Francis Bacon

Bacon, Francis (1561–1626)

Along with Descartes, Bacon was the most original and most profound of the intellectual reformers of the sixteenth and seventeenth centuries. He had little respect for the work of his predecessors, which he saw as having been vitiated by a misplaced reverence for authority, and a consequent neglect of experience. Bacon’s dream was one of power over nature, based on experiment, embodied in appropriate institutions and used for the amelioration of human life; this could be achieved only if the rational speculations of philosophers were united with the craft-skills employed in the practical arts.

The route to success lay in a new method, one based not on deductive logic or mathematics, but on eliminative induction. This method would draw on data extracted from extensive and elaborately constructed natural histories. Unlike the old induction by simple enumeration of the logic textbooks, it would be able to make use of negative as well as positive instances, allowing conclusions to be established with certainty, and thus enabling a firm and lasting structure of knowledge to be built.

Bacon never completed his project, and even the account of the new method in the Novum Organum (1620) remained unfinished. His writings nevertheless had an immense influence on later seventeenth-century thinkers, above all in stimulating the belief that natural philosophy ought to be founded on a systematic programme of experiment. Perhaps his most enduring legacy, however, has been the modern concept of technology – the union of rational theory and empirical practice – and its application to human welfare.

1 Life

Francis Bacon was born into the political elite of Elizabethan England. His father, Nicholas, was Lord Keeper; his mother, Anne, sister-in-law to Lord Burghley, the Lord Treasurer. Much of Bacon’s career and even some aspects of his philosophy can best be understood as resulting from an upbringing which made him familiar with the exercise of power, and the wealth that came with it. His perspective is always that of an insider, but of one who experienced considerable difficulty in establishing his own position as such.

In 1573 Bacon was admitted to Trinity College, Cambridge. In later recollection at least, he found little to admire in the Aristotelian philosophy to which he was introduced, and still less in the writings of such authors as Peter Ramus, who were becoming fashionable alternatives (see Aristotle; Aristotelianism, Renaissance; Ramus, P. ). As was usual with undergraduates of his social rank, he did not take a degree. In 1576 he returned to London to train as a barrister at Gray’s Inn, an institution with which he was to maintain a much more enduring connection. His father died in 1579, leaving him with only a modest inheritance. Throughout his life Bacon spent freely and lived beyond his income; quite apart from considerable personal ambition, much of his pursuit of office can be seen as an attempt to repair chronic indebtedness.

Though he was elected to successive parliaments from 1581 onwards, Bacon’s career did not flourish under Queen Elizabeth, who recognized his abilities but seems to have found his personality unappealing. Burghley was more concerned to advance the career of his own son Robert, later Earl of Salisbury, and Bacon attached himself to Elizabeth’s last favourite, the brilliant but insubstantial Earl of Essex. Essex’s attempt in 1601 to restore his fortunes by staging an insurrection proved a complete fiasco, and made him liable to prosecution for treason. Bacon adroitly changed sides and prosecuted his former patron with a skill and vigour which provided ample confirmation both of his remarkable talents and of a fundamental coldness of character.

The accession of James I in 1603 presented the prospect – initially unfulfilled – of professional advancement. Bacon was knighted soon after the King’s arrival in London, but he had to wait until 1607 before being given his first important office, that of Solicitor General. It was only after the death of Salisbury in 1612 that promotion became truly rapid: in 1613 he was appointed Attorney General, in 1617 Lord Keeper, and in 1618 Lord Chancellor. This last office brought admission to the peerage, first as Baron Verulam (1618) and then as Viscount St Albans (1621).

Bacon’s fall was precipitous and catastrophic, though not entirely unpredictable. He had supplemented the income from his office by taking payments from those whose cases he heard, and though this was far from unprecedented it did make him vulnerable to attack. He was also important enough to be a substantial sacrifice to an angry House of Commons, without being so close to James that he could not be dispensed with. At the beginning of May 1621 Bacon was deprived of office, imprisoned – albeit for only a few days – in the Tower of London, fined £40,000, barred from court and prevented from taking his place in the House of Lords.

Despite his best efforts, Bacon never returned to favour. He spent his last five years in retirement, writing incessantly – at first with the hope of regaining office, or at least influence, and then merely to leave a testament to posterity. He died on Easter Day 1626, according to John Aubrey (who had the story from Hobbes) from a cold contracted after an experiment of stuffing a chicken with snow. As has often been remarked, it was a fitting end for so fervent an advocate of experimental science.

2 Works

During the first two decades of his adult life Bacon wrote little, or at least little that survives; it was however in this period that his outlook and basic ideas were formed – certainly by the early 1590s, and probably earlier still; in 1625 he mentioned to a correspondent that forty years earlier he had advocated the reform of learning in a work (now lost) entitled Temporis Partus Maximus (The Greatest Birth of Time) . The direction of Bacon’s interests is apparent in a letter of 1592, written to Lord Burghley, in which he (rather disingenuously) disclaimed any political ambition while simultaneously indicating the scope of his intellectual projects:

I confess that I have as vast contemplative ends, as I have moderate civil ends: for I have taken all knowledge to be my province; and if I could purge it of two sorts of rovers, whereof the one with frivolous disputations, confutations, and verbosities, the other with blind experiments and auricular traditions and impostures, hath committed so many spoils, I hope I should bring in industrious observations, grounded conclusions, and profitable inventions and discoveries; the best state of that province.

(1857–74 VIII: 109)

These themes, developed and articulated, were to preoccupy Bacon for the remainder of his life. No echo of them was however to appear in print for several years. Apart from some political tracts, the only one of Bacon’s writings to be published during Elizabeth’s reign was the first edition of the Essays (1597); the only portion of this volume of any philosophical significance is a short tract on ‘The Colours of Good and Evil’ , which provides early evidence of Bacon’s lifelong interest in fallacies and the pathology of the intellect.

The accession of James I stimulated a new burst of literary activity, of which the most visible result was The Advancement of Learning (1605), dedicated to the King and evidently written in the (unfulfilled) hope of munificent royal patronage. This was not the only project to have occupied Bacon’s attention during the first years of the new reign. A large number of fragmentary treatises have survived, some in English, some in Latin. Several have strange, enigmatic titles: Temporis Partus Masculus (The Masculine Birth of Time) , Valerius Terminus of the Interpretation of Nature with the Annotations of Hermes Stella, Filum Labyrinthi (The Thread of the Labyrinth) . Others are more prosaic: Redargutio Philosophiarum (The Refutation of Philosophies) , Cogitata et Visa de Interpretatione Naturae (Thoughts and Conclusions on the Interpretation of Nature ) . The diversity of the literary form displayed by these works is as striking as their unity of message: Bacon knew at least in outline what he wanted to say, but was undecided as to the most appropriate form in which to say it.

The last of these fragments probably dates from around 1608. For the next twelve years Bacon was increasingly busy with his official duties, and much of the time that remained was spent drafting and redrafting the Novum Organum. He did however find time to publish a second expanded edition of the Essays (1612) and one new work, De Sapientia Veterum (On the Wisdom of the Ancients) (1609), an interpretation of ancient myths as allegories of political and physical doctrine. The same pattern of thought can be found in the unpublished De Principiis atque Originibus (On Principles and Origins) (c.1610–12?), which also shows the considerable influence of Bernardino Telesio on Bacon’s physical doctrines, as do two other works written around 1612, Descriptio Globi Intellectualis (A Description of the Intellectual Globe) and Thema Coeli (Theory of the Heavens) , both left unfinished and unpublished.

The first instalment of Bacon’s chief work, the Instauratio Magna, was eventually published with appropriate magnificence in 1620, when Bacon was at the pinnacle of his success. The whole work was to contain six parts, but all that appeared at this stage were a general preface, an outline of the project as a whole (the Distributio Operis), an incomplete section of the second part (the Novum Organum), and a short Parasceve ad Historiam Naturalem et Experimentalem (Preparative towards a Natural and Experimental History) .

In the years that followed, Bacon went some way towards filling the lacunae in his original plan. The missing first part was supplied in 1623 by De Dignitate et Augmentis Scientarum, a revised and greatly extended translation of The Advancement of Learning. Despite its evident incompleteness, nothing more was added to the Novum Organum; most of Bacon’s efforts went into the natural histories intended to fill Part III, which he rather optimistically planned to produce at the rate of one per month. In the event only two were published before his death: on winds (Historia Ventorum 1622) and on life and death (Historia Vitae et Mortis 1623), although a work on the condensation and rarefaction of materials (Historia Densi et Rari) was also completed in 1623. Bacon’s executors ignored this – it eventually appeared in 1658 – but did publish the Sylva Sylvarum (1627), a natural history in English filled with some very dubious material, which proved very popular during the remainder of the century, but which provided much material for Bacon’s nineteenth-century detractors.

The final three parts of Instauratio Magna were never written apart from short prefaces to parts four and five (Works II: 687–92). The first of these, Ladder of the Intellect, was to contain actual examples of the new method in operation – something closer to perfection than the mere sketches provided in the Novum Organum. Part V, Forerunners, or Anticipations of the Second Philosophy, would, by contrast, exhibit discoveries made independently of the method, by the ordinary workings of the understanding. The content of the final part, the Second Philosophy or Active Science , can only be conjectured; one may suspect that Bacon himself had no very precise idea of what it would contain.

Perhaps the best picture of Bacon’s final vision can be found in a work of a very different kind, published in the volume containing the Sylva Sylvarum but of uncertain date. The New Atlantis is an account of an imaginary voyage to an island in the Pacific Ocean, and of the scientific institution, Salomon’s House, found there. Like most utopian narratives, this is deeply revealing of its author and provides the fullest picture we have of Bacon’s vision of a reformed, active science, and of the kind of institution that he saw as necessary to its flourishing. It also had a profound influence both on the millennialist, visionary Baconianism of the 1640s and on the founders and early practice of the Royal Society.

3 The division of learning

The Advancement of Learning contains two books, the first on the dignity of learning and the reasons for the discredit with which it was often regarded, the second and much longer on the classification of its various branches; in the 1623 translation this latter was expanded further, and divided into eight books.

The primary division of the branches of learning reflects the faculties of the human mind: history corresponds to memory, poetry to imagination, and philosophy to reason. Philosophy itself has three subdivisions: divine philosophy or natural theology, natural philosophy, and human philosophy, this last including the doctrine of the soul, logic, rhetoric, ethics and politics). Metaphysics is a branch of natural philosophy, concerned with formal and final causes, in contrast with physics which studies the material and the efficient. Metaphysics is a more general and more abstract discipline than physics, and rests on it, just as physics in turn rests on a foundation of natural history. The image is that of a pyramid whose vertex is the summary law of nature, known to God but perhaps beyond the bounds of human enquiry.

Rather unusually, Bacon made a distinction between metaphysics and philosophia prima – primitive or summary philosophy. The three main subdivisions of philosophy are not like lines meeting at a point, but like branches of a tree that join in a common stem. Arboreal metaphors of this kind may appear to suggest the Cartesian picture of science, in which the trunk of physics grows out of and is sustained by the roots of an a priori metaphysical system, but the reality is quite different. Bacon’s philosophia prima is a mere receptacle for such miscellaneous principles as have applications in several different disciplines – for example, that the force of an agent is increased by the reaction of a contrary, a rule with applications in both physics and politics.

Bacon’s most important innovation was, however, the close linking of theoretical and practical disciplines. In the Aristotelian tradition these had been kept quite separate, but now (within natural philosophy at least) each speculative discipline was to have its operative counterpart: corresponding to physics there would be mechanics; corresponding to metaphysics, natural magic. Bacon had no illusions about the pervasive fraudulence of the magical tradition, but – as in the parallel case of astrology – he sought reform, not abolition (see Alchemy ).

This close association of theory and practice was of the utmost importance: Bacon saw the dismal record of earlier natural philosophy as stemming very largely from their divorce. The practitioners of the applied arts had made what progress they had in a purely empirical way, unaided by any method, while the philosophers – especially, although not exclusively, the schoolmen in the universities – had disdained experience and, like spiders, had spun metaphysical cobwebs out of their own insides. The only hope of progress lay in uniting the two approaches.

4 The new logic

The Novum Organum has had far fewer readers than either the Essays or The Advancement of Learning , partly because of its more difficult subject matter, and partly because it was written in Latin; it is, however, Bacon’s most remarkable achievement, and the one which he himself regarded most highly. It cost him considerable trouble – William Rawley, his chaplain, described having seen no fewer than a dozen drafts revised year by year in the decade preceding publication. Bacon’s chosen form is the aphorism: initially these are short and highly compressed, but as the work proceeds they grow longer. In the second book, clearly less thoroughly revised, Bacon’s grip slackens and then loosens altogether, and the aphoristic form is abandoned except in appearance.

As its title makes plain, the Novum Organum was intended as an account of a new logic, designed to replace the Aristotelian syllogistic which Bacon saw as having hampered and indeed corrupted the investigation of nature. The full exposition of this is found in Book II; Book I contains a survey of the task and its difficulties.

The basic themes of the Novum Organum are set out in the first three aphorisms:

Man, being the servant and interpreter of nature, can only do and understand so much… as he has observed in fact or in thought of the order of nature: beyond this he neither knows anything nor can do anything.

Neither the naked hand nor the understanding left to itself can effect much. It is by instruments and helps that the work is done, which are as much wanted for the understanding as for the hand. And as the instruments of the hand either give motion or guide it, so the instruments of the mind supply either suggestions for the understanding or cautions.

Human knowledge and human power meet in one, for where the cause is not known the effect cannot be produced. Nature to be commanded must be obeyed; and that which in contemplation is as the cause is in operation as the rule.

(Bacon 1620: i.1–3)

Natural philosophy needs to begin with observation. Though Bacon sharply separated himself from those whom he classed as ‘empirics’, his objection to them lay in their lack of method and consequent recourse to unsystematic experimentation, not in their reliance on experience itself. Method is absolutely essential: unmethodical experimentation is mere groping in the dark, and is no more likely to produce results than digging for buried treasure on a purely random basis.

It is an essential feature of the new method that it can be openly described, explained and taught. The new reformed science is seen as an essentially collective activity; though undoubtedly presupposing a certain minimum of intelligence in its operatives, such an enterprise does not require, and is therefore not dependent on, the appearance of individual genius:

But the course I propose for the discovery of sciences is such as leaves but little to the acuteness and strength of wits, but places all wits and understandings nearly on a level. For as in the drawing of a straight line or perfect circle, much depends on the steadiness and practice of the hand, if it be done by aim of hand only, but with the aid of rule or compass, little or nothing; so it is exactly with my plan.

(Bacon 1620: i.61)

There is therefore nothing intuitionistic about Bacon’s approach, nothing at all resembling the Cartesian reliance on clear and distinct ideas. Bacon distrusted any appeal to the supposedly self-evident at the outset of any enquiry. Validation could only be retrospective: it was the ability of a theory to endow its holders with power over nature that provided the best, and indeed the only genuinely satisfactory, evidence for its truth.

Previous attempts at discovery had failed because men had either complacently supposed the mind already to be adequately equipped for the task, or else had despaired altogether. Nature is comprehensible, but its subtlety far exceeds that of the human mind. In order for anything to be achieved, a new logic based not on the anticipation but on the interpretation of nature needs to be brought into use.

This contrast between anticipation and interpretation is central to Bacon’s conception of his project. Anticipations are not hypotheses, but rather ‘the voluntary collections that the mind maketh of knowledge; which is every man’s reason’ ([c.1603] 1857– 74 III: 244). The root idea is one of superficiality: these are the notions of ‘folk physics’ – popular ordinary-language concepts such as arise in the ordinary conduct of life, sometimes refined and made more abstract by the labours of philosophers, but not fundamentally altered. ‘There is no stronger or truer reason why the philosophy we have is barren of effects than this, that it has caught at the subtlety of common [vulgarium] words and notions, and has not attempted to pursue or investigate the subtlety of nature’ ([c.1607] 1857–74 V: 421 ).

It was the all-pervasive unsoundness of the concepts used that made the old logic useless as a tool for the investigation of nature. Syllogisms incorporating confused and badly abstracted terms merely propagate error without supplying any means of correcting it; more generally, the teaching of deductive logic encourages the natural tendency of the mind to ascend hurriedly and without due examination to propositions of great generality, and then to regard these as securely established when investigating further. Bacon’s method requires not the liberation but the regulation of the intellect, which ‘must not… be supplied with wings, but rather hung with weights, to keep it from leaping and flying’ (1620: i.104 ).

Just as syllogisms are useless for any enquiry into nature, so too is the induction by simple enumeration described in logic textbooks. Bacon consistently regarded this with contempt – ‘childish’ was his favourite term of abuse. It operated on the surface of things, employing ‘popular’ notions, and was for that reason incapable of delivering certainty. Bacon was no fallibilist, prepared to settle for a natural philosophy of conjectures and merely provisional conclusions. Certainty was quite as important for him as it would be for Descartes, but what he was looking for was certainty of a very different kind – not immunity from sceptical doubt, but complete reliability. This could be furnished by induction, but it would have to be induction of a new and much more elaborate kind, one that could make use of negative as well as positive instances.

5 The idols of the mind

Before the new logic could be put to use, the weaknesses of the human mind which it was designed to correct or evade needed to be analysed. The central section of Book I is a counterpart to the analyses of sophistical reasoning provided in the logic textbooks. What emerged, however, was not merely a list of inductive fallacies, but rather one of the most memorable and original parts of Bacon’s system.

Bacon distinguished four classes of idols. The ‘Idols of the Tribe’ arise from the limitations of human nature; they can be allowed for and guarded against, but not removed entirely. Bacon had in mind such weaknesses as the tendency to suppose more regularity than actually exists, to be over-influenced by the imagination, and even more by hopes and desires. A very different kind of limitation arises from the dullness of the senses. Bacon had no sympathy with radical sceptical doubts of the kind that were to preoccupy Descartes, but he was acutely aware of the weakness of the human senses, and of their complete incapacity to discern the secret workings of nature. The problem was not one to be abandoned to sceptical despair or solved by metaphysical validation. Some assistance could be gained from the use of instruments, but the real solution lay in experimental design. Hidden processes would be linked with observable consequences, and an experimental determination of the latter would reveal the nature of the former.

The ‘Idols of the Cave’ arise from the idiosyncrasies of individuals, either natural or implanted by education. Some minds are good at seeing distant resemblances, others at making fine distinctions; some are attracted to ancient wisdom, or what might pass for it, others only to novelty; almost everyone is influenced by those disciplines which they know well, and even more by those to which they have contributed.

The ‘Idols of the Forum’ (or ‘Idols of the Market Place’) arise from the deficiencies of human speech. Bacon had no respect for the categories of ordinary language, or the habitual thought-patterns of the uneducated; ‘popular’ is in his lexicon almost invariably a term of disparagement. Words devised for the ordinary purposes of life cannot provide a satisfactory vocabulary for natural philosophy, and attempts to remedy the situation by making definitions achieve nothing: words are defined by other words, which themselves share the same defects.

These three classes of idols can be guarded against and to some extent allowed for, but never extirpated entirely. The fourth class is in this respect different. This consists of the ‘Idols of the Theatre’ – the point of the name was that rival philosophies were like stage-plays, with different casts and different plots, but all equally fictitious. The potential variety of such systems is clearly unlimited, but Bacon distinguished three main types. The natural philosophy of Aristotle and his followers was corrupted partly by logic, and partly by a reliance on common notions – popular conceptions quite unsuited to the task in hand. The empirical school (exemplified by the alchemists, but also including William Gilbert who investigated magnetism) was misled by too narrow a line of experimental enquiry: restricted ranges of data fill the imagination and lead to one-sided accounts of the world in chemical or magnetic terms. Platonism (Bacon had in mind not so much the doctrines of Plato himself – whom he generally treats with respect – as the Platonism of his own era) (see Platonism, Renaissance ) was worst affected of all, being corrupted by theology and superstition. Bacon’s own religious views are by no means easy to discern and have been very diversely interpreted, but one thing that is abundantly clear is that he was wholly opposed to the intrusion of religious doctrines, Christian or non-Christian, into natural philosophy; the result of allowing this to happen was a corruption of both, into a superstitious philosophy and a heretical religion.

6 Induction

Bacon’s methodological proposals occupy Book II of the Novum Organum. The first stage in any investigation is the gathering together of a natural and experimental history. This might be quite broad in scope – for example, the history of heat in aphorisms 11–18 – but it could be much more narrowly focused: Bacon’s own examples include histories of the rainbow, of honey and of wax. The idea of a natural history was an old one, going back through numerous Renaissance and medieval encyclopedias to Pliny, and ultimately to Aristotle’s Historia Animalium. Bacon, however, made an innovation of crucial importance. His histories would record not only material gathered from the ordinary workings of nature, but also novel phenomena generated by human activity. In the Aristotelian tradition such artefacts would have been discounted as inappropriate material for investigation; Bacon, however, saw them not merely as legitimate subjects of enquiry, but as especially valuable: ‘by the help and ministry of man a new face of bodies, another universe or theatre of things, comes into view’ (1857–74 IV: 253). Nature was to be put to the question – a contemporary euphemism for torture.

Histories of this kind could not be assembled quickly, and the whole project would clearly absorb a very large amount of labour and money. Bacon was acutely aware of this, but could see no alternative. The human understanding needed to be purged and cleansed, and this had to be done not by any Platonic (or Cartesian) detachment from the data of the senses, but by an immersion into the world of experience in its full individuality and variety. Bacon was a good nominalist in the English tradition: for him, individuals alone are real and our most reliable cognitions are our direct sensory awareness of them. Withdrawal to a world of abstract objects supposedly accessible to reason leads merely to illusion and the enunciation of empty generalities; for Bacon the word ‘abstract’ – like ‘popular’ – almost invariably carries negative connotations.

We have to begin, therefore, with particulars; we have also to begin with as full a range of particulars as possible. Bacon did not require all this data to be correct, though manifestly false material ought to be kept out where possible, and dubious reports marked as such. Some falsehoods were bound to creep in, but these could be dealt with; what could not be dealt with were biases which affected the whole history. Initial attempts to impose criteria of relevance had therefore to be outlawed altogether.

Most histories would contain an immense quantity of data – far too much for any individual human mind to grasp as a whole – and an ordering of this material into some kind of structure was essential. Bacon proposed the use of three tables: first a ‘Table of Essence and Presence’, listing all the situations in which the nature under investigation is present; then a ‘Table of Deviation or Absence in Proximity’, describing all those situations which are as close as possible to those in the first table but where the nature under investigation is absent; and finally a ‘Table of Degrees or Comparison’, a list of those situations where the nature in question varies in intensity, together with details of the circumstances accompanying that variation.

When first drawn up, the second and third tables would both, in general, be incomplete in that they would contain gaps corresponding to entries in the first. One of the chief functions of experiment was to remedy these defects: for example, given that the rays of the sun can be concentrated by a convex lens, a trial should be made to see whether such lenses can produce heat by focusing the rays of the moon, or any rays proceeding from heated stones or vessels containing boiling water.

When the tables have been drawn up it is possible to begin the inductive process itself:

The first work therefore of true induction…is the rejection or exclusion of the several natures which are not found in some instance when the given nature is present, or are found in some instance where the given nature is absent, or are found to increase in some instance where the given nature decreases, or to decrease where the given nature increases.

(1620: ii.16)

Only when this process of exclusion has been completed will it be possible to grasp the true essence (or form, to use Bacon’s own term) of the nature in question.

This method clearly rests on several presuppositions, of which the most fundamental is a principle of limited variety. Though the world as we experience it appears unendingly varied, all this complexity arises from the combination of a finite, and indeed quite small, number of simple natures. There is an alphabet of nature, which cannot be guessed or discovered by speculation, but which will start to be revealed once the correct investigatory procedures are employed. The time needed is indeed not merely finite but quite short: once the natural histories are complete, the unearthing of all the secrets of nature will require no more than a few years.

Bacon also assumed there to be a direct one-to-one correlation between natures and the forms from which they arise. He was aware that critics might deny this and maintain (for example) that the heat of the heavenly bodies and of fire, or the red in a rose and in a rainbow, are only apparently similar, having quite different causes in reality. Bacon firmly denied this – however apparently heterogeneous, these things agree in the forms or laws which govern heat and redness; indeed even such diverse modes of death as by drowning, by hanging and by stabbing agree in the form or law which governs death.

This way of thinking reinforces a tendency already present in the alchemical tradition of considering bodies as collections of simple natures, each explicable (and therefore reproducible) in isolation. Bacon certainly did think in this way: gold is yellow, heavy, ductile, fixed (that is, unaffected chemically by fire) and so on. Whoever knows the forms of these natures can attempt to join them together in a single body, and thereby transform that body into gold. At other times, however, Bacon seems to have recognized that forms are seldom independent: ‘since every body contains in itself many forms of natures united together in a concrete state, the result is that they severally crush, depress, break, and enthrall one another, and thus the individual forms are obscured’ (1620 : ii.24). They are not, however, hidden altogether: since expansion is part of the form of heat, all heated bodies must expand; but while the expansion of air is easily noticed, that of iron is less manifest to the senses.

The justification of the principles of limited variety and of the direct correlation of forms and natures could always be postponed; another problem, however, had to be faced at the outset. Exclusion involves the rejection of simple natures, ‘and if we do not yet possess sound and true notions of simple natures, how can the process of Exclusion be made accurate?’ (1620 : ii.19). The old logic had proved inadequate because of this deficiency; what grounds are there for supposing that the replacement would fare any better?

Bacon was acutely aware of this problem and of the difficulty it posed for his project. His solution was to propose a series of supports of induction: the account of these occupies the last part of Book II of the Novum Organum and is (characteristically) lengthy, elaborate and unfinished; indeed all he managed to describe was the first of his nine kinds of support, the ‘Prerogatives of Instances’, of which he distinguished no fewer than twenty-seven different varieties. Bacon’s account of these exhibits, perhaps more clearly than any other passage in his writings, the distinctive strengths and weaknesses of his mind. The discussion is often shrewd and sometimes much more – the instantia crucis has passed into modern science, under the name of a crucial experiment – but Bacon’s addiction to elaborate systems of classification and portentous schemes of nomenclature is frequently apparent, above all in the nineteen species of motion described in aphorism 48. The immensity of his intellectual distance from such contemporaries as Galileo is nowhere more apparent than it is here.

7 Natural philosophy

Bacon’s intellectual gifts were remarkable, but they were not those of a scientist. He was a lawyer, and it was here, as well as with human affairs in general, that his real area of expertise can be found. He was widely read in natural philosophy, but his approach remained that of an outsider, albeit a shrewd and exceedingly intelligent one. These limitations become particularly apparent when Bacon turned to astronomy, the most highly developed of all contemporary scientific disciplines. He rejected Copernicanism and, although he saw many of the weaknesses of the inherited astronomical tradition, unlike Kepler he had only vague and quite unhelpful ideas about how it might be reformed.

Bacon’s own physics was fundamentally non-mechanistic. Bodies contain two types of matter – tangible and spiritual – and the operation of the latter, although never explained clearly, is certainly not conceived in mechanistic terms. Bacon did, however, employ several ideas that were to be taken over by the mechanical philosophers who followed him, in particular that the observable qualities of bodies are to be explained by the constitution of their internal parts. Glass can be made white by being crushed into tiny fragments, and water white by being beaten into foam; heat is not a scholastic real quality but a kind of motion. Later Baconians such as Boyle and Hooke were able to take over these ideas and express them in more unambiguously mechanistic terms.

8 Bacon’s influence

Bacon’s philosophical writings met with little appreciation in England during the 1620s and 1630s. Admirers of the older learning, from James I downwards, were for the most part uncomprehending, and the one major scientist then practising, William Harvey, was brutally dismissive. Bacon had more impact in France, where he was carefully read by Mersenne, Gassendi and Descartes , but even they only responded to selected parts of the system, notably the ‘Idols’ and the appeal to experiment.

The political turmoil in Britain in the 1640s stimulated a new interest in Bacon’s thought, both among the advocates of universal reform like Samuel Hartlib, and among such natural philosophers as Robert Boyle and Robert Hooke. Baconianism indeed became the official philosophy of the Royal Society, celebrated in Thomas Sprat’s semi-official History (1667). The hopes thus stimulated, however, proved difficult to satisfy. Newton paid little attention to Bacon, and the Principia was an achievement utterly unlike anything projected in the Novum Organum. Locke’s debt was rather greater, especially in The Conduct of the Understanding , but by the early eighteenth century interest in Baconianism had started to decline.

Following the example of Voltaire, the French encyclopedists treated Bacon with great respect as an empirical, essentially secular thinker, to be contrasted favourably with Descartes who was now seen as scientifically discredited and too deferential to the Church. In Britain Bacon was ignored by Hume, but admired by Reid who helped create a widely influential methodological synthesis of Baconian and Newtonian ideas.

The Baconian revival reached its climax in the second quarter of the nineteenth century. Sir John Herschel’s Preliminary Discourse on the Study of Natural Philosophy (1830) was a thorough attempt to recast Baconianism in a form compatible with contemporary science. John Stuart Mill and William Whewell, though disagreeing about almost everything, both acknowledged a deep debt to Bacon, and to the inductive method of science. The most accessible introduction to early-Victorian attitudes towards Bacon is however provided by Macaulay’s essay ‘Lord Bacon’ (1837). Though respectful towards Bacon’s thought, Macaulay took a less favourable view of his character, and it was in response to his account that James Spedding undertook the labours that led to his Life and Letters (1857–74: vols VIII–XIV), and to the critical edition of Bacon’s works produced jointly with R.L. Ellis and D.D. Heath.

In the latter part of the nineteenth century, Bacon’s reputation as a methodologist began to decline. The trend continued after 1900, Bacon’s reputation reaching its nadir in the mid-century when Karl Popper proposed a method for science that eschewed induction altogether, and historians such as Alexandre Koyré offered accounts of the scientific revolution that made Bacon’s contribution utterly marginal. Since then there has been a modest revival, but Bacon has still not recovered an assured place in the philosophical canon.