Sensible Ideas: The Knowledge Behind the Perception
Do objects exist independently of consciousness? If so, what is the nature of these objects? These questions shall be investigated through the conflicting philosophies of John Locke and George Berkeley.
Preliminary Quotations from Locke and Berkeley:
Primary Qualities of Bodies -- Qualities thus considered in bodies are, First such as are inseparable from the body, in what state soever it be; and such as in all the alterations and changes it suffers, all the force can be used upon it, it consistently keeps; as such as sense constantly finds in every particle of matter which has bulk enough to be perceived; an the mind finds inseparable from every particle of matter... These I call original or primary qualities of body, which I think we may observe to produce simple ideas in us, viz. solidity, extension, figure, motion or rest and number. (Locke, p24,25)
Secondary Qualities of Bodies -- Secondly, such qualities which in truth are nothing in the objects themselves but powers to produce various sensations in us be their primary qualities... (Locke p25)
No clear or distinct idea of Substance in general -- Hence, when we talk or think of any particular sort of corporeal substances, as horse, stone, &c., though the idea we have of either of them be but the complication or collection of those several simple ideas of sensible qualities, which we used to find united in the thing called horse or stone; yet, because we cannot conceive how they should subsist alone, nor one in another, we suppose them existing in and supported by some common subject; which support we denote by the name substance [substratum], though it be certain we have no clear or distinct idea of that thing we suppose a support. (Locke p54)
As to myself, I think God has given me assurance enough of the existence of things without me: since, by their different application, I can produce in myself both pleasure and pain, which is one great concernment of my present state. This is certain: the confidence that our faculties do not herein deceive us, is the greatest assurance we are capable of concerning the existence of material beings. For we cannot act anything but by out faculties; not talk of knowledge itself, but by the help of those faculties which are fitted to apprehend even what knowledge is. (Locke p106)
... by sensible things I mean those only which are perceived by sense, and that in truth the senses perceive nothing which they do not perceive immediately: for they make no inferences... (Berkeley p221)
If it be allowed that no idea nor any thing like an idea can exist in an unperceiving substance then surely it follows, that no figure or mode of extension, which we can either perceive or imagine, or have any idea of, can be really inherent in matter; not to mention the peculiar difficulty there must be in conceiving a material substance, prior to and distinct from extension, to be the substratum of extension. (Berkeley p235)
To be plain, it is my opinion, that the real things are those very things I see and feel, and perceive by my senses. ... That a thing should be really perceived by my senses and at the same time not really exist, is to me a plain contradiction; since I cannot prescind or abstract, even in thought, the existence of a sensible thing from its being perceived. (Berkeley p273)
And I should have not known [objects], but that I have perceived them by my senses; and things perceived by the senses are immediately perceived; and things immediately perceived are ideas; and ideas cannot exist without the mind; their existence therefore consists in being perceived; when therefore they are actually perceived, there can be no doubt of their existence. (Berkeley p274)
When I deny sensible things an existence outside the mind, I do not mean my mind in particular, but all minds. Now, it is plain they have an existence exterior to my mind, since I find them by experience independent of it. There is therefore some other mind wherein they exist, during the intervals between the times of my perceiving them: as likewise they did before my birth, and would do after my supposed annihilation. And as the same is true with regard to all other finite created spirits, it necessarily follows, there is some omnipresent, external Mind, which knows and comprehends all things, and exhibits them to our view in such a manner, and according to such rules as he himself hath ordained, and are by us termed the laws of nature.
Sensible Ideas: The Knowledge Behind the Perception
Before considering the existence of objects independent of consciousness, an understanding of the nature of these objects should be undertaken. Clearly, all who possess unimpaired sense organs, perceive collections of sensible ideas. These ordered, distinct, lively and forceful collections of ideas, commonly referred to as objects, are perceived independently of the will of an observer. They represent the only directly obtainable knowledge of objects one may acquire. Intuitively and commonly, this is knowledge of actual, existing, physical objects. Such a view, while mentally appeasing, is far from logically necessary. The dispute as to what sensible ideas represent embodies the major conflict between Lockian and Berkelean philosophies.
According to Locke, objects possess active powers (qualities) to create certain sensible ideas in perceivers. These powers are of two sorts -- primary qualities and secondary qualities. Primary qualities are those permanent powers inherent in an object to represent the object's true nature (its present solidity, extension, figure, motion or rest, and number) to an observer. Secondary qualities are merely those powers (determined by the primary qualities) to represent the variable properties of the present state of an object to a perceiver (such as the coldness of water in the form of ice). Thus collections of sensible ideas presented to one's mind are created either directly or indirectly by the object's inherent primary qualities. Clearly, according to Locke, sensible ideas are only representations of objects. Likewise, objects do not consist solely of primary qualities since they are only attributes requiring something in which to inhere. Locke provides this something in the form of an unthinking, insensible substratum in which the primary qualities of all objects inhere. Locke's immediate justification for substratum consists simply in the fact that if qualities exist, they must be supported by something -- even though he knows not what.
Locke is a realist and an empiricist. As such, he ardently believes in the existence of objects independently of one's consciousness. He also believes that all ideas are either sensible or the result of reflection on sensible ideas. Locke the empiricist should not consider introducing the insensible, metaphysical idea of substratum. While he could argue that substratum is an idea abstracted from sense experience, there is still no logical necessity for its existence, even if one concedes to man the ability of abstraction, which Berkeley would not. Locke even admits, in his essay, that one can have no understanding of the nature of substratum. In attempting to ground his realism, it is clear that Locke has introduced unjustified concepts into his philosophy. Locke also bases his philosophy upon the supposition that one can perform some sort of inference from sensible ideas to real, insensible physical properties of objects which he supposes they represent. Berkeley would say that such an inference, being neither deductive nor inductive, is impossible. However, there may be some theoretical inference from the sensible to the insensible, although Locke has not even touched upon the topic.
Berkeley, on the other hand, holds that what one perceives to be objects are no more than those same collections of sensible ideas perceived. There do not exist material or immaterial insensible things that produce these sensations, the sensations themselves are the objects. This principle of immaterialism, that physical objects are objects of immediate perception, seems somewhat naive and simplistic. Berkeley is implying that awareness of objects (perceptions) is independent of thought and will. It is not evident that physical objects are objects of immediate perception. In fact, this is as counter-intuitive as the existence of an insensible substratum pervading space. The Lockian perspective of mediate perception of objects is much more reasonable. Sensations are perceived immediately, but the mind interprets these sense perceptions in light of previous sense experience. It is these interpretations that one believes to represent existent physical objects. It may seem that this view is unjustified, but the existence of such objects is easily seen and shall be shown shortly.
As to the existence of material objects independent of consciousness, Locke and Berkeley employ similar arguments towards different ends. Locke, as mentioned above, believes that objects do, in fact, exist independently of minds (and thus consciousness). As proof, he brings forth several arguments. First, sensible ideas are caused by external force(s). This is evident from experience that those without certain sense organs never can produce ideas in their minds belonging to that sense. Also, the organs themselves do not produce sensible ideas. If they did, one could see color in a dark room or observe other "strange" phenomena. Second, ideas produced through actual sense experience are manifestly different from those of sense experience remembered. It is clear from experience that sensible ideas are forced upon one independently of one's will whereas memories can be examined or not at leisure. That remembrances are much less vivid and clear than actual sensible ideas is also remarkable. Third, sensible ideas create some degree of pleasure or pain at the time of perception that is not observed upon remembrance of the same events. Finally, each sense supports the other's observations to form a coherent complex (composite) idea of an object. Locke concludes with the assumption that one cannot distrust one's sensations to the extant as to doubt that collections of sensible ideas really exist together as perceived by one's senses. These preceding premises together with Locke's belief that God has assured him that his senses do not deceive constitute his proof of the existence of independently existing objects (a substratum with objects' primary qualities inhering within).
While each of Locke's premises are true, as Berkeley would agree, they only imply, as Locke himself states, that there exist external forces which produce sensible ideas in one at the time of perception. By rights, Locke should at this point attempt to justify his substratum with more than his superficial inability to conceive of another explanation to support his realism. Locke's real problem consists not in distrusting one's senses as much as in justifying an inference to his cause of sensual perception. Even allowing the possible reliability of one's senses, it does not follow that a substratum exists supporting the primary attributes of physical objects. It is conceivable that the sensible ideas are produced in one by some external thinking agent that has the power to produce a coherent perceptive world. Or, equivalently, they could be produced by value interactions between the subjects and objects as Robert Pirsig explains in his metaphysics of Quality.
George Berkeley uses the same evidences as Locke to prove the existence of some active external agent that produces sensible ideas in one. However, Berkeley's interpretation of sense perception differs greatly from Locke, as has been noted before. Berkeley argues that objects are only known as they are perceived by the senses. Things perceived by the senses are immediately perceived. That which is immediately perceived are ideas which cannot exist without the mind. The existence of the objects, therefore, consists in the perception of the objects. Therefore, when perceived, there cannot be any doubt as to the object's existence. Of course closing one's eyes and therefore no longer perceiving a person necessarily implying that that person no longer exists is absurd. According to Berkeley, as long as the object is perceived by some mind, the object exists. Berkeley assumes that objects continue to do so when he does not perceive them (for the sake of continuity). Likewise, he assumes the same presumption holds for all finite spirits (so there is nothing special about himself). Therefore, he concludes that it necessarily follows that there exists some omnipresent, external Mind, which perceives all things and has the power to cause perceptions of all objects in finite perceivers. This is Berkeley's God.
There are two major flaws with Berkeley's reasoning. First, as mentioned before, it is not evident that objects are perceived immediately. Berkeley may say that denying this leaves one in a skeptical position as to the existence of objects, but this is not so if one allows the existence of the aforementioned theoretical inference. Second, Berkeley does not adequately prove that God is the source of one's perceptions. That there exists an eternal, omnipresent perceiver, God, neither implies nor necessitates that this God is omnipotent nor that he is the one who has the power and does produce sensible ideas in finitly created perceivers.
In summary, both Berkeley and Locke's philosophical positions on objects and their existence fall short of a solid logical flow or basis. Locke's position comes closest to justification. One may assume that one possesses knowledge of objects (sensible ideas) mediately through comprehension of immediately perceived perceptions. One employs one's store of sense experience (memory) to mediately categorize or understand collections of sensible objects as representative of some known or unknown physical object. One can argue that one's memory (which can be assumed to truthfully represent one's past sense experience) in conjunction with Locke's four premises for an object's existence, provides the temporally and physically coherent sensible world necessary to imply the continued existence of independent objects. All that is needed to justify this argument is that one can, as Locke assumes, trust one's senses (that the sensible ideas perceived actually represent physical objects). If this premise is veridical, then the theoretical inference from sensible ideas to the insensible real nature of objects necessarily follows.
What would happen if one's senses were capable of deception? In such a case, the sensible ideas one obtains may not have any resemblance to their causes. Therefore the senses themselves somehow distort what could be considered to be a "true perception" created by some external force. Then, either our senses distort similar perceptions in the same manner, or they do not. In the latter case, one would constantly perceive anomalous occurrences -- things that contradict one's memories of similar occurrences. From experience, one can verify that this does not occur. Therefore, either one's senses do not deceive, or they distort "true perceptions" in some consistent way. In the latter case, a hypothetical independent observer, who could comprehend both "true perceptions" and one's consistently distorted perceptions, would notice that they both represent the same "object" from different view points. This can be seen through the analogy of performing a linear change of coordinates in geometry -- one can represent the same geometrical figures in an alternate coordinate system with the same accuracy as the original system. Therefore, to our finite perceptions, both ways of perceiving objects are effectively equivalent. To summarize, if faculties consistently distort "true perceptions," the resulting "world" would still be self-consistent and represent the objects just as accurately as the "true perceptions." Therefore, one may conclude that one's faculties do not deceive. As to whether or not these sense perceptions originated from actually existing objects or some other source (the mind of God), one can see that this question is really outside the sphere of possible human knowledge and therefore should not be considered. Since one's faculties do not deceive, and one is acted upon by outside forces to produce these sensible ideas, one may conclude that such independent physical objects really do exist independent of consciousness. Such knowledge is representative of the surest reality humans can know and thus should be accepted as veridical.
Essay based on Lock's An Essay Concerning Human Understanding and Berkeley's Principles of Human Knowledge as found in The Empiricists, Anchor Books, published by Doubleday, 1974.
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