Simple Ideas as the Foundation of Knowledge

John Locke is often credited with beginning the empiricist movement in philosophy, which deems experience as the sole means of acquiring knowledge. In his Essay Concerning Human Understanding, Locke attempts to lay the foundation of human knowledge, beginning with the origin of ideas. Locke posits that all ideas about the universe, objects, people, or even God can be traced back to simple ideas. Ideas like God or cars or rocks are merely amalgamations of simple ideas, which Locke calls complex ideas. Simple ideas, therefore, necessarily exist in order to form complex ideas. Thus, simple ideas are the ultimate sources of human knowledge for Locke.

Locke's essay begins with the nature of ideas and their origins in the human mind. What does Locke mean by ideas? Ideas, according to Locke, are the objects of thinking. Black, white, hard, soft, fast, slow, tired, awake, sweet, salty, dog, cat, and football are ideas. Ideas qualify objects. In other words, objects and ideas are inexorably linked; there cannot be an idea without an object with which to form the idea. Similarly, there cannot be ideas without thoughts to form them. In this account of ideas, Locke naively assumes there is an external world full of objects. Locke does not attempt to explain or prove that objects in the world exist, but rather he presupposes the objective existence of objects in order to base his concept of ideas on them. Ideas, Locke argues, originate from one source: experience. Our minds at birth are void of all ideas, like a blank piece of paper without words. Lock uses this analogy of a "tabula rasa" to demonstrate his contention that innate ideas do not exist. Therefore, the only way to acquire ideas is through experience, either from sensation or from reflection. Ideas of sensation refer to ideas which arise immediately from our sensory organs. Ideas of reflection, on the other hand, refer to "operations of the mind" taking notice of its own ideas; for instance, perceiving, willing, knowing, reasoning, and doubting. Locke further divides ideas into two categories: simple and complex. Simple ideas are those ideas which contain "one uniform appearance, or conception in the mind, and as we discovered earlier, ideas of sensation refer exclusively to the realm of the sensory organs. Thus, our eyes, ears, nose, tongue, and skin are the necessary components of sensation. Locke asserts that objects have qualities, or abilities to produce a sensation in our sense organs. For example, an apple possesses a quality that causes us to see the color red. Locke makes the claim that some qualities are actually contained in the object, while other qualities are not. Locke calls those qualities of objects actually present in the objects themselves primary qualities. Primary qualities are inseparable from the object; thus, ideas of extension, figure, solidity, rest, and motion are primary qualities. Primary qualities are accurate depictions or representations of the objects themselves. Locke describes secondary qualities in a converse fashion:

Such qualities, which in truth are nothing in the objects themselves, but powers to produce various sensations in us by their primary qualities, i.e., by the bulk, figure, texture, and motion of their insensible parts, as colors, sounds, tastes, etc., these I call secondary qualities. (II, 8, 10)

By this definition of secondary qualities, the operations of "insensible particles" characterized by the primary qualities produce the secondary qualities. Secondary qualities, therefore, have no objective existence. This effectively explains why we all have subjective experiences (what I may see as pink, others may see as magenta) when encountering various objects. Secondary qualities such as colors, sounds, tastes, and smells are merely reactions produced in our minds by the primary qualities. Thus, secondary qualities their primary counterparts, do not resemble the object. Locke may have been hinting at some major breakthroughs in science centuries after his death. Modern science tells us that colors, for instance, as we perceive them do not appear on the atomic level. The apparent color of an object is the result of the atoms in the object absorbing certain wavelengths of light and reflecting other wavelengths. Our philosophical apple ultimately has no "genuine" qualities other than being a hard, round, extended body. Accordingly, our ideas of sweet, red, or cold are nothing more than the mechanisms of the "insensible parts" which comprise the primary qualities of the apple.

To better explain simple ideas of sensation, Locke offers solidity as a prime example. Locke defines solidity as the force that "hinders the approach of two bodies when they are moving towards each other" (II, 4, 1). This definition of solidity appears rather troubling. Locke's definition of solidity seems to combine two simple ideas: that of mass and that of extension. We cannot qualify solidity without taking into account both mass and extension. Locke further explains solidity by differentiating it from hardness. A rather strange notion, Locke proposes water is a solid because it cannot be compressed, that is, its resistive force cannot be overcome. Water and a block of wood share the property that they cannot be compressed, even though conventional nomenclature would classify the former as soft and the latter as hard. According to Locke, "soft" and "hard" are merely relative definitions we assign to objects based on our own constitutions. Moreover, Locke claims that we cannot describe solidity or extension in terms of space. Solidity is defined as a body filling up space. The problem lies in the fact that space can be empty while extended and solid bodies must be composed of matter. Therefore, space cannot be a container for solid bodies because space is not composed of matter. Simple ideas of sensation play an important role in Locke's metaphysics, especially solidity, which takes on a new definition.

Simple ideas of reflection, on the other hand, refer to internal operations of the mind directed toward its own ideas. Locke divides simple ideas of reflection into two categories: perception or thinking and volition or willing. Ideas of reflection essentially refer to all faculties of the mind; Locke lists specifically those ideas of remembrance, discerning, reasoning, judging, knowledge, and faith. Ideas of reflection rely on ideas of sensation. Thus, for instance, I can discern the object I am looking at is indeed an apple after gathering the simple ideas of red, round, sweet, shiny, etc. My discerning or recognition of the apple as an apple is based only upon my sensory observations of the apple. I cannot recognize the apple as an apple without looking at it, tasting it, or touching it. How does the mind manipulate simple ideas to create complex ideas? Norman Melchert's explanation concerning the connection between simple ideas and mental faculties provides a clear answer. According to Melchert, simple ideas can be combined, compared, named, distinguished, or framed (378). In other words, we can put ideas together to form new ideas, we can discern the similarities or differences among ideas, we can categorize ideas by name, we can distinguish one idea from another, and we can combine simple ideas to form abstract ideas. In this manner, an infinite possibility of complex ideas can arise from a set of simple ideas. Locke intentionally or unintentionally subsumes two categories under ideas of reflection: emotions and mental activities. Mental activities, such as willing, often come from emotions. Mental activities describe memory, recognition, doubting, etc. Emotions, on the other hand, such as desire, love, and anger, do not fit under the categories of the volition or the perception. Let us suppose I feel the desire (an emotion) to drink water because I am thirsty. Consequently, the cascade of events that lead to me drinking water involve the transposition of a single simple idea. Before I feel the desire to drink, I receive sensory input from my throat which produces in me the sensation of dryness - a simple idea of sensation. I then reason the dryness in my throat is thirst and feel the desire to quench this thirst (a simple idea of reflection in the form of emotions and mental activities). Evidently, simple ideas play a much more proactive role in knowledge in reflection as compared to sensation. Whereas simple ideas of sensation are often involuntary (we do not choose to smell to a foul odor), simple ideas of reflection require our awareness. The importance of awareness becomes evident in Locke's account of perception.

Locke's prime example of a simple idea of reflection is perception. Locke defines perception as "that sort of operation in the mind...wherein the mind is active; where it, with some degree of voluntary attention, considers anything" (II, 9, 1). As mentioned earlier, Locke emphasizes the conscious, voluntary aspect of human cognition which he calls perception. Locke's claim is that perception must be restricted to those mental events of which we are aware. Accordingly, we can distinguish among subconscious and conscious perceptions. If I touch a hot stove and the nerves in my finger do not send a signal to my brain, then according to Locke I do not experience perception. This scenario represents the kind of subconscious or unconscious perceptions that Locke does not feel exemplifies actual perception. On the other hand, when I touch the hot stove and the nerve endings in my finger send signals to my brain alerting me of the intense heat, I will have felt actual perception. Garth Kemerling raises an interesting point concerning our ability to selectively perceive just a portion of the seemingly ubiquitous stimuli in the world:

Although we are almost constantly bombarded by physical stimuli-any one of which will, in the ordinary course of things, produce in our minds a particular sensory idea-we never perceive all of them and sometimes exercise deliberate control over which ones we do perceive. (Kemerling)

Kemerling here furthers Locke's emphasis on attentiveness in perception by claiming we may actually control and filter out certain perceptions. For example, when we enter a noisy room, the noise is initially intense and perhaps overwhelming. Ten minutes later, the intensity of the noise seems to decrease and we almost entirely forget about it. This phenomenon appeals to our mind's ability to habituate to certain stimuli and limit our perceptive abilities at least temporarily for our own benefit. Since Locke differentiates between brain events (receiving input from the sensory organs) and mental events (doubting or judging), we can say he is somewhat of a dualist. Descartes originally attempted to separate the thinking mind from the sensing body. Locke accomplishes this goal by making the very distinction between ideas of sensation and ideas of reflection. Ideas of sensation refer to the immediate sensory reactions only. Locke, however, does not explain the causal interaction between the mind and body, that is, how the brain translates the input from the sense organs into our ideas of reflection. Again we must refer to the apple. We detect red, shiny, round, and sweet from our faculties of sensation. From sensation alone we cannot possible know an apple is an apple. It is through our faculties of reflection that we perceive the idea of an apple from the ideas of red, shiny, round, and sweet. Ultimately, the reflection provides the pathway for which we can from complex ideas.

So what does all this mean for knowledge? First, Locke tells us that all knowledge is dependent on simple ideas. Without simple ideas, there is no knowledge. Complex ideas, which comprise our knowledge, must necessarily come from simple ideas. However, all we can possibly know is limited by the simple ideas, which in turn are limited by the objects in the world. Therefore, every idea in our mind must have its roots in the world in which we live. Furthermore, Locke claims that we as sensible humans are limited to the sensible realm as a result of our constitutions, or our physiological compositions. Because we only have five senses, Locke argues, we cannot conceive of any qualities in bodies that require a sixth sense or seventh sense or a ninetieth sense. That which escapes our olfactory, auditory, visual, tactile, and gustatory abilities is in effect inconceivable to us as humans. The third claim Locke makes is that we can abstract complex ideas from simple ones, imagining for instance, the idea of a zebra without stripes or a unicorn because we can put together the simple ideas of horns, horses, and zebras any way we like. This process of framing abstract ideas effectively provides us with our creative and imaginative abilities. Second, Locke is denying the objective existence of the secondary qualities of objects. Apples are not really sweet. Lemons are not really yellow. Though valid, this argument reduces the objective existence of objects to mechanical interactions of invisible particles. Locke effectively converts the colorful, noisy, diverse world into a colorless, silent, "wire-frame" structure of the world which lies beneath our sensory perception. Further still, Locke criticizes the Rationalists who pontificate over the possibility of a mind-independent reality. Locke already said that all we can possibly know is limited to what we can sense. Consequently, the possibility of an objective, mind-independent reality contradicts the very basis of our knowledge (that is, simple ideas, which must arrive from sensory experience) according to Locke. Since all we can possibly know is limited to the sensible objects in the world and the complex ideas which arise thereof, ultimately we cannot know anything else.

Knowledge, according to Locke, seems to be a like a tree whose roots are grounded in the simple ideas. Locke's argument is highly convincing, yet I must raise some objections. One objection to Locke's account of knowledge can be the fact that the idea of God is innate. Locke can defend his philosophy by claiming the concept of God is based upon the simple ideas. By examining the perfect harmony of the world using our senses, we can assume there is a perfect Creator who created this world. What about Descartes' claim that geometry and mathematics are innate ideas? Locke can only defend himself by claiming that knowledge of numbers and shapes arise from simple ideas of sensation. Locke could explain how the complex idea of a hexagon, which combines the simple idea of a line taken six times, arises from observing the simple idea of a single line. I must admit, however, Locke places a lot of faith in human cognition. It seems implausible to imagine a person constructing all the geometrical figures we commonly use in mathematics by observing one line only and abstracting the arrangements. The idea that time is innate can also be refuted. To support Locke's claim, I will imagine a person who lacks any sensory capabilities and has been isolated from all human contact. This person only has a consciousness, but no perceptions (much like a "brain dead" person in the medical sense). I believe it is impossible for this person to have any thoughts without sensing any objects. Therefore, this person cannot form the idea of time without a single thought. I must also discuss the strange implications of the secondary qualities. Locke is denying that perception comes from the object directly. I shall use the example of perceiving a shoe. Locke will argue that it is the secondary qualities of the shoe, such as its color and texture, which we perceive instead of the shoe itself. Kant's metaphysics addresses this peculiarity well. Kant would say that all objects have appearances that are actually part of the object. Thus, a banana really is yellow and sweet, even though we may perceive the banana in different subjective ways. There is, according to Kant, a human objectivity. Kant would say that it is nonsensical to talk about primary qualities of objects when only the appearances of the objects (the secondary qualities) are readily available to us. I will admit that Locke's account of perception is extremely strong. He effectively refutes unconscious perceptions because perceptions must be defined in terms of awareness and consciousness. Locke's account of reality grounds all knowledge in simple ideas, especially those of sensation. Ultimately, simple ideas are crucial aspects in human knowledge because without them, there is nothing.

Works Cited

Kemerling, Garth. "A Guide to John Locke's Essay Concerning Human Understanding." 27 Oct. 2001. 22 Apr. 2006 .

Locke, John. "An Essay Concerning Human Understanding." Modern Philosophy. Comp. Forrest E. Baird and Walter Kaufmann. New Jersey: Prentice Hall, 2003. 173-240.

Melchert, Norman. The Great Conversation. Vol. II. New York: Oxford UP, 2002. 375-379.