“Tabula Rasa and the Trouble with Difference: John Locke’s Developmental Theory of the Mind and the History of Disability”

By Julia Baldowski

John Locke’s 1690 piece, An Essay Concerning Human Understanding [3] introduced a theory of mind that profoundly shaped Enlightenment thought, Western pedagogy, and evolving notions of personhood. His assertion that the mind begins as a tabula rasa, or blank slate, upon which experience writes all knowledge, was especially radical. Locke’s framework laid the foundation for later models of education, reason, and moral development. Yet it also established cognitive norms that would marginalize individuals whose minds diverged from the rational ideal. Considering Locke’s legacy within the intellectual history of disability, one cannot ignore how his theory of development contributed to exclusionary systems that pathologized cognitive differences. Locke’s optimism about human perfectibility also contained the seeds of a new form of ableism: one rooted not in divine judgement, but in deviation from developmental expectations. 

Locke’s rejection of innate ideas and his insistence on experience as the sole source of knowledge marked a decisive shift in early modern epistemology. As he famously wrote, “Let us then suppose the mind to be, as we say, white paper, void of all characters, without any ideas” [3]. For Locke, human understanding develops two faculties: sensation, the intake of external impressions. This model opened the door for educational reformers and political philosophers alike to imagine a world in which all individuals, regardless of birth, could be cultivated into rational citizens, provided they were given the appropriate environment and instruction. 

In another essay titled, Some Thoughts Concerning Education from 1693 [4], Locke elaborated on this vision, proposing that character, reason, and self-discipline could be instilled through careful and consistent upbringing. As John Yolton, American historian of philosophy, observed, Locke’s theory of mind “offered a framework within which the capacities of the individual could be evaluated and shaped” [8]. The implications of such a framework were considerable as it was not only descriptive, but prescriptive. The ideal subject was one who progressed predictably and visibly toward rational autonomy. 

Yet, Locke’s developmental optimism rested on a particular teleology, that the goal of mental development was rationality. This had significant ramifications for the emerging Enlightenment discourse on disability. As Anne Waldschmidt, German sociologist, notes, Enlightenment liberalism increasingly defined the ideal citizen as a reasoning, self-governing subject. Within this paradigm, those who could not, or did not, attain rational maturity were tacitly excluded from fully participating in the moral and civic community. 

In earlier periods, disability was often interpreted through theological or symbolic frameworks. Individuals with visible or cognitive differences were perceived as objects of charity, embodiments of divine mystery, or subjects of moral speculation. But the shift toward secular rationalism altered these terms of engagement. Disability, particularly intellectual or developmental disability, began to be understood not as a variation but as a deviation, a failure of the blank slate to develop properly. 

Locke himself did not write extensively about cognitive disability, but his framework facilitated a growing interest in categorizing and managing those who did not follow normative trajectories. Enlightenment-era physicians, educators, and legal theorists increasingly conceptualized disability in terms of cognitive insufficiency, an ontological lack, as David Mitchell and Sharon Snyder put it, defined by the distance from the rational ideal [5]. In this context, the “defective” mind was not just different, but rather it was a failed potential. 

The rise of educational and medical institutions in the eighteenth and nineteenth centuries made these theoretical implications deeply practical. Figures such as French physicians Jean-Marc Gaspard Itard and Edouard Seguin drew directly from Enlightenment developmentalism in their attempts to “civilize” children with intellectual disabilities through sensory training and behavioral conditioning. Their pedagogical experiments, including the well-known work of the aforementioned physicians, were informed by a Lockean belief in the plasticity of the mind. 

However, when such efforts failed to produce rational or communicative outcomes, the individuals in question were increasingly consigned to institutions. As Dr. James W. Trent, Jr. demonstrates in Inventing the Feeble Mind: A History of Intellectual Disability in the United States [6], the inability to conform to developmental expectations became the rationale for systemic exclusion. The language or progress and improvement, so central to Locke’s epistemology, was weaponized to segregate those whose development was deemed incomplete or unsuccessful. Importantly, this was not a return to earlier forms of social ostracization based on superstition or fear. Rather, it was an exclusion grounded in a secular, rationalist framework that presumed education as the baseline for value. Those labeled uneducable disrupted not only pedagogical ambitions but also philosophical assumptions about what it meant to be human.

Contemporary disability studies have mounted a sustained critique of these Enlightenment legacies. Disability studies researcher, Fiona Kumari Campbell, argues that the very concept of “ableism” emerges from the privileging of rationality and autonomy that thinkers like Locke helped institutionalize. In her view, cognitive and bodily norms were not neutral descriptors but prescriptive ideals, used to regulate rights, personhood, and recognition [1]. The neurodiversity movement has similarly pushed back against the notion that all minds should aspire to the same developmental endpoints. From this perspective, Locke’s blank slate becomes a double-edged metaphor: while it implies universal potential, it also enforces a universal standard. As scholar, Nirmala Erevelles, notes, developmental frameworks often obscure the ways in which disability intersects with race, class, and colonialism, presenting exclusion as natural rather than structured [2]. Furthermore, disability scholars have insisted on alternative epistemologies such as ways of knowing and being that do not hinge on logic, productivity, or verbal communications. These perspectives challenge the very foundations of the Lockean subject, calling into question the universality of his developmental model and exposing its limitations in accounting for diverse cognitive experiences. 

John Locke’s theory of the mind as tabula rasa remains a landmark in the history of ideas, offering a powerful vision of educability and human perfectibility. Yet, the same framework that promised emancipation through reason also contributed to a rigid hierarchy of cognitive value. By linking personhood to the successful development of rational faculties, Locke’s legacy has played a subtle, yet profound, role in shaping modern constructions of disability. Historians and theorists of disability continue to grapple with this inheritance. It is not enough to recognize Locke’s influence on educational or political thought. We must also reckon with how his developmental model set the terms for who counts as fully human. In doing so, we illuminate the deep historical roots of ableism and open space for more inclusive conceptions of knowledge, agency, and human variation. 

References

1. Campbell, Fiona Kumari. Contours of Ableism: The Production of Disability and Abledness. New York: Palgrave Macmillan, 2009.

2. Erevelles, Nirmala. Disability and Difference in Global Contexts: Enabling a Transformative Body Politic. New York: Palgrave Macmillan, 2011.

3. Locke, John. An Essay Concerning Human Understanding. London: Thomas Basset, 1690.

4. Locke, John, 1632-1704. Some Thoughts Concerning Education. Oxford : New York :Clarendon Press ; Oxford University Press, 1989.

5. Mitchell, David T., and Sharon L. Snyder. Cultural Locations of Disability. Chicago: University of Chicago Press, 2006.

6. Trent Jr., James W. Inventing the Feeble Mind: A History of Mental Retardation in the United States. Berkeley: University of California Press, 1994.

7. Waldschmidt, Anne. “Disability Studies as a New Humanities.” Disability Studies Quarterly 37, no. 3 (2017). https://dsq-sds.org.

8. Yolton, John W. Locke and the Compass of Human Understanding: A Selective Commentary on the “Essay”. Cambridge: Cambridge University Press, 1970.