intellectual virtues and competences.

Some commentators have welcomed this as integrating epistemology with ethics and action theory, while others worry that the performance model may downplay traditional concerns about justification, evidence, or doxastic control.

Sosa also employs a form of reflective equilibrium, aiming to balance intuitions, theoretical virtues, and background knowledge in constructing epistemological theories, while acknowledging the revisability of any element in light of improved understanding.

8. Responses to Skepticism and Epistemic Luck

Sosa’s virtue-theoretic framework is designed in part to address skepticism and epistemic luck by reconceiving knowledge as apt performance under risk.

Skepticism and Grades of Knowledge

Using the animal/reflective distinction, Sosa proposes that skeptical arguments often challenge our possession of reflective knowledge (knowledge that one knows) rather than undermining ordinary animal knowledge. On his view, agents can still have apt perceptual beliefs about the external world even if they cannot definitively rule out radical scenarios (e.g., brains in vats) at the reflective level.

His performance model suggests that what matters for knowledge is that:

• the belief is produced by a competence functioning well in its normal environment;
• remote skeptical possibilities do not interfere with the relevant reliability.

Some critics argue that this response does not fully engage with skepticism about animal knowledge or about the very reliability of our competences, while supporters hold that it preserves common-sense epistemic practices without dismissing skeptical reasoning as meaningless.

Epistemic Luck and Aptness

Sosa’s analysis of epistemic luck centers on the idea that not all luck is incompatible with knowledge. A belief can be accurate by luck yet not apt, in which case it fails to be knowledge. By contrast, knowledge can involve permissible luck (e.g., luck that one’s competence is not defeated by an unusual circumstance) so long as the belief’s truth is still primarily attributable to the agent’s competence.

Gettier-style cases illustrate beliefs that are:

• accurate (true),
• adroit (competently formed in some respects),
• but not apt (their truth is not because of the competence).

Sosa’s framework classifies these as non-knowledge. Critics question whether aptness fully captures all problematic forms of luck, especially in cases of environmental luck or lottery-like uncertainty. Alternative accounts—such as safety and sensitivity theories—offer different criteria, and ongoing debates compare their handling of similar cases with Sosa’s aptness condition.

9. Impact on Contemporary Epistemology and Related Fields

Sosa’s work has had extensive influence across multiple areas of philosophy, particularly within epistemology but also beyond.

within Epistemology

His virtue epistemology helped reorient the field from analyses of “justified true belief + X” toward an agent-centered perspective. Subsequent theorists—both reliabilist and responsibilist virtue epistemologists—have developed, adapted, or criticized his competence-based approach. The AAA model is now a standard tool in discussions of achievement, epistemic value, and the role of luck.

Sosa’s distinctions among animal, reflective, and sometimes further refined grades of knowledge have influenced debates about higher-order evidence, epistemic justification, and the nature of epistemic responsibility. His responses to skepticism are frequently discussed alongside alternative externalist, contextualist, and pragmatic strategies.

Connections to Other Fields

Some commentators praise Sosa for offering a unifying, normatively rich framework; others contend that his focus on individual competence needs supplementation to address social power, testimony, and structural epistemic injustices. Nevertheless, his concepts and distinctions remain integral reference points in current theorizing.

10. Legacy and Historical Significance

Sosa’s legacy is often framed in terms of his role in reshaping the landscape of analytic epistemology from the late 20th century onward.

Position in the History of Epistemology

Historically, Sosa is situated after classical foundationalist/coherentist debates and after the initial rise of reliabilism. He is frequently credited with:

• integrating reliabilist externalism into a broader, agent-focused theory of intellectual virtue;
• introducing a structured account of grades of knowledge that refines traditional conceptions;
• contributing metaphors (such as the raft and pyramid) that became touchstones in teaching and research.

His work is often mentioned alongside that of other virtue epistemologists, such as Linda Zagzebski and John Greco, but is distinguished by its emphasis on performance and competence rather than primarily on character traits.

Institutional and Disciplinary Influence

As a long-serving professor at Brown and later Rutgers, and as an editor and organizer, Sosa played a formative role in establishing epistemology as a central, highly technical subfield of analytic philosophy. Many leading contemporary epistemologists cite his work as a major influence on their own.

Ongoing Assessment

Scholars assess Sosa’s historical significance along several dimensions:

• Systematic impact: His framework for understanding knowledge as apt belief continues to structure debates on knowledge, luck, and normativity.
• Methodological impact: His defense of intuitions and competence-based metaphilosophy remains central in discussions about the nature of philosophical inquiry.
• Critical engagement: Persistent critiques—regarding the scope of performance theory, the individual focus of his virtues, or the sufficiency of aptness in handling luck—have generated a large secondary literature.

While interpretations differ about how enduring particular components of his theory will be, there is broad agreement that Sosa’s work marks a major chapter in the evolution of epistemology, influencing both its technical development and its self-understanding as a discipline.