Mary Shepherd's Refutation of Idealism By Jennifer McRobert Introduction Lady Mary Shepherd (1777-1847) was the second daughter of Neil Primrose, the third Earl of Rosebery, and the author of several philosophical treatises. During her lifetime, Shepherd wrote and published two major philosophical works: An Essay upon the Relation of Cause and Effect (1824) and Essays on the Perception of an External Universe and Other Subjects Connected (1827). 1 There are indications that Shepherd may also have written a third philosophical treatise, a teaser suggested in both the Dictionary of National Biography and a curious typewritten insert left in the Cambridge University copy of her 1827 publication. 2 Apart from this, very little is known about Shepherd's life and work, a fact that is surprising in light of her talent for clear thinking and the high calibre of her written work. 3 According to her daughter's memoirs, Whewell is reputed to have used one of Shepherd's books as a text at Cambridge, and Sir Charles Lyell said of her that she was an 'unanswerable logician, in whose argument it was impossible to find loophole or flaw.' 4 It is easy to explain our oversight of Shepherd's philosophy as part of a more general failure to document the contributions of women philosophers. However, in this instance, perpetuating the collective oversight would amount to the unwarranted omission of a significant scholarly contribution to the philosophical discussion and debate surrounding the work of Hume and Berkeley. What makes the loss of Shepherd's contribution especially poignant is not just that her work has scholarly merit, but that the obstacles to her writing and publishing her treatises would have been considerable. Standing in favour of her receiving some form of education would have been her aristocratic heritage and access to an already enviable collection of books in the family library at Barnbougle Castle. 5 However, in Shepherd's day, few Scottish girls received any education to speak of. Daughters of Scottish aristocrats would have been encouraged to restrict themselves to estate management and to acquire only the most basic of literacy skills. 6 Whatever the influences leading to Shepherd's development as a scholar, it seems reasonable to suppose that the late eighteenth century intellectual flourishing of Edinburgh society played an important role among them. In the latter half of the eighteenth century, numerous literary and intellectual societies sprang into existence in Edinburgh, including, among others, the Select Society, the Edinburgh Society, and the Pantheon Society. 7 With the leadership of local intellectuals such as Hume, Carlyle, Ferguson, Smith and others, these societies were much in demand. As Hume wrote to Alan Ramsey, founder of the Select Society, '...Young and old, noble and ignoble, witty and dull, all the world are ambitious of a place amongst us...' 8 That said, even a cursory look at Shepherd's writing is enough to establish that she was a rare breed indeed. Exceptionally well read and analytically clear, her style shows a marked preference for logic and a strong inclination to show up so called 'experts' by pointing to fallacies in their arguments. 9 It is in locating such fallacies and exposing them that Shepherd is led to elaborate her own philosophical views, which are, it turns out, quite unique and interesting. Since Shepherd's positive contributions are best understood in light of her critical responses to Hume and Berkeley, I shall reserve a fuller treatment of her epistemology and metaphysics for a later date, and restrict myself here to an analysis of Shepherd's critical responses to Hume and Berkeley. 10 The opening sections of the paper summarise first, Shepherd's logical analysis of Berkeley's arguments for sceptical idealism, and second, Shepherd's criticisms of Hume's account of causality. The third section begins by remarking upon Shepherd's failure to notice Berkeley's equivocation on 'causality', and notes that Shepherd herself invokes both a priori and a posteriori senses of causality in her arguments against Hume and Berkeley. The paper concludes with an assessment of Shepherd's responses to Hume and Berkeley in light of the role played by the a priori sense of causality in her arguments. Shepherd's Criticisms of Berkeley's Reasoning Shepherd often announces that it is her intention to critically assess Hume's account of causality, although much of what she writes aims directly against Berkeley's sceptical idealism. Her interest in the two philosophers converges on the problem of our knowledge of the external world. Evidently, Shepherd felt that an effective response to sceptical doubts about external existence would require an account of causality, since '...the question concerning the nature and reality of external existence can only receive a satisfactory answer, derived from a knowledge of the relation of Cause and Effect.' 11 Hence, in addition to her interest in causality, Shepherd sought to expose flaws in arguments for external world scepticism, and Berkeley's syllogisms were the subject of her careful examination. Indeed, logic and analysis were central preoccupations for Shepherd, who makes frequent references to Whateley's Logic and recommends that 'analytical philosophy' seek the 'scrutiny of the most rigid analysis.' 12 Consider Shepherd's criticisms of Berkeley's arguments leading to sceptical idealism, all of which involve the discovery of logical errors in his reasoning against our knowledge of an external world. Recall first that Berkeley argues for the principle 'esse es percipi', a principle which he thinks entails that no sensible object could have an existence distinct from its being perceived by the understanding. 13 Berkeley brings these ideas together to form his 'master argument', which can be reconstructed as follows: Sensible objects are things we perceive by the senses. Things perceived by the senses are nothing but our own ideas or sensations. Sensible objects are nothing but our own ideas or sensations. Sensible objects are nothing but our own ideas or sensations. Ideas and sensations could not exist unperceived. No sensible object could have an existence distinct from its being perceived by the understanding. Berkeley then invokes the likeness principle, which asserts that 'nothing can be like an idea except another idea'. Berkeley uses this principle to argue that any representation of a sensible thing, including that of an object, could only be like another idea: 14 Ideas and sensations are the only things we perceive. Objects are the things we perceive by the sense. Objects are only ideas and sensations. Thus far, Berkeley has attacked the representational account of nature. However, he has not yet taken the crucial step in defence of his own idealist position. He does this by offering a proof that spirits must be the cause of our ideas. Berkeley's main claim is that the causes of our ideas are spirits and that spirits are known by reasoning back from particular ideas to their causes. 15 He reasons that: Ideas are effects. All effects have causes. Ideas have causes. Ideas have causes. Causes are spirits. Ideas are caused by spirits. Mary Shepherd's strategy against Berkeley involves turning an etymological analysis of terms against his syllogisms. Berkeley's first argument, she points out, commits the fallacy of equivocation. Shepherd shows that Berkeley's master argument rests on an equivocal use of the term 'sensation'. When Berkeley says that ideas are imprinted on the senses he talks both in terms of our perceiving ideas through the senses and in terms of our having 'our own ideas and sensations'. These are, in fact, two different ways of talking about sensations. On the one hand, sensations are taken to be the cause of ideas namely, things that are independent of the mind; on the other hand sensations are taken to be nothing but ideas, namely, things that are dependent on the mind. 16 In using the term 'sensation' in the former sense, Berkeley suggests that ideas of sense cannot be imprinted until affected by outward objects. But this is to rely on a conception of the world that he explicitly rejects to describe his own view. Hence Berkeley's description of ideas being 'imprinted on the senses ... contains the very doctrine he is controverting.' 17 The second argument suffers from a similar flaw. Shepherd argues that there are four terms in this argument because Berkeley equivocates on the term 'perception'. Specifically, perception is taken to be mental consciousness of ideas arising through the action of organs of sense and mental consciousness of ideas of arising independently of the action of sense organs. The charge is that Berkeley cannot pretend that the 'objects of sense' are one and the same if they are conceived as existing both with and without the action of sense organs. 18 Shepherd's logical analyses of the first two of Berkeley's arguments are flawless. In fact, Berkeley's ambiguous usage of terms such as 'sensation', idea', and 'perception' are now standard criticisms. Shepherd's final criticism of Berkeley is that his third argument uses a term that he cannot, by his own light, claim to know. Berkeley's argument involves claims that all that exists are 'spirits' and 'ideas', and that spirits are the causes of ideas. In this case, Berkeley's analysis is problematic because he can have no idea of 'cause' at all; Indeed, Berkeley has already argued that 'ideas are not causes' and that he 'knows nothing but ideas'. So what sort of idea of cause could Berkeley possibly have? 19 While Berkeley is not charged with equivocation, he has erred in using a term that can have no exact meaning on his own theory of ideas. Shepherd's Critique of Hume on Causality In both of her treatises, Shepherd objects to the doctrine of causation in Hume, a doctrine whose arguments she regards as 'illogical' and whose conclusions she takes to be 'untrue'. 20 In her 1824 treatise, Shepherd summarises the claims to be demonstrated against Hume as follows: 1. That reason, not fancy and custom, leads us to the knowledge 'That everything which begins to exist must have a cause.' 2. That reason forces the mind to perceive that similar causes must necessarily produce similar effects. 3. I shall thence establish a more philosophical definition of the relation of Cause and Effect. 4. Show, in what respects Mr. Hume's definition is faulty. 5. Proceed to prove that Nature cannot be supposed to alter her Course without a contradiction in terms, and finally, show that Custom and Habit alone are not our guides; but chiefly reason, for the regulation of our expectations in ordinary life. 21 It is apparent from this list that the theme of Shepherd's earlier treatise is the nature of the causal relation, rather than the existence of an external world. The first proposition that Shepherd takes up in earnest is the claim 'That a being cannot begin its existence of itself'. This principle, she says, is demonstrable a priori, since it is impossible to conceive of causes and effects existing apart in nature without becoming involved in a contradiction. 22 The point rests on Shepherd's claims that 'Effects are no more than the new qualities of newly formed objects', and that these new qualities must necessarily be in the effects themselves 'in the very moment of their formation'. 23 Since new qualities are presumably brought about by causes, it follows analytically that 'it is impossible for causes and effects to exist apart in nature without becoming involved in a contradiction.' 24 This causal principle, she argues, counts against Hume's sceptical doubts about causality: If then (as I hope to have shown) all objects whatever, which begin to exist, must owe their existence to some cause, those we usually consider as effects cannot be held in suspense; suddenly alter their nature; be 'non-existent this minute, and existent the next;' and, though always introduced as qualities of other objects, be easily separated from the ideas of their causes, and require no 'productive principle'. 25 In addition, insofar as the principle counts against these sceptical doubts about causal regularity, the principle also leads to Shepherd's second proposition 'That reason forces the mind to perceive that similar causes must necessarily produce similar effects'. As Shepherd writes, 'the relation of cause and effect is the chief proposition immediately associated with and applicable to certain exhibited sensations. It can be used to infer that similar effects have similar causes, and that differences of effect are proportional to differences in causes.' 26 The first two of Shepherd's arguments appear to invoke an a priori causal principle. However, in proposing her more 'philosophical' definition of causality, Shepherd introduces a posteriori, non-logical elements in her account of causality and external existence: ...when the mind perceives by what passes within itself, that no quality, idea, or being whatever, can begin its own existence, it not only perceives the general necessity of a cause for every effect, but also deduces, that there must necessarily be a continually existing cause, for that constantly recurring effect, our perception of extension; or in other words, the existence of that which though unperceived and independent, merits the appellation of 'body.' 27 In the above passage, Shepherd maintains that causal necessity is discovered 'when the mind perceives what passes within itself'. Such an introspection of the mind's contents leads not only to the perception of 'the general necessity of a cause for every effect', but also to the perception of 'constantly recurring effects', which lead us to infer the existence of unknown, but continually existing causes. Perception of the mind's contents can lead to two kinds of inferences to necessary connection, Shepherd elaborates: First, there is the inference to the unperceived causes of particular sensible effects. Secondly, there is the inference to the necessary connection of invariable 'antecedency' and 'subsequency', which is associated with causal laws of nature. 28 Shepherd argues that Hume's doctrine is based on a faulty analysis of causation in terms of temporal 'antecendency' and 'subsequency' and on a mistaken analysis of causal objects. Shepherd claims that temporal contiguity is insufficient for causation, and that Hume is wrong to say that we form causal judgements merely by noticing the temporal order of sensible qualities. Shepherd's analysis turns on her claim that there is an important distinction to be drawn between the 'exterior object' that is the unperceived cause of sensible effects and the 'compound object' that results from a mental union of ideas. 29 While qualities of compound objects are perceived through the senses and mixed with ideas in the mind, the existence of unperceived, exterior objects is known by inference alone. Strictly speaking then, our ideas of causes are not perceived sensible qualities that precede our ideas of effects. Rather, we infer that unperceived exterior objects are causes of perceived qualities 'from the necessity there is, that there should be invariable sequences of effects, when one common cause (or exterior object) mixes successively with different organs of sense, or various parts of the human frame &c'. 30 Contra Hume then, sensible qualities give rise to ideas of invariable sequences of 'compound objects', which leads us to infer the existence of external causal objects: This impossibility of sensible qualities, being the productive principle of sensible qualities, lies at the root of all Mr. Hume's controversy concerning the manner of causation; for he, observing that such ideas could only follow one another, resolved causation into the observations of the customary antecedency and subsequency of sensible qualities. But objects, when spoken of and considered as causes, should always be considered as those masses of unknown qualities in nature, exterior to the organs of the sense, whose determination of sensible qualities to the sense forms one class of their effects; whereas philosophers, (with the exception of Berkeley) and mankind in general, look upon the masses of sensible qualities after determination to the senses as the causes, the antecedents, the productive principles of other masses of sensible qualities, which are their effects or subsequents; a notion naturally arising from the powerful style of the associations in the mind, and which our Maker has ordained for practical purposes; --but monstrous when held as an abstract truth in analytical science. 31 Thus, Shepherd has proven her last three propositions against Hume's view. She has established her more 'philosophical' notion of cause and effect, exposed flaws in Hume's reasoning, and argued that reason, rather than 'mere custom', is our chief guide in matters relating to cause and effect. In responding to Hume, Shepherd has also elaborated features of her own view of the causal relation. For example, it is clear from her arguments that Shepherd relies on both a priori and a posteriori senses of causality. On the one hand, Shepherd says that it is an axiom 'That no quality can begin its own existence,' 32 since the truth of this proposition is discovered by reason. On the other hand, although the proposition 'That every effect must have a cause' is demonstrable a priori, 33 Shepherd notes that we do not know what particular effect may arise as the result of a given cause. Hence, she also holds that perception leads us to the knowledge that the necessary connection of cause and effect '...arises from the obligation that like qualities should arise from the junction, separation, admixture, &c. of like aggregates of external qualities.' 34 In this second case, our knowledge of causality depends on an a posteriori sense of reasoning from effects to causes. Shepherd's Refutation of Idealism Thus far, I have shown how Shepherd employs the method of logical analysis available to her against Berkeley, and described Shepherd's response to Hume's reasoning on causality. Given her interest in both logical analysis and causation, it seems somewhat surprising that Shepherd fails to notice that in his third argument, the argument leading directly to sceptical idealism, Berkeley equivocates on the term 'cause'. Interestingly, the two senses of 'cause' invoked by Berkeley correspond to the a posteriori and a priori senses that we have just seen in Shepherd's response to Hume. It is hard to imagine that Shepherd missed Berkeley's latter equivocation, given that her first two attacks on Berkeley amount to charges of equivocation. Moreover, Shepherd was evidently well aware of these two distinct senses of causality, and also held that an analysis of causality would be central in defeating arguments for external world scepticism. So it is surprising, and even strange, that Shepherd does not apply these insights against Berkeley's third argument. Here is what such an analysis might look like: Berkeley's argument equivocates on the term 'causality', relying on both the a priori and a posteriori senses of reasoning from effects to causes in the same proof. In the first sense of reasoning from an effect to its cause Berkeley asks us to infer that our ideas have causes on the basis of the a priori causal principle that all effects must have causes. In the second sense, reasoning from an effect to its cause is based on an empirical sense of causal reasoning. That is, Berkeley asks us to reason from particular effects (our ideas) to their causes (spirits). In this instance, we are reasoning inductively from empirical phenomena (our ideas) to empirical causes (spirits). In the end, Shepherd's oversight is of little consequence for her critique of Berkeley. Shepherd has all along been aiming at the development of an even more substantive critique -one that rests on her considered view of causality. She announces at the start of her 1827 treatise that it is her intention to critically evaluate Hume's doctrine, and to apply the results of this investigation to the doctrine of Berkeley. 35 The former investigation yields the true 'philosophical' account of the nature of causality, which is required for proof of external existence. So, one explanation of why Shepherd overlooks the equivocation on causality in Berkeley's reasoning is that she has in mind an even more substantive critique of Berkeley involving causality. One of the first things that is clear in reading Shepherd's critique of Berkeley is that there is considerable common ground between them. They both subscribe, for example, to Locke's empiricist theory of ideas. As Berkeley writes in the Principles, '...the objects of human knowledge ... are either ideas actually imprinted on the senses, or else are such as are perceived by attending to the passions and operations of the mind, or lastly, ideas forged by help of memory and imagination.' 36 Shepherd offers a similar sensationist definition of the term 'idea'. I use the word idea, as signifying a distinct class of sensations, being the result of that reasoning or observation which shows that under certain conditions, there must needs be an existence when we cannot perceive it. In such is included the evidence for memory of the past; of such is compounded expectation of the future. Thus we have an idea of continual, unperceived, independent existence; -but only have a consciousness or sensation of dependant, interrupted, and perceived existence; whenever I have used it in any other sense, it is in a popular manner signifying notion or object of thought, &c. 37 Moreover, Shepherd also agrees with Berkeley's 'likeness principle', and his view that 'outward objects' cannot be ideas and sensations. The ideas of colours cannot be imprinted on the eye; nor those of sound on the ear; not those of extension on the touch; there are no such ideas, until after the eye, as an instrument, has been affected by some sorts of outward objects, fitted to convey to the sentient principle, a sensation of colour, and so of the rest. Therefore, the objects perceived by the organs of sense cannot be our ideas, and sensations. 38 However, Shepherd maintains that Berkeley's indiscriminate use of the term 'idea' to mean sensible qualities 'which arise from the organs of sense, in relation to external beings' and 'conclusions of the understanding' 39 betrays a confusion regarding the nature of objects. An object is not a mere counterpart to an idea or sensation, but a compound thing, which is the product of both sensations and reasoning. Shepherd writes that it is the union of three things that leads to 'the creation and production of all sensible complex qualities called objects': The union of the three following things are required to form the proximate cause for that great effect, the formation and combination of those aggregates of sensible qualities usually called objects; namely, first, the unkown, unnamed circumstances in nature, which are unperceived by the senses; secondly, the organs of the sense, whose qualities mix with these; and thirdly, the living, conscious powers necessary to sensation in general. 40 Most importantly, sensible objects are complexes that combine raw sense data and the causal principle itself: ...in every object of sense which the mind perceives, the knowledge of its genus, as a general effect arising from a general cause independent of mind, is mixed with the sensations or ideas resulting from its special qualities affecting the same. 41 So although Shepherd's account of knowledge is sensationist, her emphasis on the role of reasoning and inference in our knowledge of the external world takes her epistemology well beyond either naive empiricism or sceptical idealism. In the following passage, Shepherd emphasises that belief in the existence of external objects requires that 'quick suggestions of the understanding' be combined with sensible qualities: But then he [Berkeley] has omitted the consideration of that circumstance, which is necessary to our belief in the existence of objects independent of ourselves; and that is the quick suggestions of the understanding; the reasoning, that as sensation does not itself form the essence of those existences which cause particular kinds of sensations; therefore there must be existences without it; that sensation not causing the variety of its own perceptions, therefore there must be variety without it; that various existences must be ready in order to be perceived, and that these must lie under various positions in relation to each other, as well as to the mind; that sensation is but a thin gauze, through which things are seen in their native proportions, although it imparts to them a similarity of colouring. 42 Shepherd's response to Berkeley culminates in a refutation of idealism in which she appeals to something akin to Kant's phenomena/noumena and appearance/reality distinctions. With respect to the former metaphysical distinction, Shepherd writes that the 'assurance of other existences besides ourselves' follows from the inference that 'in order to support the phenomena, there must needs be other continuous existences than ourselves.' 43 Like Kant, Shepherd holds that perceived things must be supported by the existence of unperceived things. Shepherd's epistemology also invokes the epistemological appearance/ reality distinction. In this case, Shepherd claims that inferred marks of objectivity, such as our noticing 'the regular reply of the organs of the senses to the irregular calls made upon them' lead us to infer the existence of 'essences different from the mind': ...for the mind perceiving, upon each irregular application to some sorts of beings, or qualities, or ideas, which it may call the organs of sense if it please, that they regularly reply to that application, justly concludes them to exist when unnoticed, in order to be capable of this readiness to reply. Those objects, also, which do thus reply, yield to the sense of motion from point to point, an idea of resistance and extension in particular; and so are regarded as body; that is, as essences different from the mind, or the powers of sensation in general; but continually existing objects, or qualities, which yield ideas of extension, are not ideas, but continued existences called bodies. 44 Hence Shepherd's epistemology attempts a more sophisticated defense of knowledge of external things than representational realism. Shepherd's suggestion is that the senses lead us to discover objective features of external existence such as resistance and extension. Shepherd's view is that only the 'proportional varieties of external objects may be known', but that the 'real essences of mind and matter are unknown to us'. 45 In another passage, Shepherd indicates that qualities such as 'variety', 'independency' and 'existence' 46 are inferred 'exterior qualities' that we know resemble 'inward qualities': Variety (we know that like causes have like effects and also that differences in qualities have proportionally different causes), independency (we perceive that the general sensation of consciousness is independent of a given particular one) and existence (the existence of sensation is perceived in the very exhibition and conscious feeling of that quality) are the set of exterior qualities which we may know of as resembling such as are inward. 47 Thus, Shepherd would agree with Berkeley's assessment that the representational realist's appeal to psychological inclination is alone insufficient to establish existence or knowledge of external objects. It is through reasoning that the subject discovers sequences in phenomena, forms ideas of relations and external objects, distinguishes causality from the perception of mere succession, and ultimately, realises that she bears a relation to an external world: In short, the sensible qualities form the sensible objects; but it is a reasoning arising out of a perception of the relation of these qualities; -of the different positions of colours in relation to motion; -of the knowledge of the place where we are &c. by which external continuous existences are proved... 48 Unlike Berkeley then, Shepherd emphasises that inferential steps and epistemological criteria can lead us to postulate the existence of exterior objects and objectively real qualities, both of which derive from a world independent of the subject. Hence, the fact that our various sense perceptions converge on a single coherent account of the world is ultimately explained with reference to the marks of objectivity in knowledge. 49 It is interesting to note that Shepherd's reply to Berkeley is Kantian in several respects. First, it makes a Kantian appeal to a noumena/phenoma distinction. Secondly, it relies on an appearance/reality distinction. Thirdly, it suggests that epistemic criteria can be used to distinguish purely subjective states from objective reality. What Shepherd maintains is that the processes of abstracting from our selfconscious awareness of things leads us to infer that something external to ourselves exists. Shepherd concludes that 'The independence of objects of the sense from the general capacity for sensation (consciousness) is proved by the changes of qualities visited upon and appearing before the mind without our conscious awareness.' 50 In the end, Shepherd offers a more sophisticated response to Berkeley than most of her predecessors, and this is due, in part, to her recognition that an analysis of causality should figure in a reply to Berkeley. 51 Indeed, the early reception of Berkeley's philosophy could well be summed up by Ronald Knox's caricature of Berkeley's position in the famous limerick: There was a young man who said, 'God Must think it exceedingly odd If he finds that this tree Continues to be When there's no one about in the Quad.' REPLY Dear Sir: Your astonishment's odd; I am always about in the Quad, And that's why the tree Will continue to be, Since observed by Yours faithfully, God. 52 As Harry Bracken remarks, most of Berkeley's early critics merely sought to ridicule him, so that by the mid-eighteenth century 'Berkeley already has a reputation – he has already been called a sceptic, atheist, idealist, egomist and fool.' As a result, Bracken notes, we 'no longer need to suppose that the limerick Berkeley was the simple product of a straightforward reading of the Principles, -it was also the product of a bias engendered by the early critics.' 53 Not only was the ridiculing of Berkeley's position unattractive in its own right, but the early critics relied on fairly crude arguments to show that his philosophy led to absurdity. An early review in the Journal Litéraire, Perry and Baxter all charge that Berkeley begs the question against materialism. 54 Baxter also charges that in rejecting materialism Berkeley rejects the very possibility of science. 55 Samuel Johnson made the notorious remark 'I refute Berkeley thus' and then kicked a rock. Although there is much more substance than this to the early reception of Berkeley, Bracken makes a convincing case to show that Berkeley's early critics typically failed to address the crux of the issue. Where Berkeley's sceptical idealism is concerned, as Shepherd correctly perceived, it is the underlying account of causality and its connection to sensible objects that must be probed. Thomas Reid, for example, felt that Hume's critique of Berkeley on abstract ideas had already 'wantonly sapped the foundation' of Berkeley's view by undermining his case for immaterialism. 56 Although Shepherd is undoubtedly deeply influenced by the Scottish reception of Berkeley, 57 she rejects Reid's direct realism and, in particular, his view that it is possible to have immediate sensible knowledge of primary qualities, so she would have been satisfied with neither Hume nor Reid's assessment of Berkeley. However, it would appear that she takes quite seriously the sort of remark made by the French Encyclopedist Turgot, who urged that an adequate account of causality would be necessary to rebut Berkeley. 58 It is Shepherd's intent to provide just such an account. In sum, Shepherd offers a much more convincing argument than did her predecessors when she shows that the marks of objectivity in our knowledge lead us to infer knowledge causality and knowledge of 'exterior objects'. Indeed her rejection of Berkeley turns on a Kantian analysis that many other critics of empiricist scepticism were missing in their responses to Berkeley and Hume, but that Shepherd was clever enough to see would do the job. Causality in Shepherd's Refutation of Idealism Shepherd's refutation of idealism appears to turn on the 'philosophical' or a posteriori sense of causality that she develops as part of her critique of Hume. Indeed, Shepherd builds an argument for external existence around this a posteriori sense of causality in such a manner as to give us compelling reasons to reject Berkeley's idealism, and none of those arguments seem to depend on the a priori sense of causality. It is somewhat surprising then, when she claims at one point that her argument for the independence of external things itself depends on the axiom 'that no idea, or quality, can begin its own existence: The foundation for the whole argument relating to the independency of the sense organs is in the axiom 'that no idea, or quality, can begin its own existence. For we perceive that the sensation as of the use of any organ of sense, does not alter the mind always in the same way; therefore, the mind and the organs of sense being the same upon any occasion as on a former one, when no other object than themselves were present, a third object is required to occasion the interruption of its present state, which object is to be seen, or heard, or felt &c. 59 In addition to this remark, we have already seen that Shepherd's argument against Hume clearly invokes the same a priori axiom. As Hume (and later Kant) showed, the principle that 'All effects have causes' cannot be used to justify the inference that 'All events have causes'. 60 However, this is the very inference that Shepherd appears to make when she claims that to deny her causal axiom would lead to contradiction and 'That reason, not fancy and custom, leads us to the knowledge 'That everything which begins to exist must have a cause.' 61 The question is raised then: To what extent are Shepherd's responses to first Hume, and then Berkeley, compromised by her dependence upon this a priori sense of causality? The answer, I think, rests on the success of a unique strategy Shepherd employs to evade Hume's critique. The strategy involves linking her a posteriori and a priori senses of causality, so that ultimately, Shepherd's critical responses depend on the cogency of her linking argument. Consider first that Hume arrives at his constant-conjunction theory of causality by ruling out two alternative accounts: One account is that our idea of a necessary connection between causes and their effects arises from a logical sense of causal connection. The other account is that our idea of a necessary connection between causes and their effects arises from a nonlogical sense of a necessary connection between the same. The first alternative Hume denies, for reasons similar to those just given above. Specifically, Hume reasons that effects cannot be deduced from causes prior to experience such that we can know that one kind of cause is invariably linked with one kind of effect. But Hume also denied the plausibility of the second alternative, concluding instead that it is a subjective fiction of the mind that leads humans to ascribe causal necessity to nature. Hume's argument against the second alternative amounts to the claim that when he inspects his mental experiences, he finds that neither perception nor acts of will contain any element of necessity. 62 The claim that neither perception nor acts of will contain any element of necessity is, of course, the very claim that Kant denied when he maintained that the faculty of understanding supplies an a priori rule for our causal judgements. Kant's argument is based on the claim that we can distinguish between cases where we perceive the mere temporal succession in appearances and cases where we perceive an objective order in the succession of appearances. The very fact that we are able to make the sort of determination that leads to a causal judgement, Kant argues, should lead us to infer the existence of an a priori causal principle at work in understanding. Shepherd's argument resembles Kant's own rejection of Hume insofar as she argues that '...when the mind perceives by what passes within itself, that no quality, idea, or being whatever, can begin its own existence, it...perceives the general necessity of a cause for every effect.' 63 That is, Shepherd maintains that upon inspecting the contents of our perceptions, we do discover an element of necessity leading to an objective account of causal knowledge. First, she notes, there is the inherent orderliness in sense perception. Thus in a 'waking and sane state of mind', 'the harmony of ideas' and 'their relations and conclusions' is a sign that marks the difference between the order due to sense perceptions and 'dreams and frenzies'. 64 In addition to this, the mind takes notice of 'like qualities' arising from the junction, separation, and admixture of 'like aggregates of external qualities' and also of 'invariable sequences of effects'. In such cases, it is the invariability of the sequences that leads us to infer the existence of a necessary connection. 65 For this reason, Shepherd reproaches Hume on the grounds that 'Hume denied that 'reason could prove, by the relation of our ideas, the knowledge of continued existences, and resolved all into 'custom and imagination.'' 66 So Shepherd's case against Hume's constant-conjunction theory resembles Kant in at least this respect: Shepherd claims that in an empirical, non-logical, perceptual act of introspection, the mind encounters an element of necessity -the necessity of the a priori principle of causality. Like Kant, Shepherd's response to Hume involves rejecting the original form of Hume's dilemma between logical and non-logical necessity by maintaining that a non-logical element containing necessity is discovered in perception. If Shepherd is right, then the a priori sense of causal necessity is known to be true by demonstration, but its existence is also known through a non-logical act of perception. Clearly, the force of Shepherd's response to Hume lies here, in the additional non-logical evidence that the a posteriori argument supplies for the existence of the priori causal principle. It is apparent from what has been said above that Shepherd's response to Hume rests on her linking of a posteriori and a priori senses of causal necessity. But it is equally apparent that Shepherd assumes this same linkage in her refutation of idealism. Indeed, postulating such an assumption helps to explain why Shepherd's mention of the axiom 'that no idea, or quality, can begin its own existence' in connection with the 'independency' argument leads her directly to a justification that brings to bear the evidence of our perception. For what follows directly after Shepherd's mention of the axiom is her a posteriori account of the discovery of causes among the contents of our perceptions. Shepherd explains that 'we perceive that the sensation as of the use of any organ of sense, does not alter the mind always in the same way' and this leads us to infer the existence of some third thing, in addition to the mind and the organs of sense. This is hardly the sort of support one would expect for a principle whose sole justification was logical. The assumption that Shepherd intends to provide additional a posteriori evidence in support for the existence of the a priori causal principle also helps us to see the consistency between claims that she makes. For example, she asserts that the causal axiom is the foundation for her 'independency', but also that we know of the existence of external things when we 'perceive certain motions, changes, combinations of ideas'. 67 It is only on the assumption that Shepherd's argument for causality resembles the Kantian argument that we can make sense of her views. Finally, I think that it is because Shepherd a priori sense of causality is linked to the a posteriori sense of causality that her arguments provide substantive responses to Hume's subjectivism and Berkeley's idealism. Given that Shepherd does adopt a Kantian line of reasoning in her response to Hume, one is led to wonder why she does not follow his argument more closely in her refutation of Berkeley. Kant rests his own argument against Berkeley on the demonstration that objects of experience must be given to us in space and time, so that the foundation for his refutation of idealism lies in the arguments for space and time in the Transcendental Aesthetic. Although Shepherd does discuss the nature of space and time in her treatises, she virtually ignores them in her response to Berkeley. The reason for this is very likely that she rejects Kant's views of space and time. Shepherd writes that 'Kant imagines time and space to be only modes of the mind, which is mistaking the cause which determine a mode of the mind with the effect, viz. the mode of the mind.' 68 What Shepherd maintains that 'the notion of time is an idea the result of reasoning; but time itself is a capacity in nature fitted to the continuance of existence.' 69 Hence, although Shepherd may draw inspiration from Kant in her responses to Hume and Berkeley, it is also apparent that she develops a unique and original metaphysics and epistemology. Conclusion In conclusion, Lady Mary Shepherd's work offers a critical and original response to Hume and Berkeley that deserves the careful consideration of contemporary historians and philosophers. She is, in my estimation, the clearest and the most critically acute of the women philosophers of the modern period, with a distinctive, analytical style of criticism. She focuses her attention on careful definition and on the identification of fallacies in the arguments of her predecessors, and lays out compelling arguments against her opponents. In addition to identifying the conceptual and logical limitations of other philosophical arguments, she seeks to develop an original and plausible account of objective knowledge of the external world. This account might best be characterized as sensationist empiricism, since it emphasizes the role of the sense organs and sensation in knowledge acquisition. However, much of Shepherd's efforts are directed against scepticism, and one of her central concerns is to show that sensation leads to objective knowledge rather than to sceptical forms of subjectivism and idealism. Hence it is through reflection on the actions of sense organs that we come to infer the existence of bodies and real characteristics of bodies such as resistance and extension. Although sensation and sense organs play an important role in our coming to have beliefs about external things, our belief in an external world of unperceived things, such as causal objects, is in large part a product of reasoning. Shepherd's aim then, is to show that a modified form of empiricism, a view that differs from both Berkeley and Hume insofar as it defends the objectivity of our knowledge of external world, conforms to 'our common everyday experience,' refutes idealism and avoids scepticism. Thus, Shepherd's responses to Hume, Berkeley, and others lead to a subtle and complex account of our knowledge of the external world. 1 Mary Shepherd. An Essay upon the Relation of Cause and Effect Controverting the Doctrine of Mr. Hume Concerning The Nature of that Relation; with Observations upon the Opinions of Dr. Brown and Mr. Lawrence, Connected with the Same Subject. London: Printed for T. Hookham, 1824, and Essays on the Perception of an External Universe and Other Subjects Connected. London: John Hatchard and Son,1827. Hereafter cited as Shepherd (1824) and Shepherd (1827), respectively. 2 The Cambridge insert indicates that Shepherd's third treatise was published in 1819 under the title Enquiry Respecting the Relation of Cause and Effect. Whether or not such a treatise does in fact exist, the title itself suggests that the work might well have been quite similar to the treatise on causality published in 1824. 3 One other article has been written on Mary Shepherd. Margaret Atherton. 'Lady Mary Shepherd's Case Against George Berkeley' in the British Journal for the History of Philosophy 4 (2) 347-366 S 96. 4 Mary Shepherd's daughter's memoirs are unpublished and held in a private collection by her relatives. 5 Several catalogues describing library holdings at Barnbougle Castle and other family residences have been published. Built in the thirteenth century on her family's Dalmeny property in Queensferry, and set on the edge of Scotland's Firth of Forth, Barnbougle Castle was one of Shepherd's principal residences during childhood. 6 Marjorie Plant. The Domestic Life of Scotland in the Eighteenth Century. Edinburgh: Edinburgh University Press, 1952, pp.13-18. Plant paints a vivid but rather bleak picture of the eighteenth century domestic life of Scottish girls. Few girls received any education to speak of, and a typical day might be split between activities such as sewing shirts, reading scriptures, writing letters, taking walks, and the occasionally game or amusement. Only the most fortunate of Scottish girls of aristocratic heritage would have had access to their brother's tutors. 7 Jane Rendall. The Origins of Scottish Enlightenment. New York: St. Martin's Press, 206-236. Hereafter cited as Rendall. 8 David Hume to Allan Ramsey, April or May 1755, Letters of David Hume. Edited by J.Y.T. Greig. Oxford: Clarendon Press, Vol. I, 1969, pp. 219-221. The pursuit of philosophy was evidently very much au courant by the time the young Mary Primrose was old enough to take an interest, so much so that both the medical and the arts students at the University of Edinburgh complained of the bias in the curriculum in favor metaphysics. See Rendall, pp. 230-231. 9 The following excerpt from p. 46 of Shepherd's 1827 treatise is both telling of her critical approach to the great thinkers of the early modern period and indicative of the breadth of her knowledge: Thus some philosophers make God create all the images at the moment they appear in every mind. [Malebranche] Others conceive there is a pre-established harmony between the qualities of the external object, and our inward perception of it? [Leibniz] One considers the sensations arising from some of the senses to exist outwardly, but not those of others, arising from the rest of the senses. [Reid] Another gives up all outward existence whatever of objects and qualities. [Berkeley] And some suppose that if there be such things, that unless they be like our sensations, they are not worth talking about. [Hume]. 10 Mary Shepherd also published two articles in response to the philosophy of John Fearn: 'Observations on Mr. Fearn's Lines of the Human Mind', in Parriana: or Notices of the Rev. Samuel Parr, L.L.D.. Edited by E.H. Barker. London: Henry Colburn, 1828, 624-627, and 'Lady Mary Shepherd's Metaphysics' in Fraser's Magazine for Town and Country, Vol. V, No. XXX (July 1832) pp. 697-708. 11 Shepherd (1827) p. xii. 12 Shepherd (1827) p.114. 13 George Berkeley, The Principles of Human Knowledge. Edited by A.A. Luce and T.E. Jessop. London: Nelson, 1967, p. 42. Hereafter cited as Berkeley. 14 Berkeley, pp. 43-44. 15 Berkeley, p. 52-53. 16 Shepherd (1827) p.199. 17 Shepherd (1827) p.199. 18 Shepherd (1827) pp. 200-201. 19 Shepherd (1827) p. 216. 20 The following quote from pp. 5-6 of her 1824 treatise shows that Mary Shepherd was well aware of past controversies surrounding the philosophy of David Hume in Edinburgh society: It is not many years since Mr. Hume's notions were the occasion of much dispute, on the very ground on which I have undertaken it; a dispute which nearly lost the mathematical chair in one of our universities to the present possessor of it, on account of his favouring this doctrine. His opinion, however, as far as it related to any countenance it might afford to the principles of atheism, was defended by a learned treatise, from the then Professor of Moral Philosophy, in the same University. This treatise, whilst it controverts Mr. Hume's opinions in some respects, denies that atheistical inferences may be deduced from them; but I shall endeavour to show, that, in this respect, the author wanted observation and acuteness; neither perceiving the corollaries that go along with the doctrine, nor detecting the sly and powerful sophistry of the reasoning by which they are supported. 21 Shepherd (1824) pp. 27-28. 22 Shepherd (1824) p. 30. 23 Shepherd (1824) p. 49-50. 24 Shepherd (1824) p. 30. 25 Shepherd (1824) p. 38. 26 Shepherd (1827) p. 169. 27 Shepherd (1827) p. xv. 28 Shepherd (1827) 131. 29 Shepherd (1827) p. 125 30 Shepherd (1827) p. 131. 31 Shepherd (1827) pp. 126-127. 32 Shepherd (1827) p. 232 and p. 138. 33 Shepherd (1827) p. 325. 34 Shepherd (1827) p. 131. 35 Shepherd (1827) p. xvi. 36 Berkeley, p. 41. 37 Shepherd (1827) pp. 133-134. 38 Shepherd (1827) pp. 199-200. 39 Shepherd (1827) pp. 134-135. 40 Shepherd (1827) pp. 71-72. 41 Shepherd (1827) pp. 197-198. 42 Shepherd (1827) pp. 72-73. 43 Shepherd (1827) pp. 33-34. 44 Shepherd (1827) pp. 231-232. 45 Shepherd (1827) pp. 243-244. 46 Shepherd's full list of qualities is actually longer than this. On p. 168, Shepherd's list reads ''variety', 'independency', 'existence', continued existence', identity and so on'. 47 Shepherd (1827) p. 182 48 Shepherd (1827) p. 94. 49 Shepherd (1827) pp. 80-81. Shepherd writes that We gain the notion of the independancy of objects, from the observation of one object affecting many minds in a manner which renders it impossible there should be as many objects as minds. If five men see a pond, and can only walk round one pond, then there is one pond seen five times over, not five ponds; so the pond whatever it may be when unperceived, must at least in its unperceived state, be independant of, and I may add external to all the minds ; for if the pond were only in the mind, there would be five ponds, and every person who perceived a pond would create another pond, and yet this multitude of ponds in perception, would in many respects but merit the definition due to one pond. Thus there would be such a contradiction between "ideas and sensation," that the mind must come to the belief of only one pond, seen by five persons; that is, in other words, an independent cause for particular sensations. This objection to his doctrine Berkeley answers, in a very unsatisfactory, hesitating manner in his dialogues. 50 Shepherd (1827) p. 121. 51 The interpretation and assessment of Shepherd's reply to Berkeley in this paper differs from that of Margaret Atherton. Atherton passes a largely negative judgment on Shepherd's arguments. My positive judgment is based on the view that Shepherd's analysis of causation plays a central role in her response to Berkeley. See Margaret Atherton. 'Lady Mary Shepherd's Case Against George Berkeley' in the British Journal for the History of Philosophy 4 (2) 347-366 S 96. 52 See Bertrand Russel, A History of Western Philosophy. New York: Simon and Schuster,1945, Ch. XVI. 53 Harry Bracken. The Early Reception of Berkeley's Immaterialism: 1710-1733. Martinus Nijhoff, The Hague, 1959, p.89. Hereafter cited as Bracken. 54 Bracken, p. 37 55 Bracken, p. 37. 56 Bracken, p. 87. 57 On p. 32, Bracken cites Luce's remark in 'The Berkelian Idea of Sense' Aristotelian Society Supplementary Volume, XXVII (1953), p. 7: But for Scotland Berkeley might have died the second death. During his lifetime and for the greater part of the first century after his death Scottish philosophers took charge of him, and placed and kept him on the map. 58 Three quarters of a century earlier, in his article entitled 'Existence' in D'Alembert's Encyclopedia, AnneRobert Jacques Turgot advised that an analysis of causation must be central to any adequate reply top Berkeley. 59 Shepherd (1827) pp. 232-233 60 David Hume. A Treatise of Human Nature. Edited by L.A. Selby-Biggs. Oxford: Clarendon Press, 1980, p. 157, and An Inquiry Concerning Human Understanding in The Philosophy of David Hume. Edited by V. Chappell. New York: Random House, 1963, p. 327-330. Immanuel Kant. The Critique of Pure Reason. Edited by N. Kemp-Smith. London: Macmillan, 1929, (B 289). 61 Shepherd (1824) p. 27 62 Hume's subjectivist conclusion is that the necessary connection implicit in our ideas of cause is a subjective fiction ascribed by the mind when it perceives a constant conjunction of certain sensible qualities. 63 Shepherd (1827) p. xv. 64 Shepherd (1827) pp.107-108. 65 Shepherd (1827) p.131. 66 Shepherd (1827) p.70. 67 Shepherd (1827) p. 207. 68 Shepherd (1827) p. 59. 69 Shepherd (1827) pp. 138-139. Shepherd expresses the view that our ideas of extension and empty space must be linked to perception. She holds that motion enables us in the first instance to detect the 'outwardness' of objects, and that extension is not conceivable when unperceived either by the senses or the imagination. (164) 'Motion considered in relation to empty space is also perceived to be in relation to a mode of existence' and 'we prove empty space by the same reasoning, to be continually existing.' (175)