Descartes on the distinction between primary and secondary qualities

ABSTRACT

Descartes did not use the terms ‘primary’ and ‘secondary’ qualities, but a similar distinction emerges from his texts: certain qualities of objects (such as size and shape) are intrinsic properties of matter, whereas others (like colours and smells) are products of the interaction with a perceiver. A common interpretation states that the division between primary and secondary qualities is explained by the way in which we are acquainted with them: an idea of a primary quality is similar to its physical causes, and it is clearly and distinctly perceived by the intellect. An idea of a secondary quality is dissimilar to its physical causes and it is obscurely and confusedly perceived by the senses. This view receives the name of ‘bifurcation reading’ (Simmons, A. ‘Descartes on the Cognitive Structure of Sensory Experience’. Philosophy and Phenomenological Research, LXVII, no. 3 (November 2003)). While it integrates well some textual occurrences, it creates a problematic fragmentation within single acts of perception. This paper contends that this reading is incorrect. It presents several arguments for the claim that the distinction of qualities is due to the different ways in which our ideas of them misrepresent their physical causes. Then, Descartes’ dissimilarity thesis between physical objects and our ideas of them remains a structural feature of his theory of sensory perception and not a local phenomenon affecting only ideas of secondary qualities.

KEYWORDS:

• Descartes
• primary and secondary qualities
• bifurcation reading
• sensory perception

ORCID

Anna Ortín Nadal http://orcid.org/0000-0003-1668-8527

Notes

1 Descartes’ works are cited in the Adam and Tannery edition (abbreviated AT with volume and page numbers) and the translation by Cottingham, Stoothoff, and Murdoch (abbreviated CSM with volume and page numbers). The translation of The World is by S. Gaukroger (abbreviated G with page number).

2 Before Descartes, Galileo had offered a similar argument in The Assayer (1623). Although his corpuscularianism was far from being a purely kinetic theory, he can be considered a forerunner of the distinction between primary and secondary qualities: ‘whenever I conceive of any material substance, I immediately feel the need to think of it as bounded, and as having this or that shape, being large or small (…) But that it must be white or red, bitter or sweet (…) my mind does not feel compelled to bring in as necessary accompaniments’ (Discoveries and Opinions of Galileo, 274).

3 Admittedly, Scholastic theories of perception were more diverse and detailed than Descartes acknowledged. Whereas it is true that Scholastic thinkers were rarely tempted by anti-realism about secondary qualities, this should not be equated to a homogeneous endorsement of the thesis that these exist in objects as we experience them. For a treatment of Scholastic realism, see Pasnau (Metaphysical Themes 1274-1671, 492–4). I thank an anonymous reviewer for drawing my attention to this reference.

4 That Descartes was set to clarify this systematic ambiguity in the use of the terms for secondary qualities has been pointed out by Pasnau (Metaphysical Themes 1274-1671), who draws attention the fact that an eminent Cartesian like Malebranche merited Descartes with having clarified the discussion precisely in that respect: ‘Only since Descartes do we respond to these confused and indeterminate questions – whether fire is hot, grass green, sugar sweet, and so on – by distinguishing the equivocation of the sensible terms that express them’ (Search After Truth VI.2.2)

5 Even if not explicitly endorsed, the BR is often taken for granted in assessments of Descartes’ theory of perception. According to Maull (‘Cartesian Optics and the Geometrisation of Nature’, 262), Descartes’ view is that the mind directs its awareness separately to primary and secondary qualities, and that the intellect plays no part in the reckoning of secondary qualities. Wilson (Ideas and Mechanism, 36) reads the Optics and the Sixth Replies as presenting a theory in which the perception of primary qualities involves the intellect, as opposed to the perception of secondary qualities. Elements of this interpretation can be found in Buroker (‘Descartes on Sensible Qualities’, 589), Atherton (Berkeley’s Revolution in Vision, 30), and Jolley (The Light of the Soul, 92), who equates the theories of Descartes and Malebranche in this respect.

6 For the line of thought that I will present in this section, I am indebted to Simmons’ compelling case against the BR (‘Descartes on the Cognitive Structure of Sensory Experience’). Her position is my starting point, although I eventually differ from it in the argumentation. Her rejection of the BR aims at the claim that Descartes’ account of the cognitive structure of sensory perception is shaped by the collaborative activity of the senses and the intellect for ideas of both primary and secondary qualities.

7 A more or less implicit commitment to the BR coexists in the literature with the acknowledgement that the dissimilarity thesis is, beyond doubt, a feature of Descartes’ philosophy. This incompatibility is not frequently explored. In his account of Descartes on colour, Cottingham (‘Descartes on Colour’, 232) reads Descartes’ anti-empiricist remarks concerning the senses as referring only to secondary qualities. In her discussion of Descartes’ ontology of sensation, Atherton (‘Green Is Like Bread’, 33) similarly omits the claim that the dissimilarity thesis applies to both types of qualities. A criterion for the distinction of qualities in terms of similarity/dissimilarity with their physical causes is supposed by Schmaltz (‘Descartes on Innate Ideas, Sensation and Scholasticism’). Elements of this assumption are also present in Beyssade (Études sur Descartes, 156).

8 Pasnau is concerned with the evolution of the distinction between primary and secondary qualities in the Early Modern period in general. Here I borrow his terminology for the case of Descartes.

9 The distinction between designations is meant to elucidate the way in which Descartes deals with systematic ambiguity in the way in which we talk about secondary qualities. The designations track the ways in which, by using a single term, we can characterize either a mode of body or a mode of mind. This should not be read as suggesting that Descartes is qualifying a single entity in two ways, but rather enabling us to characterize two substantially different modes with the same term.

10 Nolan (Primary and Secondary Qualities) and Wilson (Ideas and Mechanism) have mischaracterized Descartes’ position to some extent precisely because of this, although their verdicts differ. While Nolan defends a nominalist reading of Descartes on secondary qualities, Wilson identifies conflicting views within the texts. On my reading, there is more than a nominalist stance in Descartes’ view on secondary qualities, and the seeming conflict can be explained away by distinguishing the use of the two designations.

11 My analysis also improves on Simmons’ argument insofar as it acknowledges and resolves a problematic textual fact – namely, Descartes’ insistence on characterizing only examples of primary qualities as intellectual, clear, and distinct (Section 2.2).