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Mechanical Philosophy: with the overall rejection of causes in nature other Reductionism and than material and efficient causes. Hence reduc- Foundationalism tionism should be understood as a strategy of explanation rather than necessitating particular Tzuchien Tho ontological commitments. Department of Philosophy, University of Bristol, While reduction to a brute entity or a series of Bristol, UK fundamental elements can be traced back to the pre-Socratics, foundationalism, as we understand Related Topics it, is more exclusively associated with the emer- Mechanical philosophy · Reductionism · gence of modern philosophy. While reductionism Foundationalism · Demonstrative knowledge · is ancient, foundationalism, on the other hand, is Atomism · Experimental philosophy · more exclusively associated with the emergence Rationalism · Empiricism · Scepticism of modern philosophy. Although the term is not an (Skepticism) · Laws of motion actor’s category, thinkers such as Descartes sought to overcome the threat of (self-imposed) hyperbolic skepticism through the establishment Introduction of foundational knowledge. However, earlier theories of knowledge such as what we find in Reductionism, the mode of natural explanation the Aristotelian-scholastic tradition could also be which reduces complex phenomena (including called “foundationalist” in the sense that it sets up mental phenomena) to simple and epistemically a hierarchy for the degrees of knowledge, where or ontological brute entities or sensibles, is not an we move from less certain ways of knowing and exclusively modern trend. All pre-Socratic philos- move “up” to apodictic knowledge ophers are known through their various proposals (demonstrative) which achieves the highest and for a reductionist ontology (i.e., water, indivisi- most certain form. We find in early modern bles, four fundamental elements, etc.). Reduction- foundationalist thinking, borrowing from the ism in modern philosophy is often understood as image of Euclidian demonstration, an inverted the sine qua non of mechanical philosophy. hierarchy that moves from the ground of a small Among the various sects of this general theoreti- number of certain knowledge to more complex cal tendency in the early modern period however, forms. The key difference here is that Aristotelian to what a reductionism would reduce was a matter knowledge works “up” toward certainty where of much debate. Yet some of the common moti- Cartesianism is grounded “down” in certainty. vation among these tendencies can be identified Of course, Descartes and Aristotle share a

© Springer Nature Switzerland AG 2020 D. Jalobeanu, C. T. Wolfe (eds.), Encyclopedia of Early Modern Philosophy and the Sciences, https://doi.org/10.1007/978-3-319-20791-9_142-1 2 Mechanical Philosophy: Reductionism and Foundationalism common recognition of geometrical demonstra- to provide conditions beyond mere geometrical tion as apodictic. However, Descartes grounds relationships.) However, for a broad number of knowledge on the clearness and distinctness of key mechanists like Gassendi and Boyle, this ideas, of which geometrical certainty is a paradig- convergence does not follow. For a standard set matic case. Hence complex forms of knowledge of canonical thinkers in the tradition, it is ontolog- are certain if they are rooted in the solid founda- ical reductionism rather than epistemic tion of fundamental axiom-like clear and distinct foundationalism that most characterizes this pro- ideas. Hence, while reductionism was a strategy ject of mechanical philosophy. of explanation, foundationalism was a method of The standard identification of mechanical phi- knowledge. losophy with materialism and atomism This entry will address the unique confluence (understood by some scholars as one and the of reductionism and foundationalism in the same for the pre-modern and early modern period) mechanical philosophy of the early modern is not entirely mistaken. The term “mechanical period. The result of this confluence of a mode philosophy” was first used by H. More and of explanation with a method of knowledge is that R. Boyle (Hattab 2011; Anstey 2000). While only reduction to mechanical principles consti- Boyle did not make any ultimate commitment to tutes well-founded knowledge. However some indivisibles, the project of “mechanical or corpus- thinkers within the tradition also sought to undo cular philosophy” was rooted in the use of atom- the restrictive implications of this confluence istic hypotheses as a means of designating the without rejecting the first fruits of the mechanistic proper domain of natural explanation even when program. the authors were not fully committed to indivisi- bles (Pyle 1995; Boyle 1999, I, 474). (The relation between a hypothetical commitment to atomism The Internal Problems of Reductionist and the legitimacy of mechanical philosophy in Explanation in Mechanical Philosophy Boyle has been litigated between A. Pyle, A. Clericuzio, P. Anstey, and A. Chalmers in a We have indicated above that reductionism and series of corresponding articles. See Anstey 2002; foundationalism are different aspects at work in Chalmers 2002; Clericuzio 1990, 2000; Pyle early modern natural philosophy. In the case of 2002, 2018.) However, if we expand the term Descartes, these are distinct but mutually “mechanical philosophy” to a wider set of figures supporting projects: the reduction of the natural to include the Italian contingent featuring world to its ontological basis in extended sub- Guidobaldo del Monte, Galileo, and the Galilean stance (res extensa) is in deep sympathy with the school, the atomistic doctrine cannot be consid- foundation of knowledge in clear and distinct ered a necessary aspect of the reductionist posi- ideas. Since geometry is a priori and based on tion (Garber 2002). “Mechanics” in this tradition clear and distinct ideas, the reduction of physical prescribes a form of explanation that reduces to reality to instantiated geometrical relations allows the five (or six) classical machines (Guidobaldo for a convenient convergence of reductionism and 1577, cited in Garber 2002). foundationalist epistemology. Though Cartesian Understanding God as the divine artificer of a matter (res extensa) is inert, the laws of material complex machine (the world) was not uncommon interactions and transformation are sustained by for all sects of the mechanical tradition. However, God’s decree, concurrence, and conservation this view does not have to imply anything about (AT VIII, 61; CSM I, 240; Arthur 2007). The the ultimate constituents of reality. (The term official view here is that there is simply nothing “mechanistic philosophy” may now seem a bit other than geometrical truths to be known about nominalistic between those who self-professed the nature of extended beings. (This is compli- and those whom later historians called “mecha- cated by the ambiguous account of the laws of nistic.” We make the distinction while tarrying nature in the Principia Philosophiae which appear with the ambiguity. See Boudri 2002.) Insofar as Mechanical Philosophy: Reductionism and Foundationalism 3 reductionist explanation does not have to commit phenomena outside of spatial ones. While matters to entities at the irreducible level of reality, the like spatial position and locomotion (change in reduction to mechanical aggregates can serve as place) can be geometrically explained through fun- the models for the explanation of phenomena. damental constituents or parts mechanically Nonetheless, this view does incur the ultimate arranged, properties like heat, color, and even theoretical burden of implying that motion must weight (or mass) require further elaboration. This be an extramundane input to nature. Like any was a problem with little straightforward agree- machine, what is arranged is bodies. This does ment among the mechanical philosophers. not imply that the machine is operative through Prominent atomists like Gassendi and Boyle, some internal principle as atomists like Gassendi though differing in their commitment to the view, held or according to the Leibnizian theory of did appeal to features of atoms that should be immanent “living force.” The Aristotelian tradi- understood as qualities or principles independent tion affirmed natural motions and places due to of their indivisibility. Most intuitively, color is causes (final and formal) that mechanists saw as interpreted as a sensory effect of the texture of occult and illegitimate. The actuality of an imma- indivisibles. More problematically, the property nent principle of motion in nature remained a of heat was speculated to be reducible to the debate in this domain well into the eighteenth “calorific” or “frigorific” atoms which may reside century. The use of reductionistic mechanism in in particular bodies (Gassendi 1658, I, 394–401; the life sciences where immanent organic growth Boyle 1999, IV, 380–381). (As ever, Boyle is (the preeminent form of Aristotelian motion) was skeptical of this possibility but seriously main- seemingly irreducible also remained an abiding tains the hypothesis for experimental purposes. difficulty (Des Chene 2001; Hutchins 2015; See Pyle 2018.) The danger here is that this view Baldassarri 2019). Nonetheless Descartes’ affir- reintroduces the Aristotelian appeal to principles mation of reductionism and foundationalism was and essences that the reduction to atoms was consistent on this account. Matter was inert and supposed to avoid. Of course we cannot expect motion only exists through an external mover historical authors to have “purified” their writing (God). to the retrospective standards of the historian of Hence while materialism and corpuscularianism thought. This issue however does identify a recur- can be legitimately understood as a key doctrine ring problem of this atomistic version of mechan- among the mechanical philosophers, it is not a ical reductionism. With generosity, Boyle does necessary feature of this approach to explanation provide a suitable answer to this question by (Dijksterhuis 1969). Reductionism does not have distinguishing between the universal matter of to be either complete or go “all the way” to the atoms and their transmutation into various ultimate metaphysical constituents of reality but forms. Appealing to the tradition of alchemy, he only to the functional aspects of nature, analogous argues that orderly transmutations of “one com- to machines of art, responsible for its basic mon matter” can give rise to the variation of operation. principles inherent in bodies as composites For the atomists among the mechanistic philos- (Boyle 1999, III, 13). This view is not entirely ophers, reductionist explanation was a reduction to free from the elemental principles of Aristotelian- atoms or corpuscles. This view constitutes a main- ism but does provide enough to justify the plausi- stream of mechanistic philosophy that reduces bility of universal reduction. physical explanation to fundamental entities. In The irreducibility of qualitative principles its most fundamental aspect, the spatiality of bodies among the atomists has a counterpart among the is accounted for by the spatiality of their funda- nonatomists. Thinkers like Descartes and Hobbes mental constituents. This aspect is continuous with held a sister concept to atomism. With self- historical atomism from classical sources. How- described corpuscularianism, they rejected the ever, the explanation of physical properties explicit doctrines of atomism and traditional requires further properties of observable accounts of the void and the indivisible entity. 4 Mechanical Philosophy: Reductionism and Foundationalism

From them, nature was reducible to explanations The Synthesis of Reductionism and based on size, shape, and motion. However, this Foundationalism reduction did not require the further ontological basis to ultimate indivisibles. In relation to the As we have identified above, many modern natu- former problem, Descartes was explicitly clear ral philosophers embraced reductionism as the that qualitative properties like heat and moisture legitimate means to provide explanation for phys- were due only to the motion of bodies (AT XI, ical phenomena. By appealing to earlier tradi- 25–26, CSM I 89; AT XI 33, CSM 191). This tions, atomists sought to reduce natural reliance on a minimalist ontology also involved explanation to the properties and behavior of indi- some gaps of explanation. What was lacking, as visibles. Nonatomists sought to reduce natural the later Leibniz and Newton would point out, is explanation to the size, shape, and motion of the principle of resistance in the interaction bodies whether these reduce to indivisibles, between bodies. In the case of Descartes and some other kind of thing, or whether they reduce Hobbes, the reduction of physical phenomena to at all. As we have seen, a reductionist approach to size, shape, and motion implies that the phenom- explanation does not have to go “all the way” to enon of resistance and elasticity of bodies can primary constituents. Appealing to Guidobaldo only be accounted for by externally imposed prin- Del Monte, the reduction to composed machines ciples of interaction (such as the laws of collision may be a more sensible way to identify what was in Principia Philosophiae and its similar but alter- so “mechanical” about the so-called mechanists native version in De Corpore). Hence while Des- (Guidobaldo 1577). This characterization opens cartes and Hobbes explicitly disagreed on the laws up an important question. If the nonatomists did of motion (and its definition), they agreed on the not appeal to the fundamental entity, what grants rejection of any inherent property in matter irre- the certainty of reduction? In thinkers like Des- ducible to external spatial relations (i.e., geomet- cartes, the reductionist strategy was the conse- rical properties). Resistance and elasticity do not quence of a foundationalist theory of ideas. We emerge from the inherent properties of bodies shall examine this point here. themselves. This provided much fodder for later Among the mechanical philosophers, we find physical theorists of collision (Murray et al. two main themes in the theory of ideas (or theory 2011). (Later critics of Descartes on elasticity of knowledge). The first is the Baconian-inspired include C. Huygens, G.W. Leibniz, I. Newton, experimental method based on induction and the E. du Ch^atelet, etc.) Descartes’ fundamental errors dynamic fallibilist interplay of empirical observa- in his laws of collision provide the occasion for tion and rational taxonomy. The second is the the disputation of whether an internal force of Cartesian method, often called “rationalist,” that resistance (a proto-inertia concept) was necessary roots knowledge on the a priori clearness and for physics (Gabbey 1971; Bernstein 1981). How- distinctness of ideas. Of course these two tradi- ever, the empirical errors of Descartes’ laws were tions are not exclusive; Descartes himself claims a not logically due to the reductionistic view itself. debt to Bacon as do other canonical “rationalists” Certainly, a more accurate account of inertial force such as Leibniz. Conversely the Lockean program could have been defended without the adoption of of the theory of ideas is also deeply the metaphysics of “inherence” (e.g., the modern foundationalist insofar as it is rooted in the basis theory of inertial mass). Nonetheless, later of sense certainty eschewing the a priori basis of thinkers such as Leibniz and Newton argued that clearness and distinctness. Nonetheless, as we some internal force of resistance (vis insita)or move to the later part of the modern period, elasticity must be understood as a key participant these two traditions move further apart. In in physical phenomena such as collision and (for Leibniz’s polemical disputation of Locke’s An Newton) attraction. Essay Concerning Human Understanding,we see the maturation of one corner of this debate regarding the plausibility of “innate ideas,” a Mechanical Philosophy: Reductionism and Foundationalism 5 parting of ways that becomes rigid by the time of as Locke distinguishes primary and secondary Wolff and Kant. Nonetheless, it is important to qualities in perception (the epistemic chain), the highlight the variation in the bottom-up real essences of things are, as a practical matter, foundationalism that characterizes modern ultimately inaccessible (Locke Essay III, 6, 2). philosophy. For the Descartes of the Meditations, the irre- ducibility of mind to matter grants matter a clear The Independence of Reductionism and and distinct nature as res extensa. The reduction of Foundationalism physical qualities to the clear and distinct res extensa, without any further commitment to In the work of Leibniz, we find another kind of atoms or other substantial qualities, is grounded response to this issue of reductionism, in this epistemic criterion. In the Principia foundationalism, and their relation. The most Philosophiae, Descartes provides a more positive important thing to highlight here is the account of the substantial nature of res extensa. relativization of levels of explanation that we Although the logical development of the text find in his work. In the strict interpretation of implies that neither mind nor matter could stand mechanical philosophy, a physical phenomenon independently of the divine, material substance is has to be merely reduced to its functional parts identifiable as a kind of instantiated geometry, interpreted “mechanically” rather than ultimately. determined only by spatial qualities. Further prop- (Needless to say, the adult Leibniz never adopted erties of impenetrability, surface properties, elas- atomism even though he claims to have been an ticity, and the like are relegated to modal adherent in his early youth. GP III 620.) The secondary features emergent from size, shape, natural philosophy of Leibniz follows in this tra- and motion. From this position, we can see that dition, affirming broadly materialistic explana- reductionism is implied in Descartes’ theory of tions based solely on aggregated bodies and ideas (the criterion of certainty) rather than having efficient causality (Leibniz, Specimen an independent motivation. Dynamicum, GM IV, 234–253, AG 117–138). It could be conversely argued that However, Leibniz also affirmed that these foundationalism does not have to include any accounts are embedded in a broader family of reduction. This is most apparent in the later tran- causal relations, including teleological causation scendental philosophers of the German tradition. that was eschewed by his contemporaries. His However we can already see this view at work in famous assertion that it is living force (measured Locke. Locke’s writings are shot through with by mv^2) that is universally conserved in nature Baconian experimentalism. Yet, with explicit Car- (instead of merely the conservation of the quantity tesian inspiration, Locke’s epistemology was sys- of motion mv) is based on what he argued to be tematically empiricist (a rejection of innate ideas), “perceptible by the mind alone” beyond mere based on simple and complex ideas produced in empirical observation or reduction to external the mind by sensory experience. The system is geometrical relations (GM VI 241, AG 125). complex but well-known. For Locke, the founda- The contemporary reader may rightfully wonder tion of knowledge on the certainty of simple ideas why the conservation of energy (for which living does not have to imply either atomism or any force qua mv^2 is an archaic form) could be other ontological reduction (Locke Essay IV, 3, understood as metaphysically beyond other fea- 11). The program of ontological reduction in nat- tures of observable physical properties. There are ural explanation is entertained by Locke but not many subtleties here, but Leibniz interprets living necessitated by the foundational chain of mental force, within the framework of seventeenth- association that connects simple to complex ideas. century physics, as incompatible with any theory Explanation is, in the tradition of Locke, episte- rooted in the inertness of extended substance. mic in character and, hence, in line with the Hence Leibniz accepts the rational legitimacy of fallibilist experimentalist tradition. Hence even 6 Mechanical Philosophy: Reductionism and Foundationalism explanation through reduction but rejects its ▶ Mechanical Philosophy: Mechanics fundamentality. ▶ Mechanical Work Leibniz introduces a relativization of explana- ▶ Mechanism and Chemistry in Early Modern tory frameworks. On one hand, material entities Natural Philosophy and efficient causation are sufficient to provide a ▶ Mechanism: 18th-Century German Philosophy mathematical account of corporeal motion. On ▶ Newton and Leibniz another hand, the theory of living forces provides an additional layer by identifying the conserved quantity in corporeal motion. 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