What is perception? And what is the connection between perception and the corresponding reality posited in naïve realism? This question was of great interest to many important Enlightenment thinkers and is reflected in the many novel approaches they took to the problem and is passed down to us even today in postmodernist doubts about perception and its connection to an objective reality. Among these, Leibniz, Berkeley, and Hume present us with a wide swath of philosophical approaches to the question that not only offer a diversity of perspectives, but can also provide a critique of each other as well. An evaluation of them would prove useful in considering our own beliefs about perspective and how we came by them.
For Leibniz, ontology is perspective; in the form of discrete units of being he called monads. The individual monad is the realization of one of an infinity of divine perspectives on the creation. Each of these is coordinated by the creative power of God so that all events, while represented by a distinct and causally independent perspective, nevertheless correlate between the individual perspectives realized in each monad. Thus, each monad is an independent world unto itself, operationally distinct from one another, and united only in a common bond to the divine will.1 Leibniz expresses this relationship by saying:
Thus God alone constitutes the relation or communication between substances. It is through him that the phenomena of the one meet and accord with the phenomena of the others, so that there may be a reality in our perceptions.2
Thus, the only proper causal relationship that exists is between the individual monads and the God who formed them. It is understood that all of our perceptions are immediately derived from God and constitute the only external contact possible for a monad. Additionally, these perceptions are not only derived from God, but are themselves a reflection of the divine essence and will, which explains how we are able to know all other substances in the universe.3 All other so called relationships are causal in name only, being rather an increase of phenomena in one substance with a corresponding decrease in the second substance, as dictated by God.4
Although there are no causal links between phenomena, it remains possible to predict future states based on the knowledge that all events perceived are functions of a monads essence. This means that each monad recapitulates within it all known phenomena,5 both of its own experiences as well as all attendant circumstances, of past, present and future. Because of this, it can be said that each monad exerts its power upon all other substances by virtue of their being present in its being, and is in turn acted upon by them through participation in their essences.6 As a consequence, the essence of any substance is understood to consist of nothing more than its perceptions and their changes.7 It is therefore impossible for a substance, or monad, to have no perception, since the end of perception would necessarily mean the end to the substance it constitutes.8
It is the distinct character of the various perceptions, varying in strength and clarity, which lend the individual monads their uniqueness.9 Because of this, each monad can reflect the same universe, whilst simultaneously doing so in a distinctive manner.10 Thus, while each essence carries with it the totality of all sensations, only a small portion of these can be attended to by the soul at any one time. It would thus be almost impossible to have a completely shared perspective on any one phenomenon, let alone all phenomena, due to the variety of possibilities presented to the individual.11
Berkeley believed human knowledge to be derived from perceptions of the senses, observations of the mind, or memories and imagination, which is itself a reconstitution of the first two.12 And whereas Leibniz had arguably but one mind, that of God, Berkeley allowed for multiple minds, since for him the mind was the basis, or principle, upon which perception existed.13 There could be no sensations or impressions unless there was a mind in which to impress them upon. Nor could there be any of the other mental activities that made up human knowledge without a mind to bear these impressions and allow for their manipulation and recombination.14 Thus, while for Leibniz existence was perception and the mind of God, Berkeley understood existence to be but one substance, the mind as a foundational substance, and its’ perceptions, in a secondary, conditional existence, subsisting in the mind.15
This is what he meant when uttering his famous phrase, esse est percipi, for since the mind grounds all existence, anything that did not subsist in the mind had no existence.16 He argued this position by pointing out that all we can know is our perceptions, of the various senses, or else of memories of those perceptions.17 But if sensations and the ideas founded upon them are all that can known, then how is it we can justify a belief in something existing outside of our perceptions, such as any underlying, yet unperceived, reality behind our perceptions?18 The error of naïve realism lies in the mistaken notion that the mind is somehow capable of extracting the imperceptible substance from our perceptions of the object, and so to discover what was not in their perceptions by means of those very same perceptions in which they failed to discover it.19
Berkeley thereby not only eliminates the problems associated with dualism, as displayed in the difficulties of coordinating interactions between the material and mental in the Cartesian system, but eliminates distinctions between primary and secondary qualities as well, for without an external substance to anchor the primary substances in, they are necessarily grounded in the same substance as the secondary qualities, namely the mind.20 Beyond this, even should their be mind independent substances, this would change nothing with regard to our knowledge of the world, since these imperceptible substances would lie outside the realm of the knowable, and so such a theory would propose elements that for all intent would serve no purpose within the ontological system and do nothing to expand our knowledge of the world beyond what is already attained in a system without them. Additionally, it would potentially create problems when trying to account for various phenomena in which there are clearly perceptions, but without any underlying material substance, e.g., dreams.21
Sensations and ideas functioned as inert elements within Berkeley’s immaterialism, as their content is dictated solely by what is perceived. It is only the mind that is active, performing various operations upon the perceptual objects available to it.22 Yet clearly there is a cause behind these sensations, since there is an unbroken succession of them, often with unanticipated content.23 But with nothing but the mental as a source which to attribute them, it becomes necessary to propose a governing mind; one governing the phenomena we perceive, which for our purposes may be called God.24 It is in these sensations which reality exists, pouring forth from the overseeing mind, and from which all other mental phenomena are derived.25
Hume proves to be an interesting contrast to Leibniz and Berkeley, a skeptic to their believer. For while all three agree that our knowledge must begin with perception, Hume questions our capacity to extend our knowledge beyond it, and so throws the whole metaphysical project into question. He begins his analysis with the drawing of a simple distinction between our perceptions. The first class are what he calls impressions, which can be further broken up into the external sensations and the internal passions of the mind. These are characterized by their immediacy and vivacious character. The second group of perceptions, named ideas, are memory, imagination, and the like. Being derived from the reconstituted elements of the previous class, these lack the force or intensity of the former.26
These recollected perceptions are based on the minds repertoire of impressionable experiences, which presents a clear limitation to the mind for creativity, since no idea can be produced which is not already present within the mind from sensations of one form or another.27 The principles that connect the ideas derived from these perceptions are fairly simple and can be classed into three broad categories; resemblance, contiguity, and causality, and typically work themselves out as some combination of one or more of these principles.28 These principles are applied to two general classes of reasoning, deductive (Relations of Ideas) and inductive (Matters of Fact). Deduced ideas are known through an analysis of the content of the ideas in question, whereas inductive reasoning is about matters that must be compared to outside observations in order to know the truth of them.29
It is this latter family of ideas that seems to operate solely under the principle of causality. There seems little argument that this is in fact how we can take our knowledge beyond the mere registering of sense perceptions and make predictions based on them; we make causal connections between one observed event and a succeeding observed event. For no one knows the causal relation between an object without having first observed it, or by drawing an analogy between it and observations of similar objects.30 And yet our perceptions have no necessary connection between them that we could point to as justification for our causal predictions. It is based neither on a priori knowledge, for we do not know causality but by experience, and yet experience, which is composed of perceptions, fails to give us the necessary link since there is no guarantee that similar perceptions be succeeded in similar ways. Rather, it is only by a matter of convention that we are able to draw analogous comparisons with current perceptions and past experience and so assume a parallelism in our conclusions.31
While Hume is certainly best known for his questioning of causation, each of the philosophers brings it, and the naïve realist perspective that underlies it, into question. For Leibniz, the monads have causally isolated, having “no windows” through which to interact with one another. And Berkeley completely abandons any connection between one perception and any causally predictive by relegating the existence of phenomena to divinely supplied perceptions. But Hume perhaps was the most consistent of the three, for he saw that if we really are to limit ourselves to perception, than reason has no recourse but to note each perception as a distinct, independent phenomena. Steps beyond this were marks of inconsistency and a sort of back door attempt at regaining the lost substance of naïve realism.
But is his conclusion the right one, that we ought to give up on the metaphysical enterprise altogether and confine ourselves to the pragmatic philosophy he advocates? I have to admit to finding Hume’s argument a compelling one, but at the same time, he seems both entirely too pessimistic regarding both the capacity of human learning as well as the importance of the speculative aspects of philosophy. A quick perusal of Hume’s dismissiveness towards certain philosophers or the abilities of science would appear to indicate that he has taken what seem to be his own predispositions too far in the direction of matters of fact with clearly insufficient basis. Perhaps a better approach would be to keep grounded in Humean pragmatisms’ awareness of reasons limitations while allowing for the speculative to push the boundaries, if not of knowledge of reality, than at least our perception of it. Who knows, it may just lead us to even more successful customs and habits than the ones we have currently. And this in itself would seem to constitute a rejection of the passive mind these philosophers advocated in favor of one that is a dynamic actor; shaping, and not just being shaped by, the world perceived around them.
1Discourse, sect. 14
2Discourse, sect. 32
3Discourse, sect. 28
4Discourse, sect. 15
5Discourse, sect. 14
6Discourse, sect. 9; Monadology, sect. 14
7Monadology, sect. 17
8Monadology, sect. 23
9Monadology, sect. 60
10Monadology, sect. 63
11Discourse, sect. 32
12Principles, part I, sect. 1
13Principles, part I, sect. 2
14Principles, part I, sect. 3
15Principles, part I, sect. 7
16Principles, part I, sect. 6
17Principles, part I, sect. 3
18Principles, part I, sect. 4
19Principles, part I, sect. 5
20Principles, part I, sect. 9
21Principles, part I, sect. 18
22Principles, part I, sect. 25,27
23Principles, part I, sect. 26
24Principles, part I, sect. 29
25Principles, part I, sect. 33
26Enquiry, sect. 11,12
27Enquiry, sect. 13
28Enquiry, sect. 19
29Enquiry, sect. 20,21
30Enquiry, sect. 24
31Enquiry, sect. 29
- Ariew, Roger, Eric Watkins, ed. “Leibniz, Discourse on Metaphysics.” Modern Philosophy: An Anthology of Primary Sources. Indianapolis: Hackett Publishing Company, Inc., 1998.
- Ariew, Roger, Eric Watkins, ed. “Leibniz, The Principles of Philosophy or the Monadology.” Modern Philosophy: An Anthology of Primary Sources. Indianapolis: Hackett Publishing Company, Inc., 1998.
- Ariew, Roger, Eric Watkins, ed. “Berkeley, Principles of Human Knowledge.” Modern Philosophy: An Anthology of Primary Sources. Indianapolis: Hackett Publishing Company, Inc., 1998.
- “An Enquiry Concerning Human Understanding.” Wikisource, The Free Library. 7 Sep 2009, 00:18 UTC. Wikimedia Foundation, Inc. 4 Nov 2009 <http://en.wikisource.org/w/index.php?title=An_Enquiry_Concerning_Human_Understanding&oldid=1216888>.