Psychedelics Favour Understanding Rather Than Knowledge


Process of Discovery
Process of Justification
Epistemic Benefits
Epistemic Standards

How to Cite

Fink, S. B. (2022). Psychedelics Favour Understanding Rather Than Knowledge. Philosophy and the Mind Sciences, 3.


Chris Letheby argues in Philosophy of Psychedelics that psychedelics and knowledge are compatible. Psychedelics may cause new mental states, some of which can be states of knowledge. But the influence of psychedelics is largely psychological, and not all psychological processes are epistemic. So I want to build on the distinction between processes of discovery and processes of justification to criticise some aspects of Letheby’s epistemology of psychedelics. Unarguably, psychedelics can elicit processes of discovery. Yet, I hold, they can hardly contribute either to the epistemic success (i.e., truth, veridicality, aptness, skillfulness, etc.) of a mental state or to processes of justification. As these are central for a mental state to be a state of knowledge and are largely uninfluenced by psychedelics, the contributions of psychedelics to knowledge are rather indirect than direct: The heavy epistemic lifting—what turns a mental state into a state of knowledge—is, in its epistemic aspects, independent of any influence of psychedelics on our psyche. Positively, while the mechanisms that Letheby points to need not be associated with knowledge, they do provide crucial epistemic benefits if they are associated with understanding. Reading them as facilitating understanding covers also those cases where truth or justification is missing and thereby provides a broader picture of the epistemic contributions of psychedelics.


Aquinas, T. (1259-65). Summa contra gentiles. Vat. lat. 9850.

Carhart-Harris, R. L, & Friston, K. J. (2019). REBUS and the anarchic brain: Toward a unified model of the brain action of psychedelics. Pharmacological Reviews, 71(3), 316–344.

Carhart-Harris, R. L., Kaelen, M., Whalley, M., Bolstridge, M., Feilding, A., & Nutt, D. J. (2015). LSD enhances suggestibility in healthy volunteers. Psychopharmacology, 232(4), 785–794.

Davidson, D. (1973). Radical interpretation. Dialectica, 27(1), 314–328.

Galilei, G. (1638). Discorsi. Leida, Apresso gli Elsevirii.

Goldman, A. (1979). What is justified belief? In G. Pappas (Ed.), Justification and knowledge (pp. 1–25). Boston: D. Reidel.

Goldman, A., & Beddor, B. (2021). Reliabilist Epistemology. In E. N. Zalta (Ed.), The Stanford encyclopedia of philosophy (Summer 2021).; Metaphysics Research Lab, Stanford University.

Hoyningen-Huene, P. (1986). Context of discovery and context of justification. Studies in History and Philosophy of Science Part A, 18(4), 501–515.

Huxley, A. (1954). The Doors of Perception. Chatto & Windus.

Jopling, D. A. (2001). Placebo insight: The rationality of insight-oriented psychotherapy. Journal of Clinical Psychology, 57(1), 19–36.;2-Z

Letheby, C. (2021). Philosophy of Psychedelics. Oxford, UK: Oxford University Press.

Marr, D. (1982). Vision. W. H. Freeman.

Preller, K. H., Burt, J. B., Ji, J. L., Schleifer, C. H., Adkinson, B. D., Stämpfli, P., et al. (2018). Changes in global and thalamic brain connectivity in LSD-induced altered states of consciousness are attributable to the 5-HT2A receptor. Elife, 7, e35082.

Quine, W. V. (1969). Epistemology naturalized. In J. Kim & E. Sosa (Eds.) Ontological Relativity and Other Essays. New York: Columbia University Press.

Williams, J. N. (1982). Believing the self-contradictory. American Philosophical Quarterly, 19(3), 279–285.

Zednik, C., & Jäkel, F. (2016). Bayesian reverse-engineering considered as a research strategy for cognitive science. Synthese, 193(12), 3951–3985.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Copyright (c) 2022 Sascha Benjamin Fink