Hobbes: Science

I would like to begin by congratulating Arash Abizadeh. Hobbes and the Two Faces of Ethics is a splendid book. Even where I have disagreed with Abizadeh, the book has been a great help to me in framing central issues and in setting out pressing questions for different interpretations. I am sure that it will be a valuable resource for students of Hobbes for many years. -/- Here I will discuss Abizadeh’s views on the science of morality in Hobbes, and (...) I will focus on his Chapter 3. I will begin from the principles that form the basis of that science and proceed to its conclusions, the laws of nature. In both cases, although I recognize the difficulties that Abizadeh has presented for what he calls subjectivism, I am also concerned about the alternative interpretation that he defends. On that interpretation, prudentialism, the view that one ought to desire and pursue one’s own good, is a foundational principle of moral science, which gives us reason to follow the laws of nature. The principle is distinct from any particular desire or knowledge, but its practical importance is guaranteed by epistemic access to the laws of nature: any sane adult can easily know the laws of nature. (shrink)

This paper deals with Hobbes's theory of optical images, developed in his optical magnum opus, ‘A Minute or First Draught of the Optiques’, and published in abridged version in De homine. The paper suggests that Hobbes's theory of vision and images serves him to ground his philosophy of man on his philosophy of body. Furthermore, since this part of Hobbes's work on optics is the most thoroughly geometrical, it reveals a good deal about the role of mathematics in Hobbes's philosophy. (...) The paper points to some difficulties in the thesis of Shapin and Schaffer, who presented geometry as a ‘paradigm’ for Hobbes's natural philosophy. It will be argued here that Hobbes's application of geometry to optics was dictated by his metaphysical and epistemological principles, not by a blind belief in the power of geometry. Geometry supported causal explanation, and assisted reason in making sense of appearances by helping the philosopher understand the relationships between the world outside us and the images it produces in us. Finally the paper broadly suggests how Hobbes's theory of images may have triggered, by negative example, the flourishing of geometrical optics in Restoration England. (shrink)

This paper makes a case for the centrality of the passion of curiosity to Hobbes’s account of human nature. Hobbes describes curiosity as one of only a few capacities differentiating human beings from animals, and I argue that it is in fact the fundamen- tal cause of humanity’s uniqueness, generating other important difference-makers such as language, science and politics. I qualify Philip Pettit’s (2008) claim that Hobbes believes language to be the essence of human difference, contending that Pettit grants language (...) too central a place in Hobbes’s psychology. Language is, for Hobbes, a tech- nology adopted on account of curiosity. Further, curiosity is necessary not only for linguistic but also for scientific activity. Only after what he calls original knowledge has been gathered are names employed to generate the conditional propositions that con- stitute science. Finally, curiosity can resolve another puzzle of Hobbesian psychology that Pettit leaves unanswered: our tendency towards strife. Hobbes believes that inso- far as human beings have an implacable hunger for knowledge of the future, we are unable to rest content with present gains and must always aspire to secure the best possible outcome for ourselves. (shrink)

The history of the Parallelogram Rule for composing physical quantities, such as motions and forces, is marked by conceptual difficulties leading to false starts and halting progress. In particular, authors resisted the required assumption that the magnitude and the direction of a quantity can interact and are jointly necessary to represent the quantity. Consequently, the origins of the Rule cannot be traced to Pseudo-Aristotle or Stevin, as commonly held, but to Fermat, Hobbes, and subsequent developments in the latter part of (...) the seventeenth century. (shrink)

Many of Margaret Cavendish’s criticisms of Thomas Hobbes in the Philosophical Letters (1664) relate to the disorder and damage that she holds would result if Hobbesian pressure were the cause of visual perception. In this paper, I argue that her “two men” thought experiment in Letter IV is aimed at a different goal: to show the explanatory potency of her account. First, I connect Cavendish’s view of visual perception as “patterning” to the “two men” thought experiment in Letter IV. Second, (...) I provide a potential reply on Hobbes’s behalf that appeals to physiological differences between perceivers’ sense organs, drawing upon Hobbes’s optics in De homine. Third, I argue that such a reply would misunderstand Cavendish’s objective of showing the limited explanatory resources available in understanding visual perception as pressing when compared to her view of visual perception as patterning. (shrink)

_ Source: _Volume 30, Issue 1, pp 4 - 27 The _Animadversiones in Elementorum Philosophiae_ by a little known Flemish scholar G. Moranus, published in Brussels in 1655 was an early European response to Hobbes’s _De Corpore_. Although it is has been referred to by various Hobbes scholars, such as Noel Malcolm, Doug Jesseph, and Alexander Bird it has been little studied. Previous scholarship has tended to focus on the mathematical criticisms of André Tacquet which Moranus included in the form (...) of a letter in his volume. Moranus’s philosophical objections to Hobbes’s natural philosophy offer a fascinating picture of the critical reception of Hobbes’s work by a religious writer trained in the late Scholastic tradition. Moranus’s opening criticism clearly shows that he is unhappy with Hobbes’s exclusion of the divine and the immaterial from natural philosophy. He asks what authority Hobbes has for breaking with the common understanding of philosophy, as defined by Cicero ‘the knowledge of things human and divine’. He also offers natural philosophical and theological criticisms of Hobbes for overlooking the generation of things involved in the Creation. He also attacks the natural philosophical underpinning of Hobbes’s civil philosophy. In this paper I look at a number of philosophical topics which Moranus criticised in Hobbes’s work, including his mechanical psychology, his theory of imaginary space, his use of the concept of accidents, his blurring of the distinction between the human being and the animal, and his theories of motion. Moranus’s criticisms, which are a mixture of philosophical and theological objections, gives us some clear indications of what made Hobbes’ natural philosophy controversial amongst his contemporaries, and sheds new light on the early continental reception of Hobbes’s work. (shrink)

This paper examines Hobbes’s criticisms of Robert Boyle’s air-pump experiments in light of Hobbes’s account in _De Corpore_ and _De Homine_ of the relationship of natural philosophy to geometry. I argue that Hobbes’s criticisms rely upon his understanding of what counts as “true physics.” Instead of seeing Hobbes as defending natural philosophy as “a causal enterprise … [that] as such, secured total and irrevocable assent,” 1 I argue that, in his disagreement with Boyle, Hobbes relied upon his understanding of natural (...) philosophy as a mixed mathematical science. In a mixed mathematical science one can mix facts from experience with causal principles borrowed from geometry. Hobbes’s harsh criticisms of Boyle’s philosophy, especially in the _Dialogus Physicus, sive De natura aeris_, should thus be understood as Hobbes advancing his view of the proper relationship of natural philosophy to geometry in terms of mixing principles from geometry with facts from experience. Understood in this light, Hobbes need not be taken to reject or diminish the importance of experiment/experience; nor should Hobbes’s criticisms in _Dialogus Physicus_ be understood as rejecting experimenting as ignoble and not befitting a philosopher. Instead, Hobbes’s viewpoint is that experiment/experience must be understood within its proper place – it establishes the ‘that’ for a mixed mathematical science explanation. (shrink)

_ Source: _Volume 29, Issue 1, pp 66 - 85 This paper will deal with the notion of _conatus_ and the role it plays in Hobbes’s program for natural philosophy. As defined by Hobbes, the _conatus_ of a body is essentially its instantaneous motion, and he sees this as the means to account for a variety of phenomena in both natural philosophy and mathematics. Although I foucs principally on Hobbesian physics, I will also consider the extent to which Hobbes’s account (...) of _conatus_ does important explanatory work in his theory of human perception, psychology, and political philosophy. I argue that, in the end, there are important limitations in Hobbes’s account of _conatus_, but that Leibniz adapted the concept in important ways in developing his science of dynamics. (shrink)

_ Source: _Volume 29, Issue 1, pp 9 - 38 Hobbes tried to develop a strict version of the mechanical philosophy, in which all physical phenomena were explained only in terms of bodies in motion, and the only forces allowed were forces of collision or impact. This ambition puts Hobbes into a select group of original thinkers, alongside Galileo, Isaac Beeckman, and Descartes. No other early modern thinkers developed a strict version of the mechanical philosophy. Natural philosophies relying solely on (...) bodies in motion require a concept of inertial motion. Beeckman and Descartes assumed rectilinear motions were rectilinear, but Galileo adopted a theory which has been referred to as circular inertia. Hobbes’s natural philosophy depended to a large extent on what he called “simple circular motions.” In this paper, I argue that Hobbes’s simple circular motions derived from Galileo’s belief in circular inertia. The paper opens with a section outlining Galileo’s concept, the following section shows how Hobbes’s physics depended upon circular motions, which are held to continue indefinitely. A third section shows the difficulty Hobbes had in maintaining a strictly mechanistic philosophy, and the conclusion offers some speculations as to why Galileo’s circular inertia was never entertained as a serious rival to rectilinear inertia, except by Hobbes. (shrink)

_ Source: _Volume 29, Issue 1, pp 39 - 65 Since Euclid, optics has been considered a geometrical science, which Aristotle defines as a “mixed” mathematical science. Hobbes follows this tradition and clearly places optics among physical sciences. However, modern scholars point to a confusion between geometry and physics and do not seem to agree about the way Hobbes mixes both sciences. In this paper, I return to this alleged confusion and intend to emphasize the peculiarity of Hobbes’s geometrical optics. (...) This paper suggests that Hobbes’s conception of geometrical optics, as a mixed mathematical science, greatly differs from Descartes’s one, mainly because they do not share the same “mechanical conception of nature.” I will argue that Hobbes and Descartes also have in common the quest for a different kind of geometry for their optics, different from that of the Ancients. I will show that this departure is not recent since Hobbes’s approach is already evident in 1636, when he judges the demonstrations of his contemporary friends, Claude Mydorge and Walter Warner. Finally the paper broadly suggests what is noteworthy in Hobbes’s optics, that is, the importance of the idea of force in his mechanics, although he was not able to conceptualize it in other terms than “quickness.”. (shrink)

_ Source: _Volume 29, Issue 1, pp 86 - 102 The aim of this paper is to give an overview of the place that Hobbes assigns to optics in the context of his classification of sciences and disciplinary boundaries. To do this, I will begin with an account of Hobbes’s conception of philosophy or science, and particularly his distinction between true and hypothetical knowledge. I will also show that in his demarcation between mathematics or geometry and natural philosophy Hobbes was (...) influenced by Galileo’s _Dialogue_. I then analyse the consequences of this distinction for optics, and conclude by clarifying its status among the scientific disciplines. (shrink)

We do not generally take the Hobbesian project to be one that encourages human flourishing. I will argue that it is; indeed, I will propose that Hobbes attempts the first modern project to provide for the possibility of the diversity of human flourishing in the civil state. To do so, I will draw on the recent work of Donald Rutherford, who takes Hobbes to be a eudaimonist in the Aristotelian tradition.

Accounts of Hobbes’s ‘system’ of sciences oscillate between two extremes. On one extreme, the system is portrayed as wholly axiomtic-deductive, with statecraft being deduced in an unbroken chain from the principles of logic and first philosophy. On the other, it is portrayed as rife with conceptual cracks and fissures, with Hobbes’s statements about its deductive structure amounting to mere window-dressing. This paper argues that a middle way is found by conceiving of Hobbes’s _Elements of Philosophy_ on the model of a (...) mixed-mathematical science, not the model provided by Euclid’s _Elements of Geometry_. I suggest that Hobbes is a test case for understanding early-modern system-construction more generally, as inspired by the structure of the applied mathematical sciences. This approach has the additional virtue of bolstering, in a novel way, the thesis that the transformation of philosophy in the long seventeenth century was heavily indebted to mathematics, a thesis that has increasingly come under attack in recent years. (shrink)

This paper focuses on an understudied aspect of Hobbes's natural philosophy: his approach to the domain of life. I concentrate on the role assigned by Hobbes to the heart, which occupies a central role in both his account of human physiology and of the origin of animal locomotion. With this, I have three goals in mind. First, I aim to offer a cross-section of Hobbes's effort to provide a mechanistic picture of human life. Second, I aim to contextualize Hobbes's views (...) in the seventeenth-century debates on human physiology and animal locomotion. In particular, I will compare Hobbes's views with the theories put forth by Harvey, Descartes, the Galenic, and Peripatetic traditions. Also, I will show that Hobbes was receptive to advances within contemporary English physiology and chemistry. Third, by means of a comparison with Descartes, I advance some hypothesis to explain why Hobbes indentified the heart, and not the brain (as was increasingly com... (shrink)

I offer an alternative account of the relationship of Hobbesian geometry to natural philosophy by arguing that mixed mathematics provided Hobbes with a model for thinking about it. In mixed mathematics, one may borrow causal principles from one science and use them in another science without there being a deductive relationship between those two sciences. Natural philosophy for Hobbes is mixed because an explanation may combine observations from experience (the ‘that’) with causal principles from geometry (the ‘why’). My argument shows (...) that Hobbesian natural philosophy relies upon suppositions that bodies plausibly behave according to these borrowed causal principles from geometry, acknowledging that bodies in the world may not actually behave this way. First, I consider Hobbes's relation to Aristotelian mixed mathematics and to Isaac Barrow's broadening of mixed mathematics in Mathematical Lectures (1683). I show that for Hobbes maker's knowledge from geometry provides the ‘why’ in mixed-mathematical explanations. Next, I examine two explanations from De corpore Part IV: (1) the explanation of sense in De corpore 25.1-2; and (2) the explanation of the swelling of parts of the body when they become warm in De corpore 27.3. In both explanations, I show Hobbes borrowing and citing geometrical principles and mixing these principles with appeals to experience. (shrink)

This essay examines Hobbes’ philosophy of space, with emphasis placed on the variety of interpretations that his concept of imaginary space has elicited from commentators. The process by which the idea of space is acquired from experience, as well as the role of nominalism, will be offered as important factors in tracking down the elusive content of Hobbes’ conception of imaginary space.

There is no doubt about considering Thomas Hobbes as one of the most radical shields of XVII century mechanistic materialism, which explains phenomena according to laws of bodily motion. Agreeing to such an explicatory system, every single movement is caused by an external one, which implies that there is neither a self-moving body nor a body whose cause of motion is itself. However, a main idea is conceived by Hobbes himself, namely, the consideration of a vital or animal motion in (...) certain bodies. Is such a suggestion about qualitative difference between bodies? Are animated bodies able to be grounded to equal explicatory principles of mechanism? William Harvey's blood circulation and heart beating claims allow us to safeguard the Hobbes' theory coherence. (shrink)

At the beginning of the seventeenth century, the sine law of refraction had been discovered. Thus, natural philosophers tried even more to find a cause of refraction and to demonstrate the law. One of them was Thomas Hobbes, who was the author of the Leviathan and also worked on optics. At first, in the Hobbes analogy , he was influenced by Ibn al-Haytham, just as Descartes was in his famous proof in the Dioptrique . In his later optical scripts Tractatus (...) Opticus I , Tractatus Opticus II , and A Minute or First Draught of the Optiques , he developed a new explanation. Rejecting a corpuscular theory of light, Hobbes conceived a ray not as a body but as a motion originating from the light source: a ray can only be the motion of a body. The normal to the sides of a ray is called 'linea lucis'. If a ray is incident into another medium with a different density, one part of the linea lucis will be in the rarer and the other in the denser medium during an imperceptibly short period. Because the resistances in the two media are different, the parts of the linea lucis will move with different velocities; as a result the linea lucis will rotate and the direction of the ray will be changed. The next explanation given in De Corpore comes closer to the first one that Hobbes set down in the analogy. It must be asked why he replaced the theory of rotation by one which seems to carry less conviction. The reason could be that the dropped theory is founded in part on basic requirements of a corpuscular theory of light. Abandoning the whole theory might have been the lesser evil for Hobbes. In two later works, the Problemata Physica and the Decameron Physiologicum , Hobbes varied his explanation without giving any proof for the sine law. It should be noted, however, that in the Decameron he refers to the proof contained in the Tractatus Opticus I, but not that given in De Corpore. (shrink)

In the field of astronomy, Thomas Hobbes's mechanistic philosophy was influenced by Johannes Kepler. Whereas Galilei still sticks to the circular motion of the planets, Hobbes takes over the Keplerian ellipses. According to Kepler, he defines astronomy as ' celestial physics'. As a consequence, he tries to determine the cause for the planetary motion and the reason why the orbit of the earth is eccentric. Hobbes modifies Kepler's explanation given in the Epitome astronomiae Copernicanae that the earth consists of two (...) parts: one well-disposed, the other hostile towards the sun. Referring to this doctrine, Hobbes developed various astronomical theories throughout a time span of about 35 years in works like "De motu" , De corpore , and the "Decameron physiologicum". (shrink)

Many critics, Descartes himself included, have seen Hobbes as uncharitable or even incoherent in his Objections to the Meditations on First Philosophy. I argue that when understood within the wider context of his views of the late 1630s and early 1640s, Hobbes's Objections are coherent and reflect his goal of providing an epistemology consistent with a mechanical philosophy. I demonstrate the importance of this epistemology for understanding his Fourth Objection concerning the nature of the wax and contend that Hobbes's brief (...) claims in that Objection are best understood as a summary of the mechanism for scientific knowledge found in his broader work. Far from displaying his confusion, Hobbes's Fourth Objection in fact pinpoints a key weakness of Descartes's faculty psychology: its unintelligibility within a mechanical philosophy. (shrink)

Thomas Hobbes's doctrine of space is here considered as an example of the Nachzuirkung of Jesuit commentaries on Aristotle's natural philosophy in seventeenth-century mechanistic science. Hobbes's doctrine of space can be reconstructed in terms of his intensive dialogue with late scholasticism, as represented in the works of several important Jesuit authors. Although he presents his concept of space as an alternative to the Aristotelian notion of place, there are some remarkable similarities between Hobbes's alternative notion of space and the concept (...) of spatium imaginarium, found in the Jesuit commentaries. While Hobbes adopts many scholastic elements, he employs these to his own purposes. Thus, on the one hand, this article does not so much challenge Hobbes's "modernity", but rather tries to put it in its proper perspective. On the other hand, it tries to show the vitality and importance of Jesuit natural philosophy in non- or even anti-Aristotelian contexts. (shrink)

At the beginning of the seventeenth century, the sine law of refraction had been discovered. Thus, natural philosophers tried even more to find a cause of refraction and to demonstrate the law. One of them was Thomas Hobbes, who was the author of the Leviathan and also worked on optics. At first, in the Hobbes analogy, he was influenced by Ibn al-Haytham, just as Descartes was in his famous proof in the Dioptrique. In his later optical scripts Tractatus Opticus I, (...) Tractatus Opticus II, and A Minute or First Draught of the Optiques, he developed a new explanation. Rejecting a corpuscular theory of light, Hobbes conceived a ray not as a body but as a motion originating from the light source: a ray can only be the motion of a body. The normal to the sides of a ray is called 'linea lucis'. If a ray is incident into another medium with a different density, one part of the linea lucis will be in the rarer and the other in the denser medium during an imperceptibly short period. Because the resistances in the two media are different, the parts of the linea lucis will move with different velocities; as a result the linea lucis will rotate and the direction of the ray will be changed. The next explanation given in De Corpore comes closer to the first one that Hobbes set down in the analogy. It must be asked why he replaced the theory of rotation by one which seems to carry less conviction. The reason could be that the dropped theory is founded in part on basic requirements of a corpuscular theory of light. Abandoning the whole theory might have been the lesser evil for Hobbes. In two later works, the Problemata Physica and the Decameron Physiologicum, Hobbes varied his explanation without giving any proof for the sine law. It should be noted, however, that in the Decameron he refers to the proof contained in the Tractatus Opticus I, but not that given in De Corpore. (shrink)