The Problem of Skepticism in Early Modern Philosophy of Consciousness

This post is part of a larger project I am working on: a critique of the epistemologically motivated Idealisms of Berkeley, Kant, and the post-Kantians. I am greatly attracted to Idealism, but I think we should accept it primarily on ontological grounds, i.e. because Idealism gives the best explanation of why reality exists and why it is as it is. Hence my criticism of the Idealisms of Berkeley, Kant, et al., because for them Idealism was primarily epistemologically motivated, Idealism being their solution to the problem of epistemological skepticism as it arose within the early modern philosophy of consciousness advanced by Descartes, Locke, and their followers. As I will argue in a next post, modern Idealism, as an answer to this threat of skepticism, fails miserably (thus the only remaining reasons for accepting Idealism must be ontological). To prepare the way for this critique of epistemological Idealism, this post explains how the problem of skepticism arose in the early modern philosophy of consciousness, or the “Way of Ideas” as it was known to Descartes, Locke and their contemporaries. 

The Way of Ideas
There were two main, interconnected forces driving early modern philosophers towards the Way of Ideas and its epistemological centralization of consciousness. One of these forces was the desire for certain knowledge, which arose from the quarrels between the Church and the new natural science of Copernicus and Galileo, which rose all kinds of thorny issues concerning the authority of Faith and the powers of Reason. Here, famously, Descartes used the cogito ergo sum argument as a way to ground the certainty of knowledge on the self-evidence of consciousness’ knowledge of itself. Thus, the range of certain knowledge became limited to individual consciousness and its ‘contents’ (generically called “ideas” or “representations”; Kant spoke of “Vorstellungen”). According to the proponents of the Way of Ideas, then, the subject knows primarily what is inside the “circle” of his consciousness; only those contents are immediately present to it. All things outside consciousness are known mediately, by conjecture on the basis of what is inside consciousness (sensations, feelings, concepts, thoughts).

The other force that drove early modern philosophers to embrace the Way of Ideas was the atomism – or “corpuscular philosophy” – of the new natural science. Reviving (and transforming) the atomism of Democritus, the proponents of the new science advanced the hypothesis that all natural phenomena are explainable in terms of tiny particles of matter, “corpuscles”, interacting mechanically in space. This, however, led to the question of how to explain sensory qualities such as colour, smell, sound, and taste, which are notoriously subjective. What colour something appears to have or how it sounds, tastes or smells can differ from person to person, depending on one’s physical constitution and the surrounding environment (thus, a thing’s colour changes with the light falling on it; things can taste and smell differently when you are sick, etc.). However, like the atoms of Democritus, the corpuscles of the new science were supposed to exist objectively, independently of our consciousness of them. They were, moreover, supposed to be so small as to be imperceptible and thus as being in themselves without colour, taste, smell, etc. Hence, like Democritus, the corpuscularians – including Descartes and Locke – concluded that such sensory qualities were merely the effects in our minds of the collisions of corpuscles on our sense organs. Such sensory qualities, then, are only subjective and do not reveal the objective qualities of the corpuscles, which consist merely of solidity, spatial form and position, and motion. This distinction between subjective and objective qualities became known as the distinction between secondary and primary qualities. Whereas the primary qualities, such as spatial position and motion, are objective, measurable, and mathematizable, and thus are crucial to natural science, the secondary qualities convey no trustworthy information about the reality outside our consciousness.

The general picture that thus arose was of a knowing subject locked inside his “circle of consciousness”, with external objects impinging on it from the outside, causing perceptions within the circle. “We have no knowledge of what is outside us except by mediation of the ideas within us,” as the Cartesian philosopher Arnauld (1964 [1662]: 31) summarized it. Such was the overall conceptual framework within which the Way of Ideas operated. And although this focus on consciousness was partly motivated, notably in Descartes, to provide a secure foundation for knowledge, the irony of the situation was that the Way of Ideas ended up fostering a radical epistemological skepticism. For if certainty pertains only to what is inside consciousness, how then can we know what is outside consciousness, the external reality? If all we know with certainty are the contents of consciousness, how can we know that these contents correspond to external objects? After all, as the problem was frequently put, we cannot step outside our consciousness in order to inspect its correspondence, or lack thereof, with external reality. 

The Veil of Perception and the Cartesian Circle

The problem is sometimes put in terms of a veil-of-perception theory which has been attributed to Descartes, Locke, and other philosophers of the Way of Ideas. On this theory, our sensory experiences of external objects do not give us cognitive access to these objects but rather form a ‘veil’ or ‘screen’ hiding them from our view. So the medium we use to know external objects, our sensations and ideas, blocks our very access to them. Thus Barry Stroud describes Descartes’ sceptical conclusion in his First Meditation as “implying that we are permanently sealed off from a world we can never reach”: “We are restricted to the passing show on the veil of perception, with no possibility of extending our knowledge to the world beyond. We are confined to appearances we can never know to match or deviate from the imperceptible reality that is forever denied to us.” (Stroud 1984: 33-4) Similar veil-of-perception theories have been attributed to Locke, Berkeley and Hume (cf. Bennett 1971).

The radical nature of the epistemological problem created by this veil-of-perception theory is well illustrated by the desperate solution offered to it by Descartes. In his Meditations on First Philosophy he famously argued that the only way to ‘pierce through’ the veil of perception, in order to reach the objects in themselves, is by evoking God, whose goodness would guarantee the veracity of our perceptions, such that “all things which I perceive very clearly and distinctly are true” (Descartes 1996 [1641]: 24). But to this solution, of course, the skeptic can easily respond by asking how Descartes can know for sure that God exists. If our ideas form a screen between us and external reality, then surely they would also screen us from the true nature of God, if He exists at all. Descartes had an answer to this, but few would find it convincing. It could even be argued that it is downright circular. Descartes argued that we find within our minds an idea of an infinite being, thus an idea which we as finite beings cannot possibly have produced; thus, it can only have been put in our minds by our Creator, “like the mark of the workman imprinted on his work” (Descartes 1996 [1641]: 35). Descartes’ assumption, however, that a finite being cannot form any idea of infinity, is rather questionable. Therefore Descartes also had recourse to a version of the ontological proof of God’s existence. But, as was already pointed out by critics in Descartes’ time, this makes his argument for the veracity of clear and distinct ideas rather circular. For Descartes cannot know that this proof of God does not contain any error unless he assumes that his clear and distinct perception of the steps of his reasoning guarantees that the proof is correct. So Descartes has to presuppose the veracity of clear and distinct ideas in order to prove the existence of God, which he then invokes as the guarantee of this very veracity – a conundrum known as the “Cartesian circle”.

The Problem of Primary and Secondary Qualities in Democritus, Locke, and Berkeley
The Way of Ideas, then, fostered epistemological skepticism by imprisoning the knowing subject within the circle of his consciousness, hiding external reality behind a veil of perception. It is often said that this type of skepticism was exclusively modern and cannot be found in premodern times. This is by and large true, but not entirely. It is true that for Pyrrhonism, the dominant form of epistemological skepticism in antiquity, the gap between what is in consciousness and what outside it didn’t matter much (Pyrrhonism was mainly concerned with showing that we can have no definitive criterion of truth, since every proof of such a criterion must either be circular or presuppose another criterion of truth, for which then the same problem arises). Nevertheless, the problem of the gap between consciousness and external reality was not completely unknown in classical philosophy, as shown by the remarkable case of Democritus, the "laughing philosopher". Not only did Democritus, with his atomism, anticipate the modern scientific worldview, he also anticipated the modern distinction between primary and secondary sensory qualities, as well as the epistemological skepticism induced by this distinction. In one of the few surviving fragments of his work, Democritus stages a striking dialogue between the Intellect and the Senses:

“Intellect: By convention there is sweetness, by convention bitterness, by convention colour, in reality only atoms and the void.
 Senses: Foolish intellect! Do you seek to overthrow us, while it is from us that you take your evidence?” 

In other words: if the secondary qualities do not convey objective information about the atoms, how can we ever know about them? How, in particular, can we know their primary qualities, since we cannot experience a thing’s spatial position and motion apart from its colour, sound, etc. If we disregard all secondary qualities, external objects become utterly unobservable to us. This means, as Democritus realized, that the atomic theory undermines the very credibility of the empirical evidence on which it rests. Democritus’ point was later repeated by early modern philosophers, notably Berkeley in his critique of Locke. 

Locke conceded that secondary qualities give us no insight into the true nature of external objects, but like Descartes he remained steadfast that we can nevertheless know these objects by observing their primary qualities, e.g. spatial position and motion. Thus Locke claimed that “the ideas of primary qualities of bodies are resemblances of them, and their patterns do really exist in the bodies themselves, but the ideas produced in us by these secondary qualities have no resemblance to them at all” (Locke 1996 [1689]: 51). Berkeley objected – much as Democritus had argued some 2000 years earlier – that we can observe a thing’s primary qualities only through its secondary qualities, and thus that our beliefs about the primary qualities of external objects are as problematic as the secondary qualities we attribute to them. Thus, Berkeley writes: “In short, extension, figure, and motion, abstracted from all other qualities, are inconceivable. Where therefore the other sensible qualities are, there must these be also, to wit, in the mind and nowhere else.” (Berkeley 2003 [1710]: 35)

Locke and the Problem of the ‘Thing in Itself’
In this way, however, Berkeley only aggravated a skepticism that was already present in the inaugurators of the Way of Ideas. We have already seen how Descartes felt the sceptical challenge and how he attempted to meet it by invoking God as the guarantor of the veracity of his “clear and distinct ideas”. Locke, too, felt this challenge. Although Locke thought (pace Berkeley) that we can know an external thing’s primary qualities, he also thought that we could not know what that thing is in itself, independent from its relation to us and other objects. Primary qualities, after all, are thoroughly relational, pertaining to a thing’s position in space and motion relative to other things. But what is an external thing in itself, apart from those relations? This, as Locke conceded, we cannot know, since we are ‘locked’ (pun unintended) inside our consciousness and cannot inspect objects as they exist outside of consciousness. Thus, what a thing is in itself, what the Aristotelians called its “substance”, was for Locke merely a “supposed” something “I know not what” (Locke 1996 [1689]: 123). For Locke, therefore, even the new natural science, despite its huge empirical success in the work of Galileo and Newton, yielded only opinion, not knowledge. Such sceptical modesty concerning the success of the new physics was in fact widely shared in early modernity, even by those who were directly involved in the development of the new science, such as Mersenne and Gassendi in France and John Wilkins in England. For all of them, our ‘imprisonment’ in consciousness precluded any knowledge about the true nature of external reality. 

Hume’s Critique of Causality
The authority of epistemological skepticism was further cemented by David Hume, who specifically undermined the causal claims of natural science, i.e. the claim that the scientist’s “laws of nature” refer to real causal connections within external reality. Hume followed Locke in holding that all belief begins with “impressions”, i.e. sensations, passions, emotions, which are the primitive imprints of external objects on our passive sensibility. We then form “ideas” which are the recollections of these impressions, their “faint images” or “copies” in memory. Hume argued that what guides us in these recollections of impressions, and thus in the formation of ideas, is the associative law of similarity: impressions which are sufficiently similar to each other get mutually associated, and thus form an idea. For example, our sense impressions of particular fires start over time to evoke recollections of each other due to mutual association, and this gives us the general idea of fire. Finally, beliefs emerge because these ideas, too, get linked to each other on the basis of association. To give an obvious example: in the past we have often experienced one sort of impression, e.g. of smoke, as immediately following upon another kind of impression, e.g. of fire, and this causes the general idea of smoke to become associated with the general idea of fire. This, according to Hume, is the full extent of what we mean when we say “fire causes smoke”. There is nothing more to our concept of causality, according to Hume, than this regular, inductively based association of one idea with another:

“We have no other notion of cause and effect, but that of certain objects, which have been always conjoin’d together, and which in all past instances have been found inseparable. We cannot penetrate into the reason of the conjunction. We only observe the thing itself, and always find that from the constant conjunction the objects acquire an union in the imagination. When the impression of one becomes present to us, we immediately form an idea of its usual attendant […].” (Hume 2003 [1739-40]: 67)

For Hume, then, the necessity we associate with the laws of causality, i.e. the idea that if one thing happens then another thing must happen, is nothing but the strength of this association, the power exerted by habit over the workings of our minds. We project this feeling of necessity onto the world, seeing the connection between one object and another as a necessary link between cause and effect. But, according to Hume, this is just an illusion, albeit a very powerful one. If we analyse our ideas more closely, Hume argued, we find no intrinsic connection between them that could substantiate a causal claim, such as that fire causes smoke. Imprisoned as we are within the circle of consciousness, we cannot know the real causal connections between external objects, if there are any at all. All we can know, Hume concludes, are the impressions and ideas of those objects within consciousness, and the merely associative connections between those impressions and ideas. Thus the causal laws of natural science evaporate into subjective feelings of necessity as we have been habituated to associate one idea with another.

The Mind-Body Problem and the Crisis of the Causal Theory of Perception
In sum, the Way of Ideas fostered epistemological skepticism by imprisoning the knowing subject with the circle of consciousness, hiding external reality behind a veil of perception. But it fostered such skepticism also in another (though closely related) way, namely, by inviting the mind-body problem. For how can mind interact with the external and supposedly material world if they are so very different, as the Way of Ideas suggests? The external world, after all, insofar as we can know it, is knowable only through its primary qualities, such as solidity, spatial position, and motion. For all we know, therefore, external reality is nothing but solid bodies interacting mechanically in space. Hence, of course, Descartes’ definition of the external world in terms of “res extensa”. But consciousness is very different from this world of extension, since ideas appear to have no solidity, no weight, no well-defined spatial position (if ideas can be said to be in space at all, they must be somewhere in my head, but where exactly?), and they do not interact by bumping into each other as material bodies do. Moreover, the conscious subject appears to have the capacity for free will, but free will seems impossible in a material world governed by causal determinism (pace Hume). Thus, consciousness appears to be in an entirely different realm of being, the immaterial realm of “res cogitans” as Descartes put it. Locke, too, drew the conclusion that mind must be immaterial, and thus categorically different from the material world which we can know through its primary qualities.

But, to repeat, if mind and matter belong to ontologically distinct realms, how can they possibly interact? Descartes wavered on this question, sometimes allowing mind-body interaction in the pineal gland, at other times doubting the possibility of such interaction; to Princes Elisabeth of Bohemia, with whom Descartes corresponded extensively, he admitted that this problem vexed him greatly and that he had no good solution to it. Locke was more resolute in that he openly declared the problem insoluble, there being no possibility for mind and matter to interact, except through divine intervention. As Locke argued, all you can get from spatial form and motion are other spatial forms and motions, and since the contents of consciousness are neither spatial forms nor motions, they cannot be caused by matter; nor can they exert causal influence on matter. However, since mind and matter obviously do interact, Locke felt compelled – much like Descartes in his solution to the problem of skepticism – to invoke God, who must have “superadded” mysterious properties to material objects, over and above their essential primary qualities, rendering them capable to cause sensations and ideas. Thus in his Essay Concerning Human Understanding, Locke writes:

“[B]ody as far as we can conceive being only able to strike and affect body; and Motion according to the utmost reach of our Ideas, being able to produce nothing but Motion, so that when we allow it to produce pleasure or pain, or the Idea of a Colour, or Sound, we are fain to quit our Reason, go beyond our Ideas and attribute it wholly to the good pleasure of our Maker.” (Locke 1996 [1989]: 237)

Obviously, no skeptic will be persuaded by this appeal to God in order to explain mind-body interaction. That Locke feels compelled to invoke divine intervention in this context only goes to show the deepness of the problem. And apart from being an ontological problem concerning the place of mind in the material world, it is also an epistemological problem, and one that aggravates the skepticism already induced by the Way of Ideas. For insofar as the causal interaction between matter and mind becomes mysterious, it becomes equally mysterious how perceptions can convey information about external objects. For here the only possible theory seems to be some version of the causal theory of perception, such that perceptions carry information about external objects because they have been caused by these objects, i.e. by the impingements of material objects on our external sense organs. Locke accepted a causal theory of perception, and he used it to explain how we can know external objects. Although the secondary qualities caused in our minds by external objects do in no way resemble those objects, as Locke admits, the situation is different with the primary qualities, i.e. with our perceptions of solidity, spatial position, figure, motion, etc. Here, according to Locke, our perceptions do resemble the objects by which they have been caused. By causing perceptions in us, then, external objects convey to us information about their primary qualities. And, for Locke, this is the only way we can know external objects, since according to him all knowledge starts with sensory impressions, the mind being a tabula rasa prior to experience. Hence the dire consequences of the mind-body problem. If the causal interaction between mind and matter becomes mysterious, to such an extent even that we need to invoke divine interaction to explain it, then clearly the causal theory of perception is of little help in explaining the veracity of our perceptions. Due to the mind-body problem, then, the epistemic position of the subject under the Way of Ideas deteriorates even further: not only is the subject shielded from external objects by a veil of perception, imprisoned in the circle of consciousness; the only way for external objects to pierce through that veil – by causing perceptions in us that resemble their primary qualities – falls away by being a complete mystery. And even if we accept mind-body interaction as an unexplainable yet undeniable given, we still have the problem raised by Berkeley (following Democritus) that we really have no perception of primary qualities apart from secondary qualities… 

References

-Arnauld, A. (1964 [1662]), The Art of Thinking. Indianapolis: Bobbs-Merrill.

-Bennett, J. (1971), Locke, Berkeley, Hume: Central Themes. Oxford: Oxford University Press.
-Berkeley, G. (2003 [1710]), A Treatise Concerning the Principles of Human Knowledge. Mineola: Dover Publications.
-Descartes, R. (1996 [1641]), Meditations on First Philosophy. Cambridge: Cambridge University Press.
-Hume, D. (2003 [1739-40]), A Treatise of Human Nature. Mineola: Dover Publications.
-Locke, J. (1996 [1689]), An Essay Concerning Human Understanding. Indianapolis: Hackett Publishing Company.
-Stroud, B. (1984), The Significance of Philosophical Scepticism. Oxford: Oxford University Press.