https://orcid.org/0000-0002-7956-9085
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ABSTRACT
Empiricism is a claim about the contents of the mind: its classic slogan is nihil est in intellectu quod non fuerit in sensu, “there is nothing in the mind (intellect, understanding) which is not first in the senses.” As such, it is not a claim about the fundamental nature of the world as material. I focus here on in an instance of what one might term the materialist appropriation of empiricism. One major component in the transition from a purely epistemological claim about the mind and its contents to an ontological claim about the nature of the world is the new focus on brain–mind relations in the eighteenth century. Here I examine a Lockean trajectory as exemplified in Joseph Priestley’s 1777 Disquisitions Relating to Matter and Spirit. However, Locke explicitly ruled out that his inquiry into the logic of ideas amounted to a “physical consideration of the mind.” What does it mean, then, for Priestley to present himself as continuing a Lockean tradition, while presenting mental processes as tightly identified with “an organical structure such as that of the brain” (although he was not making a strict identity claim as we might understand it, post-Smart and Armstrong)? One issue here is that of Priestley’s source of “empirical data” regarding the correlation and indeed identification of mental and cerebral processes. David Hartley’s theory in his 1749 Observations on Man was, as is well known, republished in abridged form by Priestley, but he discards Hartley’s “vibratory neurophysiology” while retaining the associationist framework, although not because he disagreed with the former. Yet Hartley was, at the very least, strongly agnostic about metaphysical issues (and it is difficult to study these authors while bracketing off religious considerations). One could see Locke and Hartley as articulating programs for the study of the mind which were more or less naturalistic (more strongly so in Hartley’s case) while avoiding “materialism” per se; in contrast, Priestley bit the (materialist) bullet. In this paper I examine Priestley’s appropriation and reconstruction of this “micro-tradition,” while emphasizing its problems.
Acknowledgements
I thank Sebastiano Gino for his generous assistance with this paper, and John Barresi, Henry Schmidt, and Falk Wunderlich for comments on an earlier draft.
ORCID
Charles T. Wolfe http://orcid.org/0000-0002-7956-9085
Notes on contributor
Charles T. Wolfe is an Assistant Professor (ricercatore) in the Dipartimento di Filosofia e Bene Culturali, Università Ca'Foscari, Venice. He works primarily in history and philosophy of the early modern life sciences, with a particular interest in materialism and vitalism. Recent books: Materialism: A Historico-Philosophical Introduction (Springer, 2016) and La philosophie de la biologie: une histoire du vitalisme (Classiques Garnier, 2019); edited volumes include Monsters and Philosophy (2005), The Body as Object and Instrument of Knowledge (2010, with O. Gal), Vitalism and the scientific image in post-Enlightenment life-science (2013, with S. Normandin), Brain Theory (2014), and Philosophy of Biology before Biology (w. C. Bognon-Küss, 2019). He is co-editor of the book series ‘History, Philosophy and Theory of the Life Sciences’ (Springer). Papers available at [https://unive.academia.edu/CharlesWolfe]
Notes
1 Haakonssen, “The Idea of Early-modern Philosophy.”
2 Wolfe, “The ‘Physiology of the Understanding’ and the ‘Mechanics of the Soul’”; Wolfe, “Materialism and ‘the Soft Substance of the Brain’.”
3 Essay Concerning Human Understanding, I.i.2
4 Hartley’s Theory of the Human Mind, 1775, xx
5 Wolfe, “Materialism”; Wunderlich, “Varieties of Early Modern Materialism.”
6 Toland, Letters to Serena, IV, § 7, 139; Collins, A Reply to Mr. Samuel Clarke’s Defense of his Letter to Mr. Dodwell (1707), in Clarke, Works, III, 807; Priestley, Hartley’s Theory of the Human Mind, xx.
7 Wolfe and van Esveld, “The Material Soul.”
8 Hatfield, “Psychology as a Natural Science,” 390. He adds that, “In point of fact, of all the major eighteenth century authors who made contributions to the development of psychology, only Erasmus Darwin allowed that mind might be material; nineteenth century founders of psychology, including Wundt, Helmholtz, Lotze, Ebbinghaus, James, Munsterberg, and Binet, banished the very question from scientific psychology” (Hatfield, “Psychology as a Natural Science,” 390).
9 Jolley, Locke. His Philosophical Thought; Jolley, Locke’s Touchy Subjects. I agree with Jolley (especially in the earlier, more cautious work) that Locke was, at the very least, agnostic as to the possibility of thinking matter and, moreover, that, by even formulating it as a possibility, he was explicitly making a move on the board on which idealism and materialism were in conflict, so to speak. As I seek to show here, this does not mean we should disregard Locke’s desire to not be taken to be putting forth a science of the mind. A study of the “understanding” was something different (as Serjeantson also notes, with a different emphasis from mine: Serjeantson, “‘Human Understanding’ and the Genre of Locke’s Essay”).
10 “I shall not at present meddle with the physical consideration of the mind; or trouble myself to examine wherein its essence consists; or by what motions of our spirits or alterations of our bodies we come to have any sensation by our organs, or any ideas in our understandings; and whether those ideas do in their formation, any or all of them, depend on matter or not” (Locke, Essay, I.i.2). Although, Locke breaks his own vows when discussing the association of ideas and explicitly explains such mental processes in terms of animal spirits, that is, materially (Locke, Essay, II.xxxiii.6).
11 Rey, “Diderot and the Medicine of the Mind”; Wolfe, “The ‘Physiology of the Understanding’ and the ‘Mechanics of the Soul’.”
12 Interestingly, Marx already emphasized the trajectory from Locke to Hartley and Priestley in Die Heilige Familie, drawing on Renouvier, as was noted by Olivier Bloch, “Marx, Renouvier et l’histoire du matérialisme,” and more recently reiterated in A. Thomson, Bodies of Thought, vii.
13 Priestley, An Examination, Introduction, 4. To be clear (one anonymous reader found the issue confusing), Priestley doesn’t use the term “neurophilosophy” to describe Locke, but I suggest that that is precisely how he reconstructs Locke. As far as I know, the term “neurophilosophy” came into usage with Patricia and Paul Churchland in the 1980s.
14 Harris, Liberty and Necessity, 16.
15 Hartley, Observations on Man, I, 13–16. Hartley cautiously tries to ward off ideological difficulties, adding that “I do not, by ascribing the performance of sensation to vibrations excited in the medullary substance, in the least presume to assert, or intimate, that Matter can be endowed with the power of sensation” (ibid, I, 33). That brain–mind relations and indeed the “identity” between cerebral and mental processes can be fully described mechanistically, “with the same certainty as other effects [ … ] from their mechanical causes” (ibid, I, 500) is nevertheless not, for Hartley, tantamount to an ontological commitment to a materialist “substance metaphysics.”
16 Garrett, “Mind and Matter,” 191. Further, I should clarify that Priestley’s cerebral materialism does not mean that he rejects ontological materialism (as F. Wunderlich notes).
17 Priestley, An Examination, Introduction, 7.
18 Hartley, Observations on Man, I, 16. For discussion, see Thébert, “David Hartley.”
19 He also notes that empirical advances have made the vibratory model seem out of date, but he does not reject it out of hand (Priestley, Hartley’s Theory, xviii). Priestley’s edition ends with a table of the omitted sections. The only changes he made in what he retained were those necessary for a sense of continuity in the argument. It should be noted that Priestley amassed several volumes of ‘facts concerning human nature’ intended for a volume illustrating Hartley’s theory, but these were destroyed in the Birmingham Riots of 1791 (letter to Theophilus Lindsey, in The Theological and Miscellaneous Works of Joseph Priestley, I, pt. I, 5–6; Webb, “Perspectives on David Hartley,” 29).
20 Priestley, An Examination of Dr. Reid’s Inquiry into the Human Mind on the Principles of Common Sense, Introduction, 2.
21 Priestley, Hartley’s Theory of the Human Mind, xiii. All quotes from Hartley’s Theory are from the first of the three introductory essays, thus they are from Priestley, not Hartley.
22 ibid., xv.
23 Priestley, Hartley’s Theory of the Human Mind, vii.
24 Priestley, Disquisitions, 79, Priestley’s emphasis.
25 Priestley, Disquisitions, 79; Priestley, Hartley’s Theory of the Human Mind, xix.
26 Priestley, Disquistions, 28, his emphasis.
27 ibid.
28 Hartley, Observations on Man, I, 511.
29 Respectively, Priestley, Disquistions, 91, and Priestley, Hartley’s Theory of the Human Mind, 108 (on memory).
30 Priestley, Hartley’s Theory of the Human Mind, xviii. Garrett comments that “Hydrostatics may have been too crude to make materialism compelling, but by midcentury the evidentiary base for materialism had become more viable, as Hartley had shown” (Garrett, “Mind and Matter,” 188).
31 Boscovich, Philosophiae naturalis/Natural Philosophy, 16. On the influence of such ideas on Priestley’s materialism, see Yolton, Thinking Matter, ch. 6, esp. 110f.; Schofield, The Enlightened Joseph Priestley, 70. The extent of Boscovich’s influence on Priestley has been contested (Brock, “Priestley, Enlightened Experimentalist”; cf. Dybikowski, “Priestley, Metaphysician and Philosopher of Religion”); I am not making any strong biographical claim beyond the presence of specifically chemical and “Boscovich-influenced” ideas in the matter theory of the Disquisitions. Now, I take note of Priestley’s claim that his materialism was scientifically nourished, but it is possible to take this claim with a grain of salt, if one considers that his arguments are conceptual in nature and (as S. Gino suggests) that the appeals to electricity are primarily analogical. However, my overall emphasis is on the intersection and mutual “contamination” between philosophical materialism and projects for a science of mind, which implies that I am not strictly distinguishing between some “pure” philosophical discourse and some “empirical” scientific discourse.
32 Priestley, Disquisitions, xxxviii; cf. also Priestley, Disquisitions, section II, 11. (Priestley also states that it is because anti-materialists think of matter as passive and inert that they think it is dangerous to attribute intelligence or a mind to it; if matter is recognized as it really is, as active, this objection is dispelled. Thus he can even speak of the “immateriality of matter”: Priestley, The History and Present State of Discoveries Relating to Vision, Light, and Colours, 392; thanks to Udo Thiel for this reference.) The first synthesis of these ideas on attraction and repulsion (for which not just Boscovich but also Stephen Hales was a source) was Priestley’s History of Optics (1772), and they are a major theme in Priestley, Free Discussion of the Doctrines of Materialism (the exchange with Price). See also Priestley, History and Present State of Electricity.
33 Priestley, Experiments and Observations on Different Kinds of Air, 277–8. It bears noting that this is listed among other “queries,” though Priestley arguably believed that the explanation was correct.
34 See the discussion of Priestley in Gino, Medicina e filosofia nell’Illuminismo scozzese. I’m grateful to S. Gino for sharing his work on the topic with me.
35 Priestley, Disquisitions, 109. He also considers that this “newer” materialism was already espoused by the Church Fathers. “Gross matter” seems to mean the matter of an arch-mechanist à la Hobbes, inert and passive, whereas more complex concepts of matter involve activity, force, self-organization. In 1775, in his introduction to his (abridged) republication of Hartley’s Observations, Priestley describes the “gross and most general” vision of matter as “subject to no laws but those of the five mechanical powers,” and he calls this “a turn of thinking that prevailed very much about half a century ago” (Priestley, Hartley’s Theory, xviii).
36 Cranefield, “On the Origin of the Phrase nihil est in intellectu.”
37 On the different “negotiations” of conceptual and scientific space between empiricism (as a doctrine about the sources of knowledge via the senses) and the duo of neurophilosophy and materialism2 (i.e. cerebrally based ontologies of mental life meant either as direct contributions to science or as conceptual facilitations thereof), including in Bonnet, see Wolfe, “The Physiology of the Understanding”; Dupont, Wolfe, and Cherici (eds.) Empirisme et fonctions cérébrales.
38 Priestley, An Examination of Dr. Reid's Inquiry…, lvi-lvii. Antoine Maubec, in Chapter IV of his 1709 work on mental faculties and the brain, the Principes phisiques de la raison, et des passions des hommes, explicitly connects both of these empiricist motifs: he will not assert “anything that is not confirmed by experience or self-evident,” and by following this method, he will show that “all of our knowledge comes from sense-impressions.” Maubec extends this issue in later chapters (V-VI), describing how in the course of development, sense-impressions imprint themselves on the child's brain as if on a piece of wax.
39 Priestley, Disquisitions Relating to Matter and Spirit, 91. Priestley also argues that, if we consider the principle of thinking as something internal to (but separate from) the brain, this results in a regress, as nothing prevents us from assuming a second principle of thought which resides in the first one, and so on (Priestley, A Free Discussion of the Doctrines of Materialism, 51). He is not always so strict regarding the language of “correspondence,” however.
40 McLaughlin, “Vitalism and Emergence.”
41 Priestley, A History of Early Opinions concerning Jesus Christ, vol. 1, 84–5.
42 Tapper, “The Beginnings of Priestley’s Materialism,” 77; Garrett, “In Defense of Elephants.”
43 Priestley, An Examination of Reid, Appendix, II, “Of Mr. Harris’s Hypothesis Concerning Mind and Ideas,” 339.
44 Priestley does not refer in this context to La Mettrie, who argues in just this way about the soul (e.g. in L’Homme-Machine, in La Mettrie, Œuvres philosophiques, vol. 1, 98), but he was a great admirer of d’Holbach (Priestley, Works, IV, 389). He quotes La Mettrie’s L’Homme-Machine somewhat oddly as supporting (out of agnosticism) the possibility of immortality, or at least some form of life after death (Priestley, Disquisitions relating to Matter and Spirit, 163); thanks to Pascal Taranto for pointing this out to me.
45 See the analyses of Garrett, Demeter, and Gino.
46 Priestley, Disquisitions, 89
47 Priestley, Disquisitions relating to Matter and Spirit, 86–7.
48 see Collins in Clarke, Works, vol. 3, 859 ff. Priestley’s emergentism is crucial in his response to Richard Price in Priestley and Price, A Free Discussion of the Doctrines of Materialism and Philosophical Necessity (e.g. Priestley, Works, IV, 42). Cf. also Martin and Barresi, The Naturalization of the Soul, 132–8.
49 Diderot’s “neurophilosophical” reflections on brain, memory, will, and the like are to be found in his unpublished, and perhaps unfinished (it is a matter of specialized scholarly debate), Éléments de physiologie, which he worked on in the 1770s for a number of years. On Diderot’s neurophilosophy, see Wolfe, “Materialism and ‘the Soft Substance of the Brain’”; on the relation between this work of Diderot’s and his materialism overall, see Bourdin, “Du Rêve de d’Alembert aux Éléments de physiologie.”
50 Priestley, Letters to a Philosophical Unbeliever, 26.
51 Priestley, An Examination, 32.
52 Priestley, A Free Discussion of the Doctrines of Materialism, 256–7.
53 Priestley, Hartley’s Theory of the Human Mind, xx. This was ridiculed by Reid as “Let us suppose with Dr. Priestly that all the Mental Powers of Julius Cæsar resulted from the Organical Structure of his Brain” (Wood, Thomas Reid on the Animate Creation, 134).
54 Thomson, Bodies of Thought; Wunderlich, “Priestley on Materialism and the Essence of God.”
55 ibid.
56 Priestley, An Examination of Dr. Reid’s Inquiry, 36.
57 Reid to Richard Price, 10 April 1775, quoted by Garrett, “In Defense of Elephants,” 138.
58 This distinction, while helpful in a variety of contexts, does not map on to early modern texts very well; it should be used with caution. I found Garrett’s suggestions (Garrett, “In Defense of Elephants,” esp. 141) very helpful here.
59 John P. Wright does note, however, the influence on Locke of Thomas Willis’ lectures on the soul at Oxford, and observes that Willis uses the language of fitly disposed systems of matter (Wright, “Locke, Willis, and the Seventeenth-century Epicurean Soul,” 254). However, Wright then notes, consonant with the present essay, that one should not confuse Willis’ more “Epicurean” project to naturalize the soul with Locke’s rejection of “physical considerations of the mind” (cf. Wolfe and van Esveld, “The Material Soul,” 255–6).
60 Schneewind, “The Active Powers.” Historians of psychology tend to consider that pneumatology in the eighteenth century was more prominently taught with a commitment to the immateriality of the soul in the background (Thomas Reid being a leading figure here by the end of the century, in the Scottish context), but it was also taught e.g. in Unitarian institutions as a materialist science, or, better put, a science with materialist commitments (here, Priestley is a major figure), as John Barresi has observed (personal discussion). Indeed, both trends can be considered Lockean, not least considering Locke’s bracketing-off of a natural science of the mind. Further, Reid had his own neuropsychological concerns, which would make for a different story (see Wood, Thomas Reid on the Animate Creation; Demeter, “Philosophical Methods”; Gino, “Medicina e filosofia nell’Illuminismo scozzese”).
61 Wright, “Locke, Willis, and the Seventeenth-century Epicurean Soul”; Sutton, “Carelessness and Inattention.”
62 Yolton, Thinking Matter, 124.
63 With the exception of associationist psychology in thinkers such as Mill and Bain. Indeed, as Barresi has noted, there was an “aftermath” of Priestley’s project in Thomas Cooper’s work on materialism and association psychology, and in Thomas Belsham’s “philosophy of mind,” based on his pneumatology course at the Unitarian school of Hackney, and Erasmus Darwin, who was followed by William Lawrence. However, according to Reed’s From Soul to Mind, this materialist associationist line ended there, with a “victory” for Reid’s or Hume’s psychology.
64 Mensching, “Le matérialisme,” 525, 513.