1 Introduction

According to the traditional reading, Bacon claimed that scientists should approach scientific research without preconceived notions and theoretical presuppositions. Scientific propositions are to be derived from observations and experiments using inductive inference. In recent decades, scholars have mined Bacon’s work to discover that he did develop a natural philosophy, without deriving it from phenomena. Moreover, this theory was present throughout his various writings, both in his early work before the Novum Organum, published in 1620, and in the natural histories written towards the end of his life.

Rees (1977; 1980; 1996) was one of the first leading scholars to highlight Bacon’s matter theory. According to his account, Bacon’s theory can be considered as a particular kind of alchemy. It distinguishes between two kinds of matter: tangible and pneumatic. Pneumatic matter, or ‘spirits’, can be attached to tangible matter, appear in an impure form, or become free of tangible matter. When they are attached to tangible matter, spirits are responsible for most observable changes in nature and introduce active principles that govern material transformations.

Bacon’s theory of matter was influenced by Paracelsian alchemy and the distinction between sulphuric and mercurial substances. According to Bacon, each of these fundamental substances forms a quaternion, depending on the region where substances are found: subterranean, terrestrial, sublunar and planetary. Rees claimed that Bacon also deemed intermediaries between sulphur and mercury to provide explanatory resources, forming three fundamental quaternions to explain all material processes.

Rees’s account generates a tension with the traditional reading of Bacon’s method. How does Bacon’s matter theory cohere with his claim that scientific propositions ought to be derived from observations and experiments? His theory does not seem to have been vetted based on careful observations; rather, he seems to have arrived at his matter theory prior to his work on scientific method. Rees (1977) argues that Bacon’s chemical philosophy “relies heavily on relatively undisciplined conjecture and seems to fly in the face of the procedural recommendations for which Bacon gained posthumous fame (and notoriety)” (Rees 1977, 118).

Perhaps the tension between Bacon’s speculations on matter theory and his method could be reconciled at a different level. Underlying Bacon’s alchemy was a more fundamental view of matter, which could be described as an appetitive form of corpuscularianism. Ancient atomist theories, such as those of Democritus and Epicurus, considered atoms to be mostly inert objects capable of mechanical forces of push and shove, perhaps adding a tendency to more downwards or, in Epicurean theory, a sudden ‘swerve’ that disrupts the regular motion of bodies. In contradistinction with ancient atomism, Bacon thought that the ultimate particles of matter are endowed with active ‘appetites’,Footnote 1 or certain inclinations introduced into atoms that generate ‘motions’, i.e., certain transformations that bodies undergo.Footnote 2

Manzo (2001) argued that Bacon used the notion of ‘subtlety’ to refer to the Democritean method of ‘dissecting’ nature and searching for the hidden structures and ultimate parts of matter, but also to the hidden virtues leading to material transformation, i.e., an alchemical theory of change. Manzo (1999) showed that Bacon endorsed the conservation of quantity of matter. Moreover, she claimed that Bacon based this principle on Biblical sources reinforced by Greek mythology. Manzo (2016) reconstructed Bacon’s theory of natural appetites, which are analogous to the appetites that explain human motives for action.Footnote 3 According to this theory, all matter is endowed with appetites that either tend towards the preservation and the ‘good’ of the individual part, or such that tend towards the preservation of the whole of which the material object is part. Individual appetites are divided into ‘passive’ and ‘active’. Corresponding to the appetites of matter are ‘motions’—i.e., particular types of transformation induced by the appetites. Motions are either ‘simple’, i.e., transformations introduced by universal appetites that exist in all matter, or ‘complex’, i.e., stemming from a combination of two or more appetites. Complex motions can be the result of ‘conflicting’ appetites—where some appetites may be more pronounced due to a particular configuration of the corpuscles. Alternatively, an equilibrium might form, where two opposing appetites result in a seemingly stationary state.

Giglioni (2016b) clarified that Bacon’s theory placed at the centre of his account the simple motions that formed the basis of his matter theory. The motions that result from the appetites in matter ought to explain all natural phenomena. Thus, Giglioni claimed that “it would be more correct to say that Bacon’s philosophy contained a metaphysics of motions rather than of substances” (Giglioni 2016b, 63). Bacon’s atomism is more functional, given that dynamic principles are more important to him than is the particular structure a body possesses at a particular time. The units that constitute Bacon’s alphabet of nature are the simple motions of matter (Giglioni 2016b, 63). Like Manzo, Giglioni thinks that the metaphysics of appetites ultimately rests on Bacon’s theology. Thus, like Rees, who takes Bacon’s matter theory to be speculative, deriving his theory from conjecture, Manzo and Giglioni think that Bacon’s appetitive physics is mostly derived from theological and philosophical motivations.

Bacon’s appetitive physics may be reconciled with Rees’s account of Bacon’s alchemy. It is reasonable to assume that the qualities associated with mercury and sulphur would be reducible in Bacon’s mind to some fundamental appetites or a combination thereof. Bacon thinks that scientific inquiry may involve different levels of generality. Perhaps a more restricted analysis pertains to the study of inclinations exhibited by composite substances, whose internal structure and manifestation of simple motions are not yet known. This study may cover a broad range of phenomena, but would not yet reveal the fundamental appetites that give rise to these inclinations of composite systems. Thus, we can see that Bacon’s appetitive physics is entirely consistent with his alchemy. However, Rees’ concern remains: how does one reconcile Bacon’s theoretical speculations with his inductive method? Apparently, his theory of matter should be labelled as an idol of the theatre, a theory introduced by a priori speculation rather than a scientific proposition derived from phenomena.

One way to resolve this tension is to claim that Bacon must have thought that his appetitive physics was derived from phenomena using careful observation and experimentation. But Jalobeanu (2013; 2015) claims that Bacon’s appetitive physics provides a theoretical background for his experimental work. She demonstrates how in the Latin natural histories, theoretical questions concerning the nature of appetites and inclinations of spirits—which Bacon holds responsible for most of the transformations in nature—guide him in constructing experiments and in revising experimental designs to explore new phenomena. In Jalobeanu’s (2015) account, Bacon’s theory of matter guides experimental work and provides a framework for investigating nature: the experimenter’s task is “to ‘measure’ the relative quantities of spirits and matter and to find ways to ‘measure’ the actions and effects of all the appetites, desires and motions of spirits” (Jalobeanu 2015, 259).Footnote 4 Thus, rather than being derived from observations and experiments, Bacon’s appetitive physics points out the type of experiments that one ought to construct. Thus, one should perhaps think of Bacon as practising a hypothetico-deductive method, despite professing to follow an inductive one.Footnote 5

Garber (2021) speculates that Bacon’s appetitive physics amounts to what he calls ‘methodological anticipations’ or that it is ‘methodological a priori’. According to him, the theory amounts to some necessary presupposition without which a directed research cannot be performed. But Garber’s approach does not make clear why Bacon’s a priori theories about matter do not amount to hypotheses that are then confirmed or refuted. In short, it is not clear from this account why Bacon’s method does not simply amount to a hypothetico-deductive method, circumventing the need to use induction and generalize from particular observation statements to theoretical propositions.

Our task in this paper is to resolve the tension between Bacon’s commitment to his theory of matter and his inductivism. This will be enabled not by showing how his theory is derived from empirical evidence, but by revising our philosophical understanding of induction. One reason it is difficult to reconcile Bacon’s matter theory and inductivism is that as twentyfirst century commentators, we are habituated to think of induction as a formal inference. This conception is highly influenced by the Humean tradition. In the Enquiry, Hume takes the inductive inference to be based on the transition from recurring observable correlations to the claim that two qualities are necessarily connected (E 4.16, SBN 32 − 4).Footnote 6 In the wake of Hume’s account, philosophers often take induction to consist of a generalization from observable correlations. We argue, however, that in contradistinction with traditional conceptions of induction,Footnote 7 Bacon’s inductive method cannot be articulated independently of his matter theory. The claim is that Bacon’s appetitive physics provides the basis for the inferential structure of his inductive method. Thus, Bacon’s induction is not devoid of theory; rather, it is grounded in it.

To support this claim, we first consider some general features of Baconian induction that indicate that his account is distinct from the formal account. In Sect. 2, we follow Bacon’s articulation of the inductive method, according to which the researcher’s task is to find the ‘form’ that is necessary and sufficient for the presence of each ‘simple nature’. We take it that by ‘simple nature’, Bacon refers to some elementary, sensory quality, which cannot be analysed further into other observable qualities. However, the notion of ‘form’ is shaped by a theoretical construct. Our preliminary aim in the paper is to demonstrate that the notion of form can be understood via Bacon’s appetitive physics. But the ultimate aim is to argue that this reading should imply a revision in our understanding of Baconian induction.

Our reading proposes that Bacon seeks parallels between two processes of becoming. First, there is the process, mostly observable, wherein a simple nature comes into being (e.g., the process by which the nature ‘heat’ becomes present in a body). Second, there is the mostly unobservable process by which bodies transform (e.g., realizing the inclinations for particles to move and for bodies to expand). The task of the inductive inference is to correlate the observable process with the one that is mostly unobservable. Once such correlation is found, Bacon’s conclusion would be that the observable process and underlying material process are one and the same. Thus, Bacon aims to reduce the observable process to a transformation introduced by some underlying physical process.

Induction, according to this reading, is an inference that takes us from the observable process by which individuals belonging to a natural kind come into being to the underlying hidden process responsible for the existence of natural kinds.Footnote 8 This hidden process is based on some universal principles of change or ‘laws of nature’. Bacon’s appetitive physics, we argue, is designed to conceptualize the broad outlines of hidden, material transformations.

To explain the relation between Bacon’s theory of matter and his method, we explore his earlier texts, where he articulates a new form of corpuscularianism. In Sect. 3, we reconstruct the textual evidence for the claim that Bacon adopts a particular type of corpuscularianism, made unique by his notion of appetites.Footnote 9 Moreover, we demonstrate the methodological implications of adopting such a theory of matter. Bacon imagines a science focused on unveiling laws governing a limited list of basic ‘motions’, from which one can construct all possible transformations of bodies. These basic motions can be either described as law-governed changes in corpuscular form, or as changes induced by the appetites present in corpuscles or composite bodies. The claim is that the two descriptions are complementary—law-governed transformations (i.e., motions) are simply the realization of processes induced by appetites, once the latter are freed from impediments and can materialize.

In Sect. 4, we revisit NO and argue that Bacon’s notion of form is best understood via his appetitive physics. These appetites are described via the laws that govern the process they introduce, once they are free to materialize. The notion of form has been associated in the literature with laws of nature, essential definitions, primary qualities, recipes for manipulating transformations, and limitations placed on the potentialities of matter. But all of these conceptual roles are better understood if one assimilates the notion of form to Bacon’s appetitive physics. In this section, we further claim that Bacon’s appetitive physics does not precede the inductive method, nor should it be understood as a hypothesis derived from or confirmed by observations. Rather, Bacon’s appetitive physics is essential to articulating his inductive inference. The upshot is that one should not understand Baconian induction as a formal inference, generalizing from particular observations to universal statements. Rather, one should view it as a method aimed at uncovering the underlying processes by which a certain observable nature comes into being. This inductive method is theoretical in nature, as Bacon applies his matter theory to conceptualize the various physical processes that underlie all possible changes in nature. A summary of this reading and some of its implications are presented in Sect. 5.

2 The Novum Organum and the Theory of Induction

Our first task is to articulate some broad features of Bacon’s inductive method. We argue that Bacon’s inductive procedure aims to uncover the process by which a natural kind comes to be. This account goes beyond merely describing the ‘natures’ associated with a natural kind. Bacon describes the method of induction as uncovering the ‘form’ that is necessary and sufficient for making a ‘simple nature’ present. The correlation between forms and simple natures is not the correlation between two observable qualities. The correlation Bacon seeks is that between an observable process (the coming to be of a simple nature) and another process (the law governing transformations described by forms). Thus, Bacon’s method of induction attempts to connect observable qualities with the hidden processes by which they become present.

In the NO, Bacon describes the method of induction as the search for correlations between ‘forms’ and ‘simple natures’. The purpose of building natural histories and conducting experiments is to discover, for each simple nature, the form that gives rise to it:

The work and aim of human power is to generate and superinduce a new nature or new natures on a given body. The work and aim of human knowledge is to discover (and the following are the terms which I possess that come closest to what I mean) the form, or the true difference, or natura naturans, or source from which a given nature arises. And to these primary works two secondary and lesser ones are subordinated: to the former the transformation, within the bounds of the possible, of concrete bodies from one into another; to the latter the discovery, in every case of generation and motion, of the latent process carried on from manifest efficient cause and manifest material cause all the way to the form implanted, and likewise the discovery of the latent schematism of bodies at rest and not in motion (NO, II, 1; emphasis in the original).

Note that Bacon emphasizes two different aims: human power and human knowledge. Both are related to a process of transformation. The aim of human power is to superinduce new natures, and to have the knowhow of transforming one concrete body into another. The aim of human knowledge is to discover the form of a given nature—or the source from which a given nature arises. The theoretical aspect of change consists of understanding the latent process out of which the nature comes to be. Bacon also mentions the latent structure which is the endpoint of the process.

Bacon thinks that there are two forms of inquiry, depending on the level of generality in which the inquiry is made. The fundamental level operates by analysing substances into “simple natures” (NO, II, 5). Bacon thinks that all substances, such as gold, can be analysed into their elementary, observable natures. He thinks that each distinct simple nature can then be studied independently, so as to discover the form that is correlated with its coming to be. Once such forms are known, one is able to induce these simple natures onto any substance. Inducing all the simple natures of gold onto a body essentially produces gold.Footnote 10

This first type of inquiry reveals the most fundamental level of knowledge. If one knows how to produce all simple natures of all substances, one ultimately knows how to produce all possible combinations of simple natures. Bacon’s understanding of natural kinds is anti-essentialist. Natural kinds are analysable into simple natures, and can be produced when one knows the process by which each simple nature is introduced. But Bacon thinks that alchemical transformations will only be possible when inquirers understand the forms of simple nature—i.e., when they understand the hidden processes by which simple natures come into being.

It is not always easy to analyse substances all the way down to their simple natures. When natures come together, they might not be separable in practice. Nevertheless, Bacon thinks that this is the final aim of scientific inquiry. When the origin of a simple nature is known, it is known in all generality. The implication is that if one understands the form that gives rise to the yellowish colour of gold, for example, one knows how to produce this colour in all substances. The form of a simple nature stems “from the things in nature which are constant, eternal, and catholic” (NO, II, 5). There is a universal theory of matter, underlying the entire variety of nature and division into natural kinds.

When the first type of inquiry is unavailable, given that it is not always possible to inquire after the forms of simple natures, a more modest inquiry can be made by studying the formation of concrete kinds of bodies. One can study how gold, which forms a composite entity, is formed as a unique concatenation of natures. This form of inquiry is not as fundamental or general as the first, but it may still be very useful for articulating ‘intermediary axioms’ or propositions describing processes that give rise to certain complex natures. For example, we may study the natural kind ‘animal’ by investigating the various processes by which animals are formed. This form of inquiry tries to understand the hidden processes by which animals are generated, without knowing the form of each simple nature of which animals are composed. To name another example, we may study how plants grow from seeds, are nourished, transform and become individuals of the ‘plant’ kind.

The intermediary axioms pertain to large groups of natural kinds (NO, II, 5). These secondary axioms are not ‘the general and fundamental laws which constitute forms’. Thus, Bacon describes both the ultimate and intermediary goals of inquiry: the ultimate goal of scientific inquiry is to discover the forms of simple natures, which are fundamental, universal laws. The subsidiary goal is to find general processes of change that govern large classes of bodies.Footnote 11

Note that Bacon thinks that knowledge of forms requires knowledge of latent structures and processes. Clearly, he thinks that forms are not directly observable by the senses.Footnote 12 This is in line with his many sceptical comments about the veridical nature of the senses (NO, I, 41 and 50).Footnote 13

Understanding Bacon’s logic of induction requires a proper interpretation of the notion of form, given that the goal of induction is to reveal the form that is necessary and sufficient for making a simple nature present. In the rest of the paper, we try to substantiate the following understanding of Bacon’s inductive method. Bacon’s inductive method works by first constructing a natural history of a simple nature. This requires carefully observing those cases in which a simple nature is present and those cases in which it is absent. Even more revealing would be cases in which various degrees of a simple nature can be observed. The next step is to find clues in the observable evidence of corpuscular tendencies (that is, appetites) that are responsible for making the simple nature present. This step involves generating a theoretical model for how a simple nature may come into being or made present. The theoretical model is constructed with the help of Bacon’s appetitive physics. However, the specific appetite conjectured is not determined by Bacon’s general theory of matter, but suggested by the empirical evidence itself. Thus, the researcher ought to conduct various experiments to show whether the specific appetites presupposed (and the specific transformations induced thereby) are necessary and sufficient for producing the simple nature. After a process of elimination, the researcher ought to isolate the relevant appetites. We argue that with the notion of ‘form’, Bacon refers to the appetites that belong to corpuscles, the specific ways in which appetites combine to produce transformations, and the corpuscular structures that allow for certain appetites to be expressed and for others to be suppressed.Footnote 14

3 Bacon’s Appetitive Physics

We use the Notion of ‘appetitive physics’, although in Bacon’s use of the term knowledge of appetites involves going beyond physics into metaphysics.

To establish the connection between Bacon’s notion of form, which is prominent in articulating his inductive method, and his appetitive physics, we would like to establish textual evidence connecting this notion to Bacon’s matter theory, developed in texts prior to the NO.

In Book II of NO, Bacon claims that to discover the forms of simple natures, one needs to uncover hidden processes and structures. In Book I, Bacon makes favourable remarks about Democritus’s atomism, although he does not endorse it unreservedly:

The human intellect’s very nature carries it towards things abstract and to fancying that things fleeting are fixed. But to abstract from nature is not as effective as to dissect it, as did the school of Democritus which penetrated further into nature than the others. We should rather focus on matter, its schematisms and metaschematisms, and the pure act and the law of that act or motion. For forms are fictions of the human soul, except when you want to call those laws governing the act forms (NO, I, 51).

Thus, this aphorism appears to place the notion of form in the vicinity of Democritean atomism, because Bacon speaks favourably of the school of Democritus, and then argues that one should focus on matter, its structures and processes. He also associates form with ‘the pure act and the law of that act or motion’.

While NO carries textual evidence that Bacon still holds a form of corpuscularianism to be valid, the full and explicit articulation of the program appears in texts written prior to it. Reading these texts suggests that while Bacon is inspired by Democritus’s atomism, he is interested in revising it. The most significant revision to corpuscularianism is the introduction of ‘appetites’ attached to atoms or corpuscles—active principles that induce transformations in bodies.

Bacon’s particular brand of appetitive physics is developed in several texts. The most elaborate articulation is in the Cogitatione de Natura Rerum (CNR, Bacon 2011).Footnote 16 There, he argues that “Democritus’s doctrine of the atoms is either true, or usefully applied to demonstrative reasoning” (CNR, 15). A little later he asserts that the contemporary sterility of philosophical discussions stems from lack of concern with atomist theory (CNR, 17). However, Bacon is also critical of Democritean atomism, as he attempts to transform ancient atomism into a scientific theory more suitable for the study of natural phenomena.

In CNR, Bacon considers specific theoretical issues concerning atomism. He argues that an atom is smaller than the smallest particle that is observable to the senses and that it is not infinitely divisible. We can infer these claims indirectly from observation (e.g., dissolving saffron powder in water, where the particles of the powder are not observable, but one still observes the change in the water’s colour; CNR, 16). Thus, the presence of atoms is still indirectly detected, even when they are mixed with other substances or spread throughout air.Footnote 17

One of Bacon’s revisions concerns the role of traditional atomic properties, such as size, shape, and mechanical forces, in explaining natural phenomena. He is interested in whether all atoms are the same, or whether one ought to think they have different sizes and shapes, as in Democritus’s theory. Bacon associates the previous option with Pythagoras, given that, if all atoms are alike, the number of atoms is in some way a representation of a body (CNR, 18). Thus, he thinks that atoms’ overall descriptions should determine whether they have distinct primitive natures.Footnote 18

Bacon is preoccupied with the evidence Democritus may provide for the variety of atomic parts. Some evidence may be derived from the fact that many transformations in nature are impossible. He argues that the variety of the parts does not follow from these natural prohibitions (CNR, 18). The upshot of these considerations is that Bacon indirectly argues for the uniform of nature of atoms. He is concerned with showing that the evidence does not conflict with this uniformity. Bacon’s focus suggests that he does not think that atomist theory has the potential to explain natural phenomena by appealing to the variety of atomic, primitive properties. All atoms are the same, and if there are active principles associated with atoms, these would be universally the same.

The most significant of Bacon’s revisions concerns the role of active principles in explaining natural phenomena. In CNR’s third meditation, Bacon considers the accepted views on possible changes in nature. He distinguishes between two ways of analysing change (CNR, 19). The standard way amounts to studying ‘resting principles’ by considering ‘from what a thing comes and is made up of’. The mode of inquiry that relies on resting principles considers the state a substance is in, what it is made of, and perhaps the state from which it was and is coming. The target of Bacon’s critique seems to be the Aristotelian account of change, according to which change amounts to a substance acquiring and making present a form, or making a present form absent. In contrast to a science that focuses on resting principles, Bacon offers to study nature according to its ‘moving principles’.

Bacon’s alternative mode of explanation articulates principles that describe the process by which the parts of bodies coalesce and expand. Knowledge is gained when one understands how bodies change their corpuscular configurations, not the particular configuration they have at a certain instant. Moreover, when a body possesses a certain nature, this nature is explained as an equilibrium between various dynamic processes (CNR, 25). What appears to be an instantaneous nature we attribute to a body is actually a kind of motion or transformation that the parts of the body undergo, or a kind of equilibrium introduced between various tendencies to change, together with a particular arrangement of corpuscular parts that leads to this equilibrium.Footnote 19

Bacon argues that traditional accounts of change are all “apparitions and appearances on the surface of things” (CNR, 20). He reviews various accounts of change, and claims all are illusory. He offers to replace them with an account that searches for the appetites and inclinations of bodies:

With these things dismissed, or related and damned to vulgar expositions, those inclinations and affections of things finally ought to be investigated, from which flow and emerge, as we see, such a great variety of effects and changes in the operations of both nature and craft. And this is to be done so as to bind nature, like Proteus in chains. Proteus’s true chains are the rightly discovered and discerned kinds of motions. For the conversion and transformation of matter itself follows the stimuli and constraints of motion (that is, of excitation and restraining) applied (CNR, 20–21).

This passage presents an alternative view of matter, but also an important methodological aspect that follows from this view. Bacon argues that inclinations and affections of things ought to be studied; that is, instead of considering the particular state in which a body is, or a property which it has, one ought to study the inclinations for change, that is, the dispositions of material substances to transform in particular ways. To explain his approach, Bacon uses Proteus as a metaphor for matter. Proteus can foretell the future (i.e., provide knowledge), but will only do so if captured. Proteus avoids capture by assuming different forms. Bacon claims that Proteus’s true chains (the state of being captured which will reveal Proteus’s knowledge) are the discovered kinds of motions—that is, the specific ways in which matter is transformed. One can study them by considering both the stimuli (i.e., inclinations that propel transformations) and the constraints of motion (i.e., the impediments that constrain the expression of inclinations for change). Thus, Bacon’s main point is that a new way of studying nature ought to be introduced. The study of change and transformation itself provides a fundamental means of understanding nature and revealing her secrets. The central theoretical and practical tool that will aid in studying these transformations is the concept of inclination—the tendency of bodies to transform in particular ways.

This above quote suggests a theoretical connection between the ontological basis for change (the inclinations and affections of things) and the effects and changes that ‘flow and emerge’ from them. Thus, there are inclinations in bodies, and then there are changes, or ‘motions’, that result from them, once these inclinations are free to materialize. Thus, there is a clear ontological connection in Bacon’s mind between the various changes or ‘motions’ that bodies undergo and the underlying inclinations that induce them.

Bacon argues that one will understand nature when one is able to discover and classify various kinds of motion:

Indeed, the principles, origins and forms of motion, that is, the strives and affections of matter of every kind, are lacking in philosophy. And subsequently also: impressions and impulses of motions, restrictions and obstinancies, paths and impasses, alternations and mixtures, periods and sequences and, finally, the universal progression of motions (CNR, 21–22).

Here, Bacon takes ‘principles, origins and forms of motion’ to be the strives and affections of matter. It is best to think of the expression ‘forms of motion’ as referring to forms of transformations induced by tendencies imprinted on matter. For example, if bodies are endowed with some inclination to contract, we can describe this inclination by attributing to bodies the appetite or tendency to attract other bodies. But this inclination can only be described by providing an account of how the distances between corpuscles change, once the inclination is free to materialize. Thus, Bacon sometimes describes inclinations by thinking about them as dispositional properties that bodies possess (i.e., appetites), but sometimes he describes them as ‘forms of motion’, that is, typical patterns of change. According to Bacon, all categories of change (including generation, decay, and alteration) are reducible to forms of motion. Thus, all material change should be reduced to some appetitive physics.

Given his atomist background and discussion of actual inclinations he thinks he has discovered, it is clear that for Bacon, forms of motion are described via tendencies to change the corpuscular configuration of a composite body. Thus, the tendencies are described via the principle or the law that governs changes of corpuscular configurations, once such a change is free to materialize.

According to Bacon, the aim of science is to identify a list of fundamental motions, from which all types of transformations are derived. Bacon here suggests that the large variety of motions might be reduced to very simple patterns—“a few natures of simple motions and origins” (CNR, 22). The standard atomist metaphor (comparing bodies and their parts to words and the letters from which they are composed) is transformed by Bacon to express an analysis as applied not to matter, but to the forms of motion, that is, to the typical ways in which bodies change the configuration of their corpuscular parts.Footnote 20

In section V of CNR, Bacon articulates ways in which the investigation of motions of bodily parts yields knowledge about the qualities of bodies. The section is intended as an initial investigation of ‘forms of motion’. For example, he considers why water in a vase with a perforated bottom does not pour out of the bottom. He claims that the water as a whole is still because the parts of the water experience both an inclination to move downwards and an inclination that pulls them upwards, given that nothing can enter the top of the vase if the water descends. Bacon observes that “if someone holds a weaker rival in a wrestle, such that he cannot move himself, and yet resist with vigor, yet it is not because the motion of resistance is smaller, but because it does not prevail and is subdued by a greater motion” (CNR, 25). Thus, we can understand a particular state of water as the equilibrium between two opposite inclinations. The same tendency downwards exists in parts of solid bodies, such as timber. But we do not observe this tendency, because the parts of timber strive to remain together: “The stronger motion is, certainly, the strive for continuity, or alternatively, the fleeing from separation” (CNR, 26).

In CNR, Bacon articulates a program for natural philosophy. One ought to find a list of basic forms of motion, and show how other processes and qualities are effects of those elementary forms. Bacon’s commitment to appetitive physics is also expressed in other texts, most notably Sapientia Veterum (SV, Bacon 1884) and De Principiis Atque Originibus (PAO, Bacon 1996, 195–270).Footnote 21 In these texts, he develops his interpretation of various ancient myths and weaves his corpuscularianism into his interpretations.Footnote 22 For example, Pan represents universal nature, which consists of an ‘infinite number of individuals’ which nevertheless form a finite number of species. Coelum represents the eternity of matter, which, as in Democritus’ theory, pre-exists the world. Proteus is interpreted by Bacon to be the underlying material processes that explain change (this recalls the claim in CNR about chaining Proteus). Cupid or Love is interpreted to be the atom.

In Cupid’s myth, Bacon interprets the Love associated with Cupid to consist of the appetites of primitive matter—in other words, the appetites are primitive properties of atoms or corpuscles. The emphasis in this interpretation of the myth is again, as in CNR, on principles of motion or the inclinations that lead to change. In the myth, Cupid is said to be an orphan, and Bacon interprets this as standing for the fundamental explanatory role of appetites. One cannot provide a cause for appetites as they are the bedrock of explanations for natural processes. Bacon associates the most fundamental appetites with laws imposed by God on atoms:

[T]he summary or collective law of nature, or the principle of love, impressed by God upon the original particles of all things, so as to make them attack each other and come together, by the repetition and multiplication whereof all the variety in the universe is produced, can scarce possibly find full admittance into the thoughts of men […] (SV, 368).

Thus, appetites are described in this myth as governed by laws of nature. In the myth, Cupid is described as having four attributes: eternal infancy, nakedness, blindness and archery. Eternal infancy is interpreted by Bacon as the invariable role of corpuscles, which do not grow or change, but remain the same. Nakedness is the lack of properties or essences in corpuscles, which is entirely different from the range of properties one finds in composite objects. Blindness refers to the lack of telos or purpose that characterizes corpuscular changes. Finally, archery refers to the virtue or power of the corpuscles that operates at a distance. Bacon seems to take this power of acting at a distance to be necessary for any motion. In short, we can see that SV essentially takes the program articulated in the CNR and reads it into ancient myths.Footnote 23

4 Form in NO as Related to Bacon’s Appetitive Physics

Bacon’s appetitive physics is developed over several texts. If we agree with Rossi and date PAO to the end of Bacon’s life, we may think of Bacon’s appetitive physics as stable throughout various phases of his thought, despite some changes in detail. In the reading provided here, the appetitive physics discussed in the earlier texts is also fundamental for understanding the inductive method, articulated in NO. To substantiate this claim, we argue that Bacon’s notion of form can identified with laws of transformation, which are induced by various inclinations and appetites that are present in corpuscles. What complicates the analysis is that the Baconian notion of form also involves the hidden ‘structures’ (schematisms), given that the form of an observed simple nature may be described as an outcome of a combination of various appetites. To describe such a combination, or to explain how an appetite is expressed and results in a particular motion requires accounting for the particular structure and contingent configuration of parts.Footnote 24 This interpretation can be substantiated by showing how close the NO notion of form is to the CNR account of ‘forms of motion’. In CNR, forms of motion are typical paths of transformation introduced by the appetites that are present in corpuscles. In NO, forms are hidden processes governed by laws. Our claim is that while in NO Bacon refers only obliquely to appetites, the notion of form in NO can be explained with the notion of ‘form of motion’ in CNR.Footnote 25

Given its semantic connotation, one might associate Bacon’s notion of form with the Platonic or Aristotelian notion. Larsen (1962), for example, thinks that Bacon’s work does not represent a break from the traditional, Aristotelian view of nature. However, Bacon’s notion of form clearly represents a new way of thinking about natural kinds.Footnote 26 The traditional notion of form represents the unique essence that belongs to a natural kind. In Aristotle’s account of the notion, gold has a unique substantial form that makes it the particular kind of thing it is. The essential form of gold is radically different from the essential form of silver, and each is responsible for the types of transformations that govern each natural kind. Bacon’s notion of form aims to uncover the universal processes of nature. It does not describe the process of transformation that governs a specific natural kind, but the specific circumstances that allow universal processes to produce natural kinds. Thus, Bacon’s theory describes how one can transform a body belonging to one natural kind into a body belonging to another.Footnote 27

The connection between Bacon’s notion of form and his appetitive physics can be gathered from the coherence between the corpuscularian program articulated in CNR, SV and PAO, and the various textual clues that Bacon leaves behind in NO. Admittedly, these clues are scattered throughout NO and have to be assembled carefully. The first important clue is the close association between the notion of form and laws of nature:

I have not forgotten what I noted and corrected above as an error of the human mind in denouncing the view that forms are primary essences. For although nothing really exists in nature besides individual bodies, carrying out pure, individual acts according to law, yet in the sphere of doctrine, this very law, and the investigation, discovery and explanation of it, is the very foundation of knowing as it is of operating. It is this law then, and its clauses, that I understand by the name of forms, especially as this term is current coin and crops up all the time (NO, II, 2).

Without bearing in mind his appetitive physics, it is somewhat difficult to understand the alternative Bacon proposes to the Aristotelian notion of form. Here, he claims that the notion of form is associated with the acts of individual bodies and the laws that govern them. He also thinks that discovering these laws is the purpose of scientific inquiry. Given the possibility of associating NO’s notion of form with CNR’s ‘forms of motion’, a natural interpretation suggests itself, according to which Bacon uses the notion of form to refer to the simple motions of CNR (or a combination of those simple motions). We have seen how the CNR takes the simple motions to be derived from appetites. Moreover, we know from SV and Cupid’s myth that Bacon thinks that these appetites belong to corpuscles and are governed by laws of nature. If we try to understand NO in relation to these earlier texts, it is natural to think that the laws to which he refers NO are the ones governing the simple motions introduced by the appetites of matter.Footnote 28

Another textual clue connecting appetitive physics and Bacon’s notions of form can be seen in the following aphorism:

In the same way, the investigation and discovery of the latent schematism in bodies is, no less than the discovery of latent process and form, something new […].

Thus we must make a separation and dissolution of bodies not by fire indeed but by reason and true Induction with experiments to reinforce them; and by comparing them with other bodies, and reducing them to simple natures and their forms, which in a compound body come together and become intertwined; and we must clearly move on from Vulcan to Minerva, if we mean to bring to light the true textures and Schematisms of bodies (from which all the hidden and (as they call them) specific properties and virtues in things depend; and from which too the rule governing all power alterations and transformations is derived).

But on these things, as well as in all discovery of latent schematism, a true and undimmed light is cast by the primary axioms, a light which banishes all obscurity and subtlety (NO, II, 7; emphasis in the original).

Bacon argues that one has to find the forms of simple natures, and these can only be found by moving from a blind, practical study of processes of change to one aided by theoretical and rational explanations. The transition is represented as one of moving from Vulcan (the patron saint of alchemy, according to Paracelsus) to Minerva (the goddess of wisdom). The true induction will be performed when ‘true textures’ are brought to light, which include both the latent schematism and the latent process. The reference to hidden textures suggests a corpuscularian background, while CNR, SV and PAO provide the type of corpuscularian theory endorsed by Bacon. Also, the recurring references to hidden process echo the CNR’s program of replacing ‘resting principles’ with ‘moving principles’.

Nevertheless, the notion of schematism requires more explanation. Given that Bacon thinks that analysis is reducible to hidden structures, recall that he thinks that research into forms might be performed at various levels of generality. At the most fundamental level, we find the universal appetites of matter, which introduce the universal, catholic principles. But if the analysis of matter is not performed all the way down to fundamental corpuscles, one may find a midlevel structure. It is useful to think of these structures as carrying their inclinations, so that one can uncover the role of these inclinations without knowing how to reduce them into the universal appetites of corpuscles. Thus, for example, it may be that all matter can be shown to have properties derivable from the properties of sulphur and mercury. The underlying schematism of bodies may include reference to these natural kinds, even though one may not have the ultimate, reductive account for them. This may be done when one analyses the formation of composite natural kinds, such as minerals, animal species, plant species, etc., in terms of inclinations introduced by this midlevel structure. But when one analyses the form of a simple nature, one needs to find the ultimate, universal appetites of matter that undergird it.

As argued shortly, simple natures are usually the result of a combination of various appetites. This is because the simple nature is static, and is therefore the result of an equilibrium or a struggle between various appetites. To estimate how an equilibrium results one must understand how the particular expression of an appetite depends on the context and on the contingent configuration of bodies. For example, in dense or rare bodies, the same appetites may have different manifestations. In different bodies with distinct corpuscular structures, the ‘struggle’ between various appetites may yield different results. Thus, in the case of understanding the form of a simple nature, the schematism may also refer to the corpuscular structure that is relevant for describing the form, given that this structure is relevant for understanding composite motions.

Given Bacon’s earlier form of appetitive physics, the association between forms and laws of nature, and the corpuscular language in describing what is necessary to inquiring what the forms are, there is reason to believe that Bacon takes his theory of appetites to undergird the notion of form. In our interpretation, Bacon’s notion of form refers to the appetites that introduce changes and transformations, or to the combination of appetites and particular corpuscular configurations that give rise to particular transformations.Footnote 29

4.1 Comparing our Interpretation to Other Accounts

How does our reading of Bacon’s notion of form fare compared to other readings? Bacon’s form is difficult to pin down because it serves several roles. But the interpretation introduced here can pull together distinct conceptual roles attributed to the notion. A misconception common in many interpretations is that they do not examine the notion via Bacon’s appetitive physics. More contemporary interpretations do so, but misconstrue the relation between form and simple nature because they do not consider it from a dynamic perspective. In our interpretation, Bacon’s inductive method attempts to establish the correlation between two processes—an observable process by which a simple nature comes into being, and an unobservable process governing corpuscular changes, induced by appetites. According to our interpretation, Bacon takes only the latter, unobservable processes, to be described by laws of nature. The overt process merely emanates from the underlying, unobservable process.

First, there is a common interpretive thread that links between Bacon’s form and laws of nature. These interpretations are often hazy about the character of the law, and do not interpret the notion of law via Bacon’s appetitive physics. Hesse (1964, 148) argues that forms correlate with laws of nature. She emphasizes the relation of these laws to a lawgiver, and thinks that knowledge of corpuscular arrangements (rather than inclinations for their changes) would reveal the laws. Horton (1973, 243–244) claims that forms mean nothing else than laws of nature. But she understands Bacon’s conception of natural law to be a law that connects the cause with the simple nature: “That is, the Form is not the essence, it is the statement or law concerning the relationship between the general source and the particular nature” (Horton 1973, 245).Footnote 30 If our interpretation is correct, the notion of law does not refer to the correlation between form and simple nature (which echoes Hume’s reading of laws) but with appetites present in corpuscles. The law that Bacon refers to is the law or the pattern by which a body changes its corpuscular arrangement. The simple nature is reduced to the law which describes the transformation in corpuscular arrangement. Thus, for example, on the one hand, a body can be described as hard. This is a simple, phenomenal nature that the body possesses. But then the body can also be described as having parts that have an inclination to expel other bodies from entering their inner bounds. The description which includes the form and involves the inclination is supposed to explain, and also replace, the description that includes the simple nature. In short, the law of nature does not involve the simple nature in its description, but is appealed to as a theoretical account of the process by which corpuscular structures change. These processes are correlated with the process by which an observable, simple nature comes into being.

Another interpretive strand connects the notion of form with a conceptual definition. Form is a necessary and sufficient condition for the presence of a simple nature, and so, when one discovers the form of a simple nature one can think of it as providing its definition. Jardine (1974) and McCaskey (2006; 2020) articulate such an interpretation. While there is something correct about the notion that a form defines the simple nature, commentators often do not realize that Bacon thinks of the relation between form and simple nature as a reductive one. Form ‘defines’ the simple nature not in the sense in which an explicit definition of one term shows how it is equivalent to others. Rather, it is a correlation between an observable nature and a theoretical description of how that simple nature comes to be. The definition is a ‘bridge’ between an observable nature and the underlying material transformation by which the observable nature becomes present.Footnote 31

Another interpretation assimilates forms and simple natures to the distinction between primary and secondary qualities. In Locke, for example, we find the distinction between the qualities one believes can be attributed to the bodies themselves, while the secondary qualities arise from primary qualities, together with the specific relation that the observed body has to the subject who perceives the body. This reading is present in Ellis’ introduction to Bacon’s works (2011, Vol. 1, 72), as well as in Ducasse (1951). This reading is correct insofar as one thinks that a simple nature is reducible to a form. It receives further support from Bacon’s account of the form of heat, where he argues that “the very heat itself or the Quid ipsum of heat is motion and nothing else” (NO, II, 20). Thus, Bacon clearly thinks that heat is reducible to the form of heat. Moreover, in analogy with Locke’s distinction between primary and secondary qualities, Bacon argues that heat, unlike the form of heat, involves a relation between the natural object being perceived and the perceiver:

As far as sense goes, heat is a respective thing, and relative to man, not to the universe; and it is rightly set down that heat is just its effect on the animal spirits. The effect is moreover intrinsically variable, since the same body can (according to the sense’s condition) induce the perception of heat or of cold—as is evident from Instance 41, Table 3. (NO, II, 20)

Thus, there is much that recommends Ellis’ and Ducasses’s reading that forms are primary qualities while simple natures are secondary qualities. However, their reading misses the significance of the type of theory which Bacon thinks is appropriate for describing primary qualities. Locke describes primary qualities as powers that are present in bodies that resemble the sensible qualities observed. Thus, one uncovers primary qualities such as size, hardness, number, and motion by showing that the primary qualities attributed to corpuscles are the same kind as those sensible qualities attributed to observable, composite bodies. For Bacon, the appetites present in corpuscular parts do not resemble observable qualities present in composite entities—they are not directly observable. One must perform particular experiments and induce changes in bodies before one can deduce the existence of these inclinations. Moreover, discovering appetites involves a complex process of generating models based on Bacon’s appetitive physics and testing whether they correlate with observable simple natures. To discover an inclination, one must conjecture that a certain inclination exists and then verify that it does lead to the presence of a simple nature. Moreover, these inclinations differ in kind from primary qualities one would intuitively attribute to atoms. By thinking about atoms, one might already attribute to them hardness, size, number and motion. However, attributing specific inclinations for changes to corpuscles requires thinking about the atom as a theoretical entity. The inclinations that explain natural phenomena are yet to be discovered. Thus, what is missing from Ellis’ and Ducasse’s account is the theory that Bacon utilizes to articulate the nature of primary qualities and the method for discovering them.

Another important interpretation of Bacon’s notion of form takes this notion to be non-theoretical. This interpretation takes Bacon’s form to be a practical recipe for inducing change. Bacon’s many comments about the need for science to produce works, and that truth is intimately connected to utility, recommend this interpretation. It is skilfully articulated by Perez-Ramos (1988; 1996),Footnote 32 who takes Bacon to be working within the Maker’s Knowledge tradition, where the knowledge of artisans and skilled workers takes preference over that of theoreticians. Form is not a theoretical description of the object being manipulated, but a set of instructions for manipulating objects to induce the transformations desired.

However, Bacon always emphasizes both practical knowhow and theoretical knowledge. There is never in his writing a preference of one over the other, since he believes the two are intimately intertwined (NO, I, 124). If we take Bacon’s notion of form to be explained by appetitive physics, we can understand how utility is wedded to truth. For Bacon, appetites and inclinations cannot be known from simple observations. First, inclinations of change involve changes of corpuscular configurations, which are mostly below the threshold of observable phenomena. Second, an inclination can only be known by letting it be expressed somehow. The impediments that obstruct the inclination from materializing should be removed, and one should observe whether the supposed natural paths of transformation come into existence. Thus, experiment and practical knowhow are essential for discovering corpuscular appetites, because natural paths of transformation are made possible via the practical knowhow of understanding and removing the relevant impediments. Moreover, the true test for discovering the form of a simple nature is to see whether one gains control over the experimental settings, so as to allow certain inclinations to become prominent, and then verify whether a simple nature becomes present. Without full control of the process of introducing a simple nature, there is always doubt whether one has understood the form that corresponds to it. For example, if hardness is truly associated with the inclination to expel other corpuscles, then the true test of this association is whether we can artificially produce the conditions that produce hardness. If we encounter a body that is not hard, we should be able to remove the impediments that render the repelling forces less prominent. Then, we should observe whether bodies actually become hard. Conversely, if hardness is present, we should be able to manipulate bodies so as to introduce the circumstances in which the natural inclination for making bodies impenetrable is overcome by other inclinations. The association between forces of impenetrability and hardness will be proven if hardness can be produced in every case scientists have induced the experimental setup in which the repelling forces are prominent.

Thus, utility and truth are closely wed in Bacon’s appetitive physics. A complete natural philosophy is one where all the forms of simple natures have been discovered. But the process of discovering the forms is intimately connected with experimental philosophy; it is impossible to discover forms without acquiring the practical knowhow of producing simple natures in natural objects. Thus, interpreters are correct in arguing that Bacon’s work involves a fundamental shift in the relation between theory and practice. But they are wrong if they hold that for Bacon, truth is defined solely in terms of utility, or if they take the method of discovery to be independent of utility.

Yet another interpretation of Bacon’s form was articulated more recently in Weeks (2007). According to Weeks, Bacon thinks of matter as carrying various potentials for transformation and unrealized states of matter. These potentialities for novel states of matter have been put in place by God during Creation. Weeks (2007, 249) identifies the knowledge of constant, eternal and catholic principles with the possibility of broadening human power over nature, that is, with natural magic. In Weeks’ interpretation, there are limitations that prevent new configurations from being put in place, and these are the forms. “Metaphysics considers nature from a cosmogonical perspective. It searches out primordial constraints that gave rise to this world. Hence, Bacon’s forms describe limitations on matter’s potency that resulted in the generation of simple natures (heat, light, death etc.)” (Weeks 2007, 225–226).

Our interpretation echoes Weeks in some respects, because she also identifies the ‘summary law of nature’ with Bacon’s appetitive physics. To discover the ultimate basis for the forms of simple natures one needs to inquire into the appetites for corpuscular change that exist in corpuscles. But Weeks thinks that the same laws could be considered from a ‘cosmogonical’ perspective. From this perspective, one can determine that “there is a fixed relationship between genus and species, a contraction or limitation of nature’s potency with a concomitant increase in generative power […]. The form is the law governing the act, the limitation or constraint of matter’s potency which we experience as a given simple nature” (Weeks 2007, 232).

According to Weeks, the cosmogonical perspective considers the process by which this particular world came into existence, producing along the way constraints on the way in which simple natures are generated. From the cosmogonical perspective, the forms are these constraints.

The passages that recommend Weeks’ reading suggest that Bacon thinks of forms of simple natures in terms of a genus that has some species that limits the range of individuals to which the genus applies. And it is in terms of this limitation that one can produce a simple nature. The problem with Weeks’ account is that the story she offers about the cosmogonical perspective on forms is rather murky. It is not clear how the limitations on the potency of matter ought to be described. Are they also to be described via appetitive physics? Does their content include reference to simple natures? Are the limiting forces, peculiar to certain species, additional forces, to be explored on their own? Are they to be described merely from the causal (or generative) perspective?

However, one can provide an account of limitations to species using the framework of appetitive physics, and provide a clearer account of why Bacon resorts to genus and species. Remember that Bacon urges us to transition from resting to moving principles. A state or a property that we attribute to a body, or a ‘nature’, results from inclinations for change that exist in the corpuscles from which the body is made. Thus, if there is a static nature that is attributed to a body, it must be the result of a struggle between two competing inclinations or the result of a particular inclination that is limited or restrained by particular configuration the corpuscles are in. Thus, Bacon thinks that the form of a simple nature is underwritten by a combination of inclinations, and that the nature also results from contingencies having to do with the corpuscular arrangement of particular bodies. Understanding the sort of limitations that give rise to static natures is also part of articulating the form of a simple nature. Thus, the cosmogonical perspective does not reveal new powers or forces that limit the potency of matter’s transformation, but merely reveals the particular circumstances and configurations in which the appetites for change yield static states or properties of matter, i.e., ‘natures’. So, against Weeks’ reading one can say that the cosmogonical perspective does not help articulate new limitations to a particular genus, but allows one to understand how a simple nature results from a conflict between two distinct universal inclinations for change.

The interpretive framework provided in this paper explains why Bacon’s notion of form has given rise to many different interpretations. Our suggestion is that identifying Bacon’s form with his appetitive physics explains all of above conceptual roles, while also explaining the ways in which common interpretations of Bacon’s works are unable to account for the overall coherence of his thinking.Footnote 33

4.2 Another Attempt at Induction

The interpretive stance we have endorsed in the previous two sections is that Bacon understands his notion of form in the framework of his appetitive physics. Bacon takes the notion of form to refer to the laws of nature that describe typical paths of transformation derived from appetites present in corpuscles. By employing experimental procedures that aim to allow the expression of constrained appetites, the inquirer attempts to find the correlation between observed processes of becoming (the making present of a simple nature) with mostly hidden processes driven by appetites and described by laws of nature.

Note that the inductive procedure may not reveal at first the fundamental appetites that are universal and exist in all corpuscles from which matter is made. By studying how concrete objects transform, one may be able to derive paths of transformation that pertain to a range of natural kinds, but not all matter. Appetites and inclinations might be studied at various levels of generality, so to speak. This provides an explanation for the oblique references to appetitive physics in NO, given that Bacon aims to demonstrate the utility of his method, without supposing that experimental inquiry would immediately yield the universal, catholic principles.

The guarded approach also implies that one ought to be careful before claiming to understand the nature of atoms (NO, II, 8). Bacon is not committed to a form of corpuscularianism where one has clear a priori knowledge of the corpuscular parts. Rather, one progresses towards the ideal of acquiring knowledge of universal principles by aiming increasingly towards knowledge of the way in which simple natures are produced. Thus, induction leads to various levels of generality depending on how close the appetites or inclinations discovered are to those present in the ultimate parts of matter.Footnote 34

According to our reading, appetitive physics is integral to Bacon’s inductive inference. Without positing some general theory of material transformation, one would not be able to make the inference from observable processes to mostly hidden ones. Prioritizing moving over resting principles requires a theoretical scaffolding for understanding material transformations. Thus, when interpreters think that Bacon’s theory of matter is speculative, conflicting with Bacon’s account of how induction works, they miss the very important connection between Bacon’s matter theory and how he thinks the inductive inference ought to be carried out. They overlook the intimate relation between theories of matter and methods of inquiry.

But how can one avoid thinking of Bacon’s appetitive physics as an idol of the theatre? Is Bacon not providing us with yet another hypothesis, one which can only be confirmed or refuted? Note that Bacon’s matter theory is merely a scaffolding. It tells us that the aim of the inductive inference is to find the appetites that give rise to those transformations that make present a simple nature. But the actual list of appetites can only be revealed via observations and experiments. The a priori theory of matter does not prejudge the results of inquiry because it cannot predict how forms would correlate with observed processes and which appetites lie at the basis of simple motions. Thus, we can liken Bacon’s appetitive physics to a fishing net. When fishermen go out to sea, they must use a net to capture fish. The net structure might determine the range of fish that will be captured—it may be that the net is unable to catch fish that are too small or too large. But whether fish are captured, or the kinds of fish that are captured, cannot be determined by the particular net used. Perhaps no fish will be captured, or the fish captured will be unlike any other fish captured before. Catching fish is an actual achievement that results from going into sea and casting the net. Similarly, Bacon’s matter theory can help reveal the appetites correlated with a particular simple nature, but the fact that it provides a scaffolding for inductive inference does not imply that it predetermines experimental results. Bacon’s appetitive physics is too schematic and too flexible to predetermine what actual observations and experiments might yield.

5 Conclusion

To understand Bacon’s account of inductive inference, we should avoid trying to fit his account into an Aristotelian or a Humean framework. Bacon’s inductive method is a reductive program, in which the inclinations for changes in the configuration of corpuscles are taken to be the basis for the process by which natures become present or absent. Observations and experiments guide the process by which particular species of motion (or ‘laws of action’)—particular dynamics of corpuscular changes—are deduced from experiments investigating the presence and absence of natures. Thus, while Bacon’s method stresses the significance of natural histories and experiments, the purpose of these empirical investigations is to provide context for the reductive program. Given that appetites can potentially come in a variety of types, only careful observation and experiment can determine the nature of these forms.

A misreading of Bacon’s method assimilates his ideas to Popperian falsificationism. According to this view, Baconian method is the practice of introducing certain forms, or hypotheses, to explain the presence of natures. However, there is only superficial similarity between Bacon’s method and falsificationism. The hypotheses introduced are not random conjectures, despite relying on some trial and error. The general structure of these hypotheses is given in advance and relies on a skeletal theory of how physical transformation and change is possible.

A vision of Bacon’s inductive method comes to the fore that is very different from our habitual understanding of induction. Bacon does not think of induction as a formal inference, one that takes given observation statements and generalizes from them to form theories about nature. Induction is a reductive program, based on a material theory of transformation. The purpose of experimental science is to investigate the transformation of natural objects and the coming to be of simple natures and natural kinds. The purpose of induction is to find a theory of matter that provides a unified account of how observable natures and natural kinds come to be. The outline of such a theory is given prior to the investigation, but the results of the investigation are determined only by observation and experiment. Which particular inclinations or appetites are associated with a simple nature can only be revealed by properly and methodically interacting with natural objects.