Skip to main content
SpringerLink
Log in

“The Essential Differentiae of Things are Unknown to Us”: Thomas Aquinas on the Limits of the Knowability of Natural Substances

  • Chapter
  • First Online:
Metaphysics Through Semantics: The Philosophical Recovery of the Medieval Mind

  • 178 Accesses

Abstract

Thomas Aquinas is often presented as a philosopher with a realist and optimistic attitude toward human knowledge. This is essentially true. Nevertheless, there are texts where Aquinas underscores the limits of our knowledge of natural things. For example, he states that we arrive at knowing and naming the substance of a thing only through knowing its accidents. Aquinas makes three main claims about this process: first, the essential principles of natural things are unknown to us; second, the accidents of a thing give a great contribution to the knowledge of what a thing is; third, we impose names on things moving from their accidents. Such claims may be read as introducing a skeptical concern. On the contrary, they express a form of phenomenal realism, which Aquinas reconciles with representationalism in knowledge.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

Log in via an institution
Chapter
USD 29.95
Price excludes VAT (USA)
  • Available as PDF
  • Read on any device
  • Instant download
  • Own it forever
eBook
USD 109.00
Price excludes VAT (USA)
  • Available as EPUB and PDF
  • Read on any device
  • Instant download
  • Own it forever
Hardcover Book
USD 139.99
Price excludes VAT (USA)
  • Durable hardcover edition
  • Dispatched in 3 to 5 business days
  • Free shipping worldwide - see info

Tax calculation will be finalised at checkout

Purchases are for personal use only

Institutional subscriptions

Notes

  1. 1.

    The representationalist interpretation of Aquinas’s theory of intellective knowledge is a highly debated issue. For arguments in favour, see, e.g., Panaccio 2001; for arguments against, see Perler 2000; Baltuta 2013. On Aquinas’s representationalism, see also Brower and Brower-Toland 2008, and Klima 2011. Discussions have especially concerned the nature of intelligible species and the evolution of Aquinas’s position on it. For a discussion of this notion and further bibliographical references, see Spruit 1994–1995; D’Onofrio 2008; Scarpelli Cory 2020.

  2. 2.

    See De anima, I, 1, 402b16–403a2.

  3. 3.

    See Aquinas 1926, 155 (Summa contra gentiles, III, c. 56) [Hereafter referred to as SCG.]

  4. 4.

    See Scriptum super libros Sententiarum, I, d. 44, q. 11, a. 2, a. 2, q.la 2. [Hereafter referred to as Sent.] For a chronology of Aquinas’s life and works, see Porro 2016.

  5. 5.

    See Aquinas 1970a, 31, 102–111 (Quaestiones de veritate, q. 1, a. 10) [Hereafter referred to as Q. de ver.]

  6. 6.

    See Aquinas 1970a, 31, 111–127. In the Commentary on the Sentences Aquinas notes that I can have a true or a false apprehension of a thing, and that both depend on what externally appears of that thing. In both cases, I make inferences about the thing moving from those appearances. See Sent., I, d. 19, q. 5, a. 1. On this, see also Expositio libri Peryermenias, I, c. 3.

  7. 7.

    On orichalcum’s properties of producing rust and inducing nausea, and hence on the prohibition of making the Eucharistic chalice out of orichalcum, see Sent., IV, d. 13, q. 1, a. 2, q.la 5, ad 4, and Summa theologiae, III, q. 83, a. 3, ad 6. [Hereafter referred to as ST]

  8. 8.

    See Aquinas 1984, 7, 247–273 (Sentencia libri De anima, I. c. 1). [Hereafter referred to as Sent. De an.]

  9. 9.

    See Aquinas 1964, 317, n. 1257–1259 (Expositio in XII libros Metaphysicorum Aristotelis, VII, lec. 1) [Hereafter referred to as Exp. Met.]

  10. 10.

    On this principle, see Reynolds 2001; Klima 2002; Pasnau 2007. On the issue of the knowability of substances in the age of Aquinas, see also Noone 2011.

  11. 11.

    See Averroes 1562, 212vbM–213raA (Commentarium in XIIII libros Metaphysicorum Aristotelis, VIII, t.c. 5). On this, see Aquinas 1989, 222, ad lin. 122 (Expositio libri Posteriorum, II, c. 13). [Hereafter cited as Exp. Post.] See there for a complete list of the texts where this dictum recurs.

  12. 12.

    See, e.g., Aquinas 1976, 379, 72–84 (De ente et essentia, c. 5). See also Sent., II, d. 3, q. 1, a. 6; II, d. 35, q. 1, a. 2, ad 3; IV, d. 14, q. 1, a. 1, a.la 6, ad 1; IV, d. 44, q. 2, a. 1, q.la 1, ad 1; Q. de ver., q. 4, a. 1, ad 8; Quaestiones de potentia, q. 9, a. 2, ad 5. [Hereafter referred to as Q. de pot.] In ST, I, q. 29, a. 1, ad 3, Aquinas appears to distinguish two cases. He says that the essential principles are unknown to us or even are unnamed (“substantiales differentiae non sunt nobis notae, vel etiam nominatae non sunt”). It is not clear if the text of the Summa witnesses a supplementary note introducing a disjunction of cases or simply, as is more probable, an overlap between not knowing and not naming the essential differentiae (in this respect, note that one ms., the Vatic. Ottob. 206, only has “vel etiam nominatae”). In the Q. de pot., q. 9, a. 2, ad 5, the two cases are posed in coordination (“ignotae […] et innominatae”).

  13. 13.

    See, e.g., ST, I, q. 77, a. 1, ad 7; Quaestio de spiritualibus creaturis, a. 11, ad 3. [Hereafter referred to as Q. de spir. Creat.]

  14. 14.

    See, e.g., Aquinas 1989, 222, 118–122 (Exp. Post., II, c. 13). See also Exp. Met., VII, lec. 12.

  15. 15.

    In the wake of Aristotle, Aquinas distinguishes between nominal and real definitions (approximately, between definitions expressing what nouns signify and definitions expressing what things are). I do not linger on such a distinction here. For my argument, the only important thing is that in the case of the Aristotelian dictum only real definitions are concerned. For more on such a distinction, see Aquinas’s Commentary on the Posterior Analytics. See Aquinas 1970b.

  16. 16.

    See De ente et essentia, c. 5 (see above, note 12). See also Q. de spir. creat., a. 11, ad 3.

  17. 17.

    See Sent., IV, d. 44, q. 2, a. 1, q.la 1, ad 1.

  18. 18.

    See Aquinas 1929, 104 (Sent., II, d. 3, q. 1, a. 6): “Unde possunt plures differentiae pro specificis assignari, secundum plures proprietates rerum differentium specie, ex essentialibus differentiis causatas; quarum tamen istae melius assignantur quae priores sunt, quasi essentialibus differentiis propinquiores.”

  19. 19.

    See, e.g., Sent., IV, d. 44, q. 2, a. 1, q.la 1, ad 1.

  20. 20.

    See, e.g., Sent., I, d. 25, q. 1, a. 1, ad 8; III, d. 26, q. 1, a. 1, ad 3; IV, d. 27, q. 1, a. 1, q.la 2, ad 2; ST, I-II, q. 49, a. 2, ad 3; Q. de pot., q. 9, a. 2, ad 5; Expositio in librum De generatione, I, lec. 8.

  21. 21.

    See De ente et essentia, c. 5 (see above, note 13); Sent. De an., I, c. 1 (see above, note 9).

  22. 22.

    Aquinas seems to suggest this when he explains that Aristotle indicated ‘cold’ and ‘warm’, which are accidental differentiae, as the differentiae in the definition of earth and fire, respectively, because we do not know their essential differentiae. See, e.g., Expositio in librum primum De generatione et corruptione Aristotelis, lec. 8. Also ST, I, q. 29, a. 1, ad 3.

  23. 23.

    See, e.g., ST, I, q. 13, a. 8. For this interpretation, see Pasnau 2002, 143ff.; also Pasnau 2007.

  24. 24.

    On this, see Wippel 2000, 511, n. 39; 542.

  25. 25.

    See Q. de spir. creat., a. 11, ad 3.

  26. 26.

    See Q. de ver., q. 10, a. 1, ad 6; also ST, I, q. 77, a. 1, ad 7; Quaestiones de anima, q. 12, ad 8.

  27. 27.

    See Aquinas 1976, 374, 10–13 (De ente et essentia, c. 3).

  28. 28.

    See, e.g., Q. de ver., q. 4, a. 1, ad 8.

  29. 29.

    For an introduction to Aquinas’s theory of signification, see Buersmeyer 1987; Ashworth 1991; also Pini 1999. For an assessment of the role played by semantics in Aquinas’s metaphysics, see Klima 1996.

  30. 30.

    See, e.g., Pieper 1953.

  31. 31.

    On this, see also Haldane 1988.

  32. 32.

    On Scotus’s criticism of Aquinas’s doctrine of essence, see Pini 2003.

  33. 33.

    For the etymology of the word ‘intellect’ (intellectus), see, e.g., Q. de ver., q. 1, a. 12; ST, II–II, q. 8, a. 1.

  34. 34.

    See Aquinas 1964, 273, n. 504 (Exp. Met., V, lec. 19), for the Latin texts. English translation is from Aquinas 1961, 338.

  35. 35.

    See Aquinas 1964, 274, n. 1048 (Exp. Met., V, lec. 19); Aquinas 1961, 339.

  36. 36.

    For further details on Aquinas’s account of definition, see Galluzzo 2001.

  37. 37.

    For a recent assessment of Aquinas’s skepticism, see Klima 2009.

  38. 38.

    Aquinas equates intelligible species and essence in Quodlibet VIII, q. 2, a. 2. This equation has been greatly discussed in the literature. It is not possible to dwell on this aspect here. For details, see Pini 2004. On the topic, see also Galluzzo 2004; Amerini 2004.

Bibliography

  • Amerini, Fabrizio. 2004. Thomas Aquinas, Alexander of Alexandria, and Paul of Venice on the nature of essence. Documenti e studi sulla tradizione filosofica medievale 15: 541–589.

    Google Scholar 

  • Aquinas, Thomas. 1926. Summa contra Gentiles. In Sancti Thomae Aquinatis Opera omnia, t. XIV. Rome: Typis Riccardi Garroni.

    Google Scholar 

  • ———. 1929. In Scriptum super libros Sententiarum, ed. Pierre Mandonnet, 2 vols ed. Paris: Lethielleux.

    Google Scholar 

  • ———. 1961. Commentary on the metaphysics. Trans. J.P. Rowan. Chicago: Henry Regnery Company.

    Google Scholar 

  • ———. 1964. In Expositio in XII libros Metaphysicorum Aristotelis, ed. Raymundus Spiazzi. Turin/Rome, Marietti.

    Google Scholar 

  • ———. 1970a. Quaestiones de veritate, ed. Antoine Dondaine. In Sancti Thomae de Aquino Opera omnia, t. XXII/I-2. Rome: Ad Sanctae Sabinae.

    Google Scholar 

  • ———. 1970b. Commentary on the posterior analytics of Aristotle. Trans. F.R. Larcher. Albany: Magi Books, Inc.

    Google Scholar 

  • ———. 1976. De ente et essentia, ed. Hyacinthe-François Dondaine. In Sancti Thomae de Aquino Opera omnia, t. XLIII. Rome: Editori di San Tommaso.

    Google Scholar 

  • ———. 1984. Sentencia libri De anima, ed. René-Antoine Gauthier. In Sancti Thomae de Aquino Opera omnia, t. XLV/1. Rome/Paris: Commissio Leonina/J. Vrin.

    Google Scholar 

  • ———. 1989. Expositio libri Posteriorum, ed. René-Antoine Gauthier. In Sancti Thomae de Aquino Opera omnia, t. I 2. Rome/Paris: Commissio Leonina/J. Vrin.

    Google Scholar 

  • Ashworth, E. Jennifer. 1991. Signification and modes of signifying in thirteenth-century logic: A preface to Aquinas on analogy. Medieval Philosophy and Theology 1: 39–67.

    Article  Google Scholar 

  • Averroes. 1562. Commentarium in Libros Metaphysicorum. Venice: apud Iunctas, t. VIII.

    Google Scholar 

  • Baltuta, Elena. 2013. Aquinas on intellectual cognition: The case of intelligible species. Philosophia 41 (3): 589–602.

    Article  Google Scholar 

  • Brower, Jeffrey E., and Susan Brower–Toland. 2008. Aquinas on mental representation: Concepts and intentionality. Philosophical Review 117 (2): 193–243.

    Article  Google Scholar 

  • Buersmeyer, Keith. 1987. Aquinas on the ‘modi significandi’. The Modern Schoolman 64 (2): 73–95.

    Article  Google Scholar 

  • D’Onofrio, Sandro R. 2008. Aquinas as representationalist: The ontology of the species intelligibilis. Ph.D. Dissertation, State University of New York at Buffalo.

    Google Scholar 

  • Galluzzo, Gabriele. 2001. Il problema dell’oggetto della definizione nel commento di Tommaso d’Aquino a ‘Metafisica’ Z 10–11. Documenti e studi sulla tradizione filosofica medievale 12: 417–465.

    Google Scholar 

  • ———. 2004. Aquinas on common nature and universals. Recherches de théologie et philosophie médiévales 71 (3): 131–171.

    Article  Google Scholar 

  • Haldane, John. 1988. San Tommaso e Putnam: realismo ontologico e realismo epistemologico. Intersezioni 8: 171–188.

    Google Scholar 

  • Kenny, Anthony. 1993. Aquinas on mind. London/New York: Routledge.

    Google Scholar 

  • Klima, Gyula. 1996. The semantic principles underlying saint Thomas Aquinas’s metaphysics of being. Medieval Philosophy and Theology 5: 87–141.

    Article  Google Scholar 

  • ———. 2002. Contemporary ‘essentialism’ vs. Aristotelian essentialism. In Mind, metaphysics, and value in the Thomistic and analytical traditions, ed. John Haldane, 175–194. Notre Dame: University of Notre Dame Press.

    Google Scholar 

  • ———. 2009. The anti-skepticism of John Buridan and Thomas Aquinas: Putting skeptics in their place versus stopping them in their tracks. In Rethinking the history of skepticism: The missing medieval background, ed. Henrik Lagerlund, 145–170. Leiden/Boston: Brill.

    Chapter  Google Scholar 

  • ———. 2011. Intentional transfer in Averroes, indifference of nature in Avicenna, and the representationalism of Aquinas. In Universal representation, and the ontology of individuation, Proceedings of the Society for Medieval Logic and Metaphysics Volume 5, ed. Alexander W. Hall and Gyula Klima, 45–52. Newcastle upon Tyne: Cambridge Scholars Publishing.

    Google Scholar 

  • Kretzmann, Norman J. 1993. Aquinas’s philosophy of mind. Philosophical Topics 20 (2): 85–90.

    Google Scholar 

  • MacDonald, Scott. 1993. Theory of knowledge. In The Cambridge companion to Aquinas, ed. Norman J. Kretzmann and Eleonore Stump, 160–195. Cambridge: Cambridge University Press.

    Chapter  Google Scholar 

  • Noone, Timothy B. 2011. The problem of the knowability of substance: The discussion from Eustachius of Arras to Vital du Four. In Philosophy and theology in the middle ages: A tribute to Stephen F. Brown, ed. Kent Emery, Russell L. Friedman, and Andreas Speer, 63–90. Leiden/Boston: Brill.

    Chapter  Google Scholar 

  • Panaccio, Claude. 2001. Aquinas on intellectual representation. In Ancient and medieval theories of intentionality, ed. Dominik Perler, 185–201. Leiden: Brill.

    Chapter  Google Scholar 

  • Pasnau, Robert. 1997. Theories of cognition in the later middle ages. Cambridge: Cambridge University Press.

    Google Scholar 

  • ———. 2002. Thomas Aquinas on human nature. A philosophical study of Summa theologiae 1a 75–89. Cambridge: Cambridge University Press.

    Google Scholar 

  • ———. 2007. Abstract truth in Thomas Aquinas. In Representation and objects of thought in medieval philosophy, ed. Henrik Lagerlund, 33–63. Aldershot: Ashgate.

    Google Scholar 

  • Perler, Dominik. 2000. Essentialism and direct realism: Some late medieval perspectives. Topoi 19: 111–122.

    Article  Google Scholar 

  • Pickavé, Martin. 2012. Human knowledge. In The Oxford handbook of Aquinas, ed. Brian Davies and Eleonore Stump, 311–325. Oxford: Oxford University Press.

    Google Scholar 

  • Pieper, Josef. 1953. On the ‘negative’ element in the philosophy of Thomas Aquinas. Trans. Fred Weick. CrossCurrents 4 (1): 46–56.

    Google Scholar 

  • Pini, Giorgio. 1999. Species, concept, and thing: Theories of signification in the second half of the thirteenth century. Medieval Philosophy and Theology 8: 21–52.

    Google Scholar 

  • ———. 2003. Scotus’s essentialism: A critique of Thomas Aquinas’s doctrine of essence in the ‘Questions on the metaphysics’. Documenti e studi sulla tradizione filosofica medievale 14: 227–262.

    Google Scholar 

  • ———. 2004. Absoluta consideratio naturae: Tommaso d’Aquino e la dottrina avicenniana dell’essenza. Documenti e studi sulla tradizione filosofica medievale 15: 387–438.

    Google Scholar 

  • Porro, Pasquale. 2016. Thomas Aquinas: A historical and philosophical profile. Trans. J.G. Trabbic and R.W. Nutt. Washington, DC: The Catholic University of America Press.

    Google Scholar 

  • Reynolds, Philip L. 2001. Properties, causality and epistemological optimism in Thomas Aquinas. Recherches de théologie et philosophie médiévales 68 (2): 270–309.

    Article  Google Scholar 

  • Cory, Scarpelli, and Therese. 2020. Aquinas’s intelligible species as formal constituents. Documenti e studi sulla tradizione filosofica medievale 31: 261–309.

    Google Scholar 

  • Spruit, Leen. 1994–1995. Species intelligibilis: From perception to knowledge. Vol. 2. Leiden/New York/Köln: Brill.

    Google Scholar 

  • Wippel, John F. 2000. The metaphysical thought of Thomas Aquinas: From finite being to uncreated being. Washington, DC: The Catholic University of America Press.

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. University of Parma, Parma, Italy

    Fabrizio Amerini

Authors
  1. Fabrizio Amerini
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Fabrizio Amerini .

Editor information

Editors and Affiliations

  1. Mount St. Mary#x2019;s University, Emmitsburg, MD, USA

    Joshua P. Hochschild

  2. University of San Diego, San Diego, CA, USA

    Turner C. Nevitt

  3. Wheaton College, Wheaton, IL, USA

    Adam Wood

  4. Eötvös Loránd University, Budapest, Hungary

    Gábor Borbély

Rights and permissions

Reprints and permissions

Copyright information

© 2023 The Author(s), under exclusive license to Springer Nature Switzerland AG

About this chapter

Check for updates. Verify currency and authenticity via CrossMark

Cite this chapter

Amerini, F. (2023). “The Essential Differentiae of Things are Unknown to Us”: Thomas Aquinas on the Limits of the Knowability of Natural Substances. In: Hochschild, J.P., Nevitt, T.C., Wood, A., Borbély, G. (eds) Metaphysics Through Semantics: The Philosophical Recovery of the Medieval Mind. International Archives of the History of Ideas Archives internationales d'histoire des idées, vol 242. Springer, Cham. https://doi.org/10.1007/978-3-031-15026-5_5

Download citation

Publish with us

Policies and ethics

Search

Navigation