Early modern philosophy is one of several areas of interest for the below postdoc opportunity.

The Irish Research Council (IRC) annually offers postdoctoral fellowships of one or two years’ duration. Applicants of any nationality are eligible, but must be in residence at an Irish university during the fellowship period. Application is made under the mentorship of a member of the academic staff at the university where the applicant hopes to reside.

The Department of Philosophy at Trinity College Dublin welcomes applications under this scheme. Mentors are available, in particular, in the following areas:

  • Epistemology (Paul O’Grady)
  • Philosophy of Language (James Levine)
  • Philosophy of Religion (Paul O’Grady, Kenneth Pearce)
  • Ethics (Ben Bramble)
  • Phenomenology (Lilian Alweiss)
  • History of Philosophy:
    • Ancient (Vasilis Politis)
    • Medieval (Paul O’Grady)
    • Early Modern (Kenneth Pearce)
    • Modern European (Lilian Alweiss)
    • Analytic (James Levine, Paul O’Grady)

There has been a rich tradition of philosophical excellence at Trinity since its foundation in 1592 and today the Department is a close-knit, lively intellectual community of researchers, teachers and students that combines high-quality teaching with expansive research activity.

The deadline for applications is 30 November, 2017. Prospective applicants may either contact their proposed mentor directly or contact the Philosophy Department’s Director of Research, Kenneth Pearce (pearcek@tcd.ie).

Complete details on the Government of Ireland Postdoctoral Fellowship scheme can be found at: http://research.ie/funding/goipd/?f=postdoctoral.

More information on the TCD Philosophy Department can be found at: http://www.tcd.ie/Philosophy/.


I am currently re-reading Margaret Cavendish’s Observations upon Experimental Philosophy, as I will be teaching it in the near future. There are two features of the text that have struck me this time through, to which I was perhaps less attuned on my last read:

  1. I am struck by the extent to which Cavendish’s reasons for panpsychism match the reasons given in more recent discussions (e.g., Nagel, Chalmers). The basic line of argument seems to be: human beings are made of ordinary matter, just like everything else. But human beings have sensitive/rational capacities that can’t be explained mechanically. So there must be something non-mechanical—specifically, something sensitive/rational—in (all) ordinary matter. Further, she goes on to suggest, this hypothesis can explain how not just lower animals but even inanimate objects act in an orderly, seemingly intelligent fashion.
  2. I am struck by the extent to which Cavendish’s skepticism about the use of scientific instruments (e.g., microscopes) is based on a criticism of her contemporaries (e.g., Hook) for their failure to appreciate that the scientist and his instruments are themselves part of nature.

These two observations together paint a picture of Cavendish as a naturalist in the very same sense that Della Rocca applies that term to Spinoza: that is, despite her occasional talk of the supernatural/spiritual soul and God, she rejects any attempt to ‘bifurcate’ the world or to see the human being as somehow standing apart from or outside nature.

(Cross-posted at blog.kennypearce.net.)

Earlier this year, Christia Mercer published a fascinating article on the influence of Teresa of Avila on Descartes. Mercer shows (in my view convincingly) that the structure of Descartes’s Meditations is patterned after Teresa’s The Interior Castle, an extremely popular text at the time, especially in Jesuit circles such as the college where Descartes was educated. This line of influence has been missed by scholars because philosophers are dismissive of women and of religious mystics, and Teresa was both. (I hasten to add: scholars are often quick to forget that certain male philosophers such as Plotinus and Augustine were undeniably also mystics.) Mercer has now written  an essay on The Stone (the New York Times philosophy blog) presenting some of the same material for broader audiences.

A thread present in the journal article, but receiving greater emphasis in The Stone, is the extent to which this finding about Descartes and Teresa (and other related findings) calls for the rejection of a certain traditional narrative about the history of early modern philosophy. Again, I agree. However, I want to comment here on Mercer’s discussion of the origination of the traditional narrative. I am genuinely uncertain whether I am disagreeing with her or merely adding some additional nuance and detail to the account. Mercer claims in The Stone that “The longstanding story about Descartes’s creation of a ‘new philosophy’ that broke radically with medieval ‘ways of thinking’ and that marked ‘the dawn of modern times’ was promoted by philosophers who came after Kant.” The earliest specific time period she specifies for the ‘promotion’ of this story is the 1820s.

This strongly suggests to the reader that this story originated after Kant (but note that Mercer’s actual claim is only that it was ‘promoted’ by certain post-Kantian thinkers). Here I want to argue that a precursor of this narrative already existed by the late 17th century (though with certain important differences), and explore some of the implications of this fact for the historiography of philosophy.

The first point that needs to be recognized if we are to understand the emergence of the narrative in question is that in the 17th and 18th centuries, ‘modern’ or ‘new’ philosophy is the name of a controversial school of thought. When we use the term ‘early modern philosophy’ to refer to all philosophy that takes place during this period, we obscure the fact that there were self-consciously anti-modern philosophers active in the 17th and 18th centuries, and these people were doing serious philosophical work. For instance, John Sergeant (1623-1707) defended a version of the Aristotelian species theory of perception and Peter Browne (d. 1735) defended the view that testimony (which he called ‘authority’) is an independent and fundamental source of epistemic justification. One cannot deny that these people were philosophers. Yet they explicitly criticize ‘modern’ philosophy. Further, as late as 1733 Browne is defending philosophical positions with patristic citations. (Peter Browne, don’t you know it’s 1733 and not 1233?!) But Browne also has serious philosophical arguments, just as Thomas Aquinas, despite his reliance on authority, offers serious philosophical arguments. One cannot deny that Sergeant and Browne are philosophers, but it is misleading to describe them as ‘modern’ philosophers.

So what is ‘modern’ (or ‘new’) philosophy? I was prompted to investigate this question a little while back by an invitation from Kirsten Walsh to participate in a HOPOS panel on alternative narratives of early modern philosophy. My interests are primarily in the late 17th and early 18th centuries. (I am the Berkeley guy, after all), so I decided to investigate the question of how ‘modern’/’new’ ‘philosophy’/’science’ was understood in this period. I did this by searching Early English Books Online and Eighteenth Century Collections Online for works containing these terms in the title or subtitle, and looking at how this school of thought was described and which philosophers were taken as its key advocates. (Note that my search was limited to English language sources.) I have no idea when (or if) I might get around to writing this up as a proper journal paper (so many papers to write, so little time to write them in!), so I thought this would be a good opportunity to present a little summary of the most interesting works I found, and the conclusions I drew from them.

  • Simon Patrick, A Brief Account of the New Sect of Latitude-Men: Together with Some Reflections upon the New Philosophy (1662). This was the true gem of the bunch, and one of the earliest explicit historical reflections on New Philosophy (and also latitudinarian Anglicanism). Also, it contains the amazing Tale of the Aristotelian Clock-mender. Patrick’s overall narrative is the story of an early 17th century Scientific Revolution that overturned the old Aristotelian worldview and set philosophy on a new (and superior) mechanistic footing. The Aristotelian worldview was overthrown, according to Patrick, by a variety of “notable new phenomena recently discovered,” including, for instance, “the ansulae [Latin: little handles] of Saturn and four Moons about Jupiter [which] were never heard of till Galileo’s Nuncius Sidereus [Starry Messenge (1610)] brought the news” (p. 20). Galileo is the chief hero of Patrick’s story, but he gives honorable mention to Descartes, Scheiner, Tycho, Gilbert, and Boyle. According to Patrick, these philosophers rejected the authority of Aristotle and instead pursued empirical research and developed a mechanical picture of nature. (Seriously, this little pamphlet is awesome. If you have EEBO access, go read it.)
  • W. Simpson, Philosophical Dialogues Concerning the Principles of NATURAL BODIES: WHEREIN The Principles of the Old and New Philosophy are stated, and the New demonstrated, more agreeable to Reason, from Mechanical Experiments and its usefulness to the benefit of mankind (1677). (How’s that for a subtitle?!) Simpson also takes (anti-Aristotelian) mechanism as the central principle of the new philosophy, and treats Bacon and Boyle as its key exponents. (Descartes is not mentioned.)
  • Anne Conway, The Principles of the most Ancient and Modern Philosophy: CONCERNING God, Christ, and Creatures, viz. of Spirit and Matter in general whereby may be resolved all those Problems and Difficulties, which neither the Schools nor Common Modern Philosophy, nor by CartesianHobbesian, or Spinosian could be discussed (1690). Conway never defines ‘modern’ philosophy, and she’s not very explicit about exactly what its common features are, but note that there are three categories here of philosophy current in her own time: Scholastic philosophy (still an active enterprise!), ‘Common Modern Philosophy’, and the particular systems of great modern philosophers. The great modern philosophers are Descartes, Hobbes, and Spinoza.
  • William Wotton, Reflections upon Ancient and Modern Learning (1697). This one doesn’t actually use ‘philosophy’ or ‘science’ in the title, but I included it anyway, and it turned out to provide the most detailed account of modern philosophy of the sources I consulted. Note that Wotton does use the word ‘modern’ rather than ‘new’. His account is worth quoting at length:

    As for Modern Methods of Philosophizing, when compared with the Ancient, I shall only observe these following Particulars. (1.) No Arguments are received as cogent, no Principles are allowed as current, amongst the celebrated Philosophers of the present Age, but what are in themselves intelligible; that so a Man may frame an Idea of them, of one sort or other. Matter and Motion, with their several Qualities, are only considered in Modern Solutions of Physical Problems. Substantial Forms, Occult Qualities, (x) [I don’t know what the x is for! -KP], Intentional Species, Idiosyncrasies, Sympathies and Antipathies of Things, are exploded; not because they are Terms used by Ancient Philosophers, but because they are empty Sounds, Words whereof no Man can form a certain and determinate Idea. (2.) Forming of Sects and Parties in Philosophy, that shall take their Denominations from, and think themselves obliged to stand by the Opinions of any particular Philosophers, is, in a manner, wholly laid aside. Des Cartes is not more believed upon his own Word, than Aristotle: Matter of Fact is the only thing appealed to … (3.) Mathematics are joined along with Physiology, not only as Helps to Men’s Understandings, and Quickeners of their Parts, but as absolutely necessary to the comprehending of the Oeconomy of Nature, in all her Works. (4.) The New Philosophers [NB: ‘new philosophers’ are those who follow ‘modern methods of philosophizing’. -KP], as they are commonly called, avoid making general Conclusions, till they have collected a great Number of Experiments, or Observations upon the Thing in hand … So that Inferences that are now a-days made from any Enquiries into Natural Things, though perhaps they be set down in general Terms, yet are (as it were by Consent) received with this tacit Reserve, As far as the experiments or Observations already made, will warrant (pp. 364-365).

    Yes, the enumeration is original. (Wotton could have been an analytic philosopher!) Note also that, curiously enough, Descartes is here the poster-child for ‘modern’ system-builders, yet the method of modern philosophy is Baconian empiricism! In any event, Descartes is treated as a figure of crucial importance in the development of new methods of philosophizing that have overturned the old Aristotelian system in favor of a mechanistic world picture.

What can we conclude from this? Early 17th century philosophers, such as Galileo, Bacon, Descartes, Hobbes, and Gassendi, self-consciously portrayed themselves as overthrowing old Aristotelian systems by the rejection of ancient authorities in favor of new philosophical methods. Because this relies on a rejection of authority it is to a large extent individualistic. (It makes sense, in fact, that Descartes, in trying to push this individualistic approach to epistemology as against reliance on authority, would find a series of solitary meditations, patterned on Teresa’s, an appropriate mode of presentation.) Of course, in doing this these philosophers were influenced by their predecessors just as everyone is. But their opposition to reliance on authority led them to minimize this influence. By the end of the century, a significant number of thinkers (at least in England) had bought this story hook, line, and sinker. They believed that this group of mechanistic anti-authoritarian thinkers had produced an intellectual (scientific, philosophical) revolution by demolishing Medieval ways of thinking. Note also that ‘modern’ thinkers from this period typically treat ‘the Schools’ or ‘the School-men’ not just derisively but also monolithically. That is, we’re already developing the notion that there was such a thing as the Medieval way of thinking.

Now, as I said, I’m not sure I’m really disagreeing with Mercer here. In fact, the story I’ve just told could be read as a prequel to her story of the development of the standard narrative. This is because the narrative that exists in my late 17th century sources is missing some crucial elements of the standard narrative that develops in the 19th century. Here are some key differences:

  1. In the late 17th century, Descartes is one of the founders of the ‘new philosophy’; in the standard narrative he is the (one and only) founder. By the early 20th century, Galileo, Bacon, and Boyle belong to the history of science which is separate from the history of philosophy. Hobbes, Gassendi, and friends drop out of the picture entirely. (The extent to which Hobbes and Gassendi vanish can be recognized by the frequency with which Locke is treated as the founder of the modern empiricists.)
  2. In the late 17th century, the early 17th century debate is portrayed as the moderns vs. the School-men or the adherents of the ancients. As mentioned, Wotton even associates Descartes with Baconian methodology. In the standard narrative, however, the rationalist/empiricist dispute is the main event and anyone who put Descartes and Bacon on the same side would be regarded as incompetent.
  3. In the late 17th century, mechanism and epistemological individualism are the key principles of ‘new’ or ‘modern’ philosophy. Theories of ideas are made necessary because mechanism undermines Scholastic/Aristotelian theories of perception; rationalist and empiricist theories in epistemology (insofar as there are such things) are seen as answers to the question: “if we shouldn’t just rely on the authority of the ancients (or the Church) then how should we form beliefs?” These issues are, in other words, derivative of more fundamental issues.

So what happens in the historiography of modern philosophy between where my story leaves off around 1700 and where Mercer’s story picks up around 1820? And how is the history being portrayed by non-English-speaking philosophers and historians in this period? I’m afraid those are questions that will have to be left for another day, and perhaps another scholar.

(Cross-posted at blog.kennypearce.net)

Call for Papers

Spinoza on Virtue and Vice

The North American Spinoza Society will be sponsoring a session at the 2018 meeting of the Central APA on the topic “Spinoza on Virtue and Vice.” Papers on any aspect of Spinoza’s views on virtues and (or) vices are welcome. The 2018 Central APA meeting will be held in Chicago from February 21 to February 24.

To participate, please submit an abstract. An abstract should be prepared for blind review and no more than 750 words. Include contact information and the title of the paper in the email with the abstract attached as a word, pdf, or rtf document. With the subject heading NASS Central 2018, please send submissions to: adyoupa@gmail.com .

Deadline for submission: September 1, 2017.

HOPOS: The Journal of the International Society for the History of Philosophy of Science seeks proposals for special issues of the publication. More information about the call for proposals, including details on the submission process, can be found at


If you plan to submit a proposal for a special issue, please write to hoposjournal@gmail.com with an expression of interest, or with questions, by September 1, 2017.

The deadline for final proposals is November 30, 2017.

Before you submit your final proposal, you are encouraged to review HOPOS contributions relevant to your proposed subject area. To browse articles and issues, including a free online sample issue, visit


If you are a member of the International Society for the History of Philosophy of Science, you have free access to HOPOS; write to hoposjournal@gmail.com for login instructions.

In the first two editions of the Principia, Newton makes two pronouncements about the scope of natural philosophy that appear to be in tension with one another. In the first (1687) edition Preface to the Reader, Newton writes, “the basic problem of [natural] philosophy seems to be to discover the forces of nature from the phenomena of motions and then to demonstrate the other phenomena from these forces” (Janiak 60). In the famous General Scholium added to the second (1713) edition, Newton writes, “to treat of God from the phenomena is certainly a part of natural philosophy” (Janiak 113). We know from Newton’s correspondence that this was a late addition to the text (Janiak 158).

These two pronouncements are not inconsistent, for the first claims that a certain class of questions constitutes “the basic problem of [natural] philosophy,” while the second claims that a different, apparently disconnected, class of questions is “a part of natural philosophy.” Nevertheless, there seems to me to be a tension, for if natural philosophy is a unified enterprise then one would expect all of the questions it asks and answers to be tightly connected with its “basic problem” and unless one thinks (as perhaps Descartes does?) that force is divine action or something, then it is unclear that this further question is tightly connected in this way. Perhaps Newton thinks that a legitimate but peripheral question for natural philosophy is why God has created the specific forces that exist, rather than other forces, or perhaps he simply doesn’t think of natural philosophy as a tightly unified enterprise organized around “the basic problem”. This is not spelled out in the General Scholium, and indeed the paragraphs on God have the appearance of an irrelevant digression.

What I want to suggest is that Berkeley’s De Motu (1721) can be seen in part as a defense of rigorous adherence to Newton’s position in the first edition preface (reinterpreted in light of Berkeley’s own account of force) as against Newton’s remark in the General Scholium.

In the Principles (1710), Berkeley refers to natural philosophers as “Those men who frame general rules from the phenomena, and afterwards derive the phenomena from those rules” (§108). This appears to be an echo of Newton’s first edition Preface. Curiously, though, Berkeley omits all mention of force, which is the central concept in Newton’s physics. More generally, in the Principles, Berkeley shows very little concern about the nature or status of force, and it is unclear whether he even really recognizes its importance to Newton. This oversight is rectified in De Motu.*

In De Motu Berkeley writes:

in mechanics, notions are initially established—that is, definitions and first general statements about motion—from which more remote and less general conclusions are subsequently deduced by a mathematical method. And just as the magnitudes of particular bodies are measured by applying geometrical theorems, so likewise the motions of any parts of the system of the world, and the phenomena that depend on them, become known and determined by applying the universal theorems of mechanics. That is all that a physicist should aim to realize.

Just as geometers, for the sake of their discipline, invent many things which they themselves cannot describe nor find in the nature of things, for exactly similar reasons a student of mechanics employs certain abstract and general terms and feigns in bodies a force, an action, an attraction or solicitation, etc. which are extremely useful in theories and propositions, as also in calculations of motion, even though it would be as vain to seek them in the very truth of things, or in bodies that actually exist, as it would be to seek the things that geometers invent by mathematical abstraction (§§38-39, tr. Clarke, boldface added).

The comparison of physics to geometry in §38 is Newton’s (see Janiak 59-60), but §39 takes this in a distinctively Berkeleian direction, arguing that forces are no more to be found “in the very truth of things” than length without breadth or other geometrical abstractions. The key point, though, is Berkeley’s assertion that this “is all that a physicist should aim to realize.”

Berkeley’s position here, as in the Principles, is that “mechanical explanation” is a matter of subsumption under general laws (De Motu §37). What is new here is the recognition that these laws cannot be formulated without certain “general and abstract terms” (§7; NB: abstract terms, not ideas), like ‘force’. However, although Newton defines ‘impressed force’ as “the action exerted on a body” by another body (Janiak 80) and Berkeley concedes that “this way of speaking is appropriate for mechanical demonstrations” (De Motu §28), nevertheless Berkeley denies that force involves genuine action, in any metaphysically robust sense. It follows from this picture that “it is the responsibility of the physicist or mechanist to provide only the rules, and not the efficient causes, of impulses or attractions and, in a word, the laws of motion; and once these are established properly, to assign the solution of a particular phenomenon” (De Motu §35). Thus, in a passage that can be read as a commentary on Newton’s discussion of God in the General Scholium, Berkeley writes:

One may conclude from this that the cause of motion and rest is identical with that of the existence of bodies [i.e., God] … To discuss God, however, and the greatest and best creator and conserver of all things, and to demonstrate how all things depend on the highest and true being, although it is the most excellent part of human knowledge, appears to belong to first philosophy or metaphysics and theology rather than to natural philosophy, which today is almost completely restricted to experiments and mechanics. Therefore natural philosophy either presupposes knowledge of God, or it borrows it from some superior science. Nevertheless it is very true that the investigation of nature provides the higher sciences in every way with excellent arguments to show and prove the wisdom, goodness, and power of God (De Motu §34).

Berkeley concludes his book as follows:

In physics, we rely on sensation and experience, which extend only to effects that are perceivable; in mechanics, the abstract notions of mathematics are accepted. In first philosophy or metaphysics, one discusses incorporeal things and the causes, truth, and existence of things … Causes that are truly active can be known to some extent only by reflection and reasoning … The discussion of these causes, however, is reserved for first philosophy or metaphysics. If each science is given the scope that properly belongs to it and its limits are assigned, and if the principles and objects that belong to each one are carefully distinguished, it will be possible to treat each one with greater facility and clarity (De Motu §§71-72).

In other words, Newton ought to have stuck to his original project of “discover[ing] the forces of nature from the phenomena of motions and … demonstrat[ing] the other phenomena from these forces,” since “to treat of God from the phenomena” is not part of natural philosophy (physics or mechanics). True causes, such as God, are the province of metaphysics, a distinct enterprise with distinct methods and tools and, importantly, an enterprise in which the employment of ‘mathematical hypotheses’ like force is illegitimate.

(Cross-posted at blog.kennypearce.net.)

  • I don’t have the book in front of me, but if memory serves this point is made by Lisa Downing.

One of the problems for the traditional ‘Rationalists and Empiricists’ story of early modern philosophy is that it is surprisingly difficult to define ‘rationalism’ and ’empiricism’ appropriately (see here for a previous discussion). One traditional way of drawing the distinction, derived from Locke, is over the existence of innate ideas. This distinction, however, does not capture what is of importance to many other early modern philosophers, and oddly excludes Malebranche and his followers from the rationalist camp. (Since Malebranche holds that no ideas are ever in the human mind—they are all in God—he holds that no ideas are innate to the human mind.) Another traditional way of drawing the distinction, derived from Kant, is over the existence of a priori knowledge. This is perhaps somewhat more promising, for Locke’s critique of innate ideas is presented as a component of a broader critique of innate knowledge. However, most of the philosophers usually classified as empiricists accept at least some a priori knowledge: for instance, in mathematics. Kant would say that the rationalists accept synthetic knowledge a priori, but the analytic/synthetic distinction is a Kantian innovation with no precise parallel in earlier modern philosophers.

An approach which is perhaps more promising, in terms of its ability to connect to explicit subjects of debate in the period is the definition of rationalism in terms of ratio, i.e., reason. The rationalist, on this telling, distinguishes between the faculty of sense/imagination and the faculty of pure reason/intellect. The empiricist collapses them. On this way of drawing the distinction, Cartesianism turns out to be a paradigmatic form of rationalism (good), and Malebrancheans get to be rationalists for the same reason other Cartesians do (also good). Further, Hobbes and Gassendi offer explicit arguments in favor of empiricism in this sense, and Berkeley and Hume appear to presuppose such an empiricism. Still, there are some odd consequences. The question whether Locke is an empiricist turns out, on this approach, to be a difficult interpretive question rather than a straightforward textual one, though Locke does strongly suggest empiricism (in this sense) by his intentional collapse of the distinction between ‘species’ and ‘notions’ (EHU §1.1.8). A stranger consequence (which perhaps suggests that this account should not be pushed back before the mid-17th century) is that the traditional Aristotelian/Thomistic picture turns out to be a form of rationalism, despite holding that “there is nothing in the intellect which is not first in the senses,” since it does affirm a distinction between sensory and intellectual representations.

One more curious feature of this approach (which is the reason I am thinking about it today) is that it turns out that Newton offers an explicit argument for this kind of rationalism in De Gravitatione:*

If anyone now objects that we cannot imagine extension to be infinite, I agree. But at the same time I contend that we can understand it. We can imagine a greater extension, and then a greater one, but we can understand that there exists an extension greater than we can imagine. And here, incidentally, the faculty of understanding is clearly distinguished from imagination (Janiak 38).

Now, in a way this is not surprising. In Descartes (and Plato), as in Newton here, there is considerable evidence that the affirmation of rationalism (in this sense) arises from reflection on the phenomenology of mathematics: many people who have a great deal of experience in mathematics report the experience of encountering an object not revealed by the senses, hence one supposes that there is a faculty of understanding that has objects of its own, distinct from the objects of the senses. Perhaps these objects may be somehow derived from the senses, in a manner consistent with the Aristotelian dictum (“nothing in the intellect that was not first in the senses”) as the Aristotelians interpreted it, or perhaps not. Nevertheless, the idea/notion of extension contemplated by the intellect is unlike anything known by the senses, for the senses know only particular images of extension, all of which are finite.

Hobbes, Berkeley (at least on my reading), and Hume all hold, on the contrary, that this mathematical activity, which may be somehow and in some sense about infinite extension, nevertheless employs, as the mind’s immediate object, only finite determinate sense images. These images, which according to Descartes and his followers are the objects of the faculty of sense/imagination and are not even properly called ‘ideas’, are in fact all the ideas there are. It can be seen now why Locke’s empiricism is somewhat ambiguous: although he rejects the species/notion distinction, whether his abstract ideas are imagistic in this way is highly controversial. One can also see here that Newton’s rationalism (in this sense) is part of a broader tension in the development of physics, which to some degree continues to this day. Galileo, Leibniz, and Newton all insist that a proper approach to physics must be both mathematical and experimental, but math itself is, of course, precisely not experimental. For Newton (at least in De Gravitatione), just as much as for Descartes, many of the fundamental concepts of physics (most notably, in both cases, extension) are mathematical concepts attained by the pure intellect and differing radically from anything perceived by the senses. Yet (against Descartes, in agreement with Galileo and Leibniz) Newton holds that the laws of physics, employing those concepts, must be derived from sensory experience. And of course even Descartes holds that the laws ought to be applicable to what we experience by means of the senses. So there is no obvious contradiction between Newton’s rationalism and his empirical/experimental methodology, but there is an apparent tension, or at least a collection of difficult philosophical questions (which are, again, still very much alive) concerning the very concept of (what we now call) applied math. Though these sorts of questions are by no means absent from (e.g.) Plato, the mathematization of physics through the 17th century suddenly places them among the most important questions in natural philosophy, a role they had not previously occupied.

(Cross-posted at blog.kennypearce.net.)

  • I should note at the outset of this discussion that I am not a Newton specialist and, other than looking at the introduction on the Google preview this morning, have not read this important book on the subject I am about to discuss. I am aware that the relationship of De Gravitatione to Newton’s published works is a vexed question. Blog posts are not journal papers.