╬Twixt that, and reason, what a nice barrier,
Forever separate, yet forever near!
Remembrance and reflection how allied:
What thin partitions sense from thought divide:
And middle natures, how they long to join,
Yet never pass the insuperable line!
- from Alexander Pope's "An Essay on Man."
In this paper I shall argue that Locke may be defended in two significant ways from the charges of total skepticism that the ╬veil of perception' entails. First, I shall argue that Locke's theory is not a representative theory but a causal theory. Secondly, I argue that Locke's position entails a dilemma that effectively defends him against charges of total skepticism, by adjusting the criteria for knowledge away from certainty and towards probability.
According to the majority of accounts, Locke's theory of perception is a representative theory. Jonathan Bennett's ╬veil of perception' is an alternative name for the representative theory. Bennett adopts the former phrase because the latter "does not express what is wrong with the theory" [Bennett 69]. The term ╬veil of perception' refers to the fact that everything we are aware of is mediated by our senses. As we are only aware of things through our senses, it is as though we perceive through a ╬veil of perception'. In order to decide whether Locke's ideas constitute a ╬veil of perception' we must decide whether Locke's theory can be correctly construed as a representative theory. The representative theory of perception: we are only aware of the existence of external objects through the mediation of the ideas we have of them; we cannot say that we know that these ideas actually represent those objects; we cannot say we know that there are any external objects whatsoever. The representative theory of perception, the critics assert, leads to total skepticism.
It now remains to discover whether or not Locke's position entails the kind of gross skepticism that a purely representative theory of perception necessitates; there is evidence it does. For examples, I shall paraphrase two arguments that are interpreted as asserting, or entailing the representative theory of perception. First, in Book IV, Chp. II, Sec. 14, Locke presents an argument for " the particular existence of finite beings without us" [Locke p. 537].
This argument, to which I have added the suppressed premise three, may be easily criticized by anyone who takes the skeptical tack. Premise three asserts that ideas that are caused by external objects are more vivid; however, this premise begs the question, since it is the existence of external objects that is under contention. Locke cannot assert he knows that external objects exist because external objects produce his most vivid sensations. Hence, the critic asserts, Locke is left with a skeptical view. Another attempt Locke makes to show the existence of external objects occurs in Book IV, Chp. IV, Sec. 3-5. I have paraphrased it as follows.
In this case the critic would target premise six and assert, once again, that the premise begs the question. In order to assert that the idea in x exactly answers the power in body y, Locke requires some independent evidence beyond the evidence of his senses, because it is this latter evidence that is in question. Since we can not reach beyond the evidence of our senses in order to be certain whether or not they resemble or represent the world-as-it-is, we should not assert that we know they do, claims the critic. Once again, it appears, Locke's position entails skepticism. These arguments form the basis of the critiques of this interpretation of Locke's theory of perception.
Jonathan Bennett uses this kind of argument in his book, Locke, Berkeley, Hume, against Locke's position. Bennett states the problem as follows:
Bennett argues that unless we have some independent source of information about this outside realm, we are quite incapable of certainty regarding its nature, or even its existence. Is Locke's position untenable? One possibility that may yet save Locke is that perhaps he does not hold a representative theory of perception at all. If this is the case, then perhaps all the criticisms are aimed at a ╬straw man'. An alternate position that Bennett offers is that Locke may have a causal theory of perception. Although Bennett does not feel that this option releases Locke from his inevitable skeptical conclusions, in the interests of fairness I shall examine this possibility first, and reintroduce Bennett's criticisms immediately following.
First, we should determine what constitutes a causal theory of perception. In his book, Perceptual Knowledge: an Analytical and Historical Study, Georges Dicker states the classic causal theory of perception as:
Once we examine the evidence in Locke's An Essay Concerning Human Understanding, it becomes apparent that it does present a causal theory of perception. That ideas are caused by something exterior to mind is entailed by the fact that Locke feels there are no innate ideas. How then does Locke argue we come to have ideas? Locke's causal theory of perception is based on the principles of corpuscularianism: the belief that all things are made up of tiny particles called corpuscles. The activity of these corpuscles results in our ideas of the qualities of physical objects through direct causal interaction with the sensory organs themselves. In Book II, Chp. VIII, Sec. 4, Locke asserts that sensation is exclusively the result of "different degrees and modes of Motion in our animal Spirits, variously agitated by external Objects" [Locke p.133]. Evidence for his corpuscularianism is also found in Sec. 12:
In light of these passages and others in the text, it seems that Locke held a causal theory of perception. In accordance with the classic definition of causal theory, Locke justifies his claim to perceive M by arguing: ideas do not stem from the mind, therefore, physical objects must be causally required to account for ideas of physical objects. Specifically, these objects are required for our ideas of primary qualities. Locke states that he ╬cannot conceive' how it could be possible to have these ideas except through this causal relationship.
Jonathan Bennett claims that this theoretical shift does not really help Locke's situation at all. The objections to the causal theory of perception have exactly the same consequences as the objections to the representative theory of perception. Bennett's objection is that in order to know whether or not the causal chain exists, in the manner Locke believes it exists, Locke would require exactly the same kind of independent evidence that was required to know whether or not the world was correctly represented. Consequently, we have no more evidence for the existence of external objects that we did before we adopted the causal theory.
In opposition to Bennett, I argue that Locke presents a significant defense against the charges of skepticism. In the last section of Book I, after having denied the possibility of innate ideas or principles, Locke makes a statement that has far-reaching implications for a sympathetic reading of his text. I assert that this passage effectively sets up a dilemma that defends Locke against the charges of total skepticism.
This argument is not to be understood in the fairly simplistic sense of, ╬either Locke can prove his position or he cannot'; rather, the argument points to two different knowledge criteria in Locke's argument. On one horn of the dilemma, Locke feels that given certain principles, it is possible for him to reach deductively certain conclusions about the world-as-it-is. On the other horn, Locke recognizes that without these underlying principles, the drift into skepticism is inevitable. In response to the skeptic, however, Locke uses both inductive and pragmatic arguments to assert that we do have knowledge; though, it may not be certain.
According to the first horn of his dilemma, if we grant him his principles, Locke asserts that he is able to ╬demonstrate' his position. Demonstrative knowledge requires "a steddy application by steps and degrees, before the Mind can in this way arrive at Certainty" [Locke p532]. Demonstrative knowledge is a system of proofs in which each step is affirmed intuitively but whose final truth can not be revealed except by means of the intervening steps [Locke p. 533-4] Now that we know Locke's method, we must determine which principles he requires in order to demonstrate his position. These principles may be enumerated as follows:
If we are to give Locke a fair reading, we should examine his argument in light of these principles.
According to Locke's general principles, is he committed to the view that the fact that he is only immediately aware of ideas prevents him from ever having certain knowledge of the world-as-it-is? No. According to Locke's principles, he knows, from (i) and (ii) that ideas proceed from something external to mind since ideas cannot proceed from mind. He knows that he has ideas of extension, figure, motion, mobility and solidity. He knows , from (iv), that the ideas he receives from the world-as-it-is are the direct result of a physical causal chain that began with the objects themselves and culminated in his ideas of those things. Finally, Locke knows, from (iii), that the ideas he has of the primary qualities of objects really represent the qualities of the objects themselves. As for whether or not we can view secondary qualities without skepticism, Locke states explicitly that we cannot. However, it is clear that Locke cannot be accused of total skepticism on this horn of the dilemma.
How then does Locke fare on the other horn of the dilemma? It would seem that his position becomes instantly untenable. All his general principles are once again open to the skeptic's critiques. Principles iii) and iv) beg the question, once again, and Locke's argument quickly unravels as a consequence. However, the premise behind the second horn of the dilemma says that the reader "should not expect undeniable cogent demonstrations" [Locke p. 103]. This premise changes the knowledge criteria for Locke's argument and acts as a final defense against the charges of skepticism.
First, the charges: Principle iii) begs the question: Locke cannot reach beyond the knowledge of his senses to assert that that which lies external to his senses corresponds to his senses. Principle iv) also begs the question: Locke needs independent evidence to assert that he knows the nature of the causal connection. However, I argue that, with Locke's adjusted knowledge criteria, certainty is not a necessary condition for knowledge. According to this horn, Locke's previous arguments, such as the Argument from Vividness and the Argument from Conformity, become strong inductive arguments. In addition, Locke adopts pragmatic arguments against unbridled skepticism. For instance, note the pragmatic quality of the following inductive argument concerning the relationship between his ideas-of-things and the things-in-themselves:
This argument states: even if we don't know that the world-as-it-is corresponds to our sense-data, we have enough evidence that the world-as-it-is constantly produces the same sense-data, under the same circumstances, that we may act as though there is uniformity. Much of Locke's causal theory of perception depends on ╬insensible particles' whose effects bear no resemblance to the things that cause them. In answer to problems such as these, Locke states:
This is, once again, a highly pragmatic argument against the kind of skeptical concerns, that Jonathan Bennett raises. Locke's arguments accuse skeptics of taking skepticism too far. It is one thing to doubt; but, if we must doubt all the evidence of our senses, if uncertainty is the overriding principle of our theory, then it seems we have taken the exercise too far. The skeptic's dependence on certainty can become an obstacle in his acquisition of knowledge. Locke is asserting that the combined strength of his inductive arguments with the addition of an effective pragmatic argument against skepticism is enough for any reasonable person to attest that they have knowledge of external objects. The skeptic may object that this formulation merely sidesteps the issue (on the one horn Locke defines his way into certainty and, on the other horn he asserts that certainty isn't necessary for knowledge) nevertheless, this objection would miss the pragmatic element of Locke's theory. Do Locke's ideas constitute a ╬veil of perception' between our minds and reality? The answer to this question depends on the criteria you adopt: