OPAR 2.1: The Validity of Sense Perception

Short Summary:

As the starting point of all consciousness and all cognition, sense perception is necessarily valid. The validity of the senses is an axiom and is outside the boundaries of proof. Arguments made against the validity of the senses typically misconstrue the role of the senses and incorrectly blame sense perception for failures of reasoning. Regardless of their form or limitations, the senses convey facts of reality and are therefore valid.

And now for a transition from metaphysics to epistemology.

Metaphysics, which has been the subject of the first five posts in this series, is essentially just the identification of the fact of existence along with the corollaries of that fact (according to Objectivism). Weirdly, the word metaphysics has a confusing etymology and does not accurately connote its subject matter. As the fundamental branch of philosophy, metaphysics is said to have arisen from Aristotle, who never once actually used the term himself. Rather, Aristotle referred to his writings on metaphysical subjects as first philosophy, focusing on three key subjects: being as such, first causes, and “that which does not change.” The term metaphysics emerged after Aristotle died, when his editor labeled his writings on first philosophy with the words, “Ta meta ta phusika,” or, “the after the physicals.” This label was either meant to indicate that the works were supposed to be read after Aristotle’s works on physics/nature, or that the books had been placed on the shelf after Aristotle’s writings on physics/nature. Regardless, centuries later, a group of Latin scholars misinterpreted Aristotle’s editor’s label as meaning, “the science of the world beyond nature.” This label managed to stick and went on to spark widespread misinterpretation of the term metaphysics. Many believe that the subject of metaphysics denotes the philosophical study of the immaterial, and this mistaken interpretation of the term remains popular to this day. But first philosophy, as originally studied by Aristotle, never should have been labeled as “the philosophical study of that which is beyond nature.” Metaphysics, for Aristotle and many others, is the philosophical identification of the fact of existence and its corollaries.

Epistemology, the subject upon which these next twenty-two blog posts will be focused, is named much more aptly than metaphysics. Epistemology is the branch of philosophy that studies the nature and means of knowledge. The word derives from two Greek words: episteme, meaning, “knowledge,” and logos, meaning, “reasoned discourse” or the scientific study of a particular subject. Commonly, the word knowledge is understood to mean an awareness or understanding of facts, which are verifiable actualities of reality.

The field of epistemology is based on the premise that not every random idea counts as knowledge and that human beings can acquire knowledge only if very specific processes are followed. Epistemology studies questions such as: what is the proper method for acquiring knowledge? Where does knowledge come from, and how can it be verified? Are some truths of existence unknowable? What does it mean to say that someone knows, or fails to know, something? In this wild and complex universe, how can anyone claim that any truth is a verifiable fact of reality? Is it possible to be one-hundred percent certain of any fact? If so, what are the limits of certainty?

In the second chapter of Objectivism: The Philosophy of Ayn Rand, Leonard Peikoff moves on from metaphysics to what he calls “the anteroom of epistemology” (OPAR, 39), a discussion of sense perception and volition. Before diving in, however, Peikoff lays out three facts upon which Objectivist epistemology is based. These facts are: 1) knowledge is knowledge of reality, 2) existence has primacy over consciousness, and 3) human consciousness, being conceptual in nature, is fallible and requires a method (37-38). Objectivist epistemology is based on the premise that a method of cognition must be discovered in order for a fallible human consciousness to validate conclusions and distinguish truth from falsehood. Because there can be no knowledge of reality apart from sense experience, and because conceptual understanding is volitional rather than automatic, a study of sense perception and volition are necessary prerequisites to any study of knowledge itself, writes Peikoff (38-39). And so, here we find ourselves in chapter two of OPAR. Peikoff begins his chapter on pre-epistemology at the beginning, at the starting point of all consciousness and all cognition: with sense perception.

Is sense perception valid?

According to Objectivism, sense perception is necessarily valid. Peikoff opens his discussion by claiming that the validity of the senses lies outside the boundaries of the burden of proof. Proof is the reduction of an idea back to the evidence of the senses. You cannot reduce the data provided by the senses any further than to itself. Because the evidence of the senses is a precondition of any proof, its validity cannot be justified in the same way you would prove, for example, that it is wrong to murder someone or that climate change is real. Sensory data is relied upon for all cognition and all concepts, and thus, the validity of the senses has to be justified in some way other than through reducing to antecedent knowledge.

Because the validity of the senses lies outside the boundaries of proof and is the foundation of all knowledge, the validity of the senses is an axiom (not its own independent axiom, but rather, a corollary of Rand’s axiom of consciousness). It is only because we have senses that we know we are conscious—we see, hear, smell, taste, or touch something that exists. Consciousness is an awareness of that which is. If we are aware of that which is, then our means of awareness are a means of awareness. Peikoff seems to be arguing that if our senses do, in fact, make us aware of something that exists, then they are valid (correct, effective, relevant, meaningful, or sound). If the senses are not valid (i.e., are not an effective means of being aware of that which exists), then consciousness cannot be said to exist. Peikoff writes, “One cannot affirm consciousness while denying its primary form, which makes all others possible” (39). In other words, one cannot claim to be conscious (aware of existence) while also claiming that one’s means of awareness do not provide an awareness of existence. If consciousness exists, then the senses are necessarily valid.

Since knowledge, for Objectivism, is knowledge of reality, denying the validity of the senses means denying all cognition. Peikoff writes, “If the senses are not valid, neither are any concepts” (39). This includes the concept being used to attack the senses, the concept that the senses are invalid. Sense data, according to Objectivism, is the foundation of all knowledge and all concepts. Therefore, one cannot use concepts, which derive from sensory data, to disprove the validity of sensory data.

Rather than focus his justification on trying to prove a fact that is self-evident, axiomatic, and un-provable, Peikoff’s discussion of the validity of the senses focuses instead on disproving the opposition. Peikoff writes, “the purpose of philosophical discussion of the senses is not to derive their validity from any kind of antecedent knowledge, but to define their exact function in human cognition and thereby to sweep away the objections raised against them by a long line of philosophers. The purpose is not to argue for the testimony of our eyes and ears, but to remove the groundless doubts about these organs that have accumulated through the centuries” (39). He does this by defining sensory experience, refuting several arguments made against the validity of the senses by other philosophers, and defining the precise function of the senses.

What is sensory experience? Peikoff writes that “sensory experience is a form of awareness produced by physical entities (the external stimuli) acting on physical instrumentalities (the sense organs), which respond automatically, as a link in a causally determined chain. Obeying inexorable natural laws, the organs transmit a message to the nervous system and the brain” (39-40). Sensation is different from other forms of awareness like introspection or conceptualization because sensation is totally automatic. There is no choice, creativity, or volition involved in the experience of sensing. Rather, our sense organs merely react when acted upon by the external stimuli of the universe. Just like every other entity, our sense organs are subject to the law of causality and can only act and react according to what their physical characteristics allow. Peikoff writes that “such organs have no power of choice, no power to invent, distort, or deceive. They do not respond to a zero, only to a something, something real, some existential object which acts on them.” (40). If a sense organ reacts to a stimulation and transmits a message to the brain, it is because something exists out there that is acting on the senses. The senses are not proactive; they do not edit or create. The senses are reactive. They are messengers of the actions of external stimuli. All that the senses do is make us aware that some sort of things exist. They do not communicate what exactly the things are (that is the job of reason), but merely that they are (40).

Contrary to what philosophers have claimed, many mistakes that are blamed upon the senses are a result of human conceptual error and are not the fault of the senses themselves. For example, “If a boy sees a jolly bearded man in a red suit and infers that Santa Claus has come down from the North Pole, his senses have made no error; it is his conclusion that is mistaken” (40). The boy’s senses are not at fault; they correctly transmitted the smiling face, the large beard, and the red suit. The mistake was made when the boy extrapolated from sense data to an incorrect conclusion. His reasoning failed him—not his senses. Another example can be found in the famous story of the blind men and the elephant. In this story, a group of blind men each put a hand on a different part of an elephant. One man touches the elephant’s tusk, another touches the elephant’s leg, another its trunk, another its side. Based on sensory data, each man concludes that the elephant is something different. The first blind man concludes that the elephant is a spear, the second concludes it is a tree trunk, the third a snake, and the fourth a wall. In this story, as in the story of the boy thinking he sees Santa Claus, it is not each blind man’s sense of touch that fails him, but rather his conclusion. In this way, many supposed failures of the senses are in fact just failures of reasoning.

Neither do so-called sensory illusions disprove the validity of the senses. Peikoff writes, “A so-called sensory illusion, such as a stick in water appearing bent, is not a perceptual error. In Ayn Rand’s view, it is a testament to the reliability of the senses” (40). In the case of the stick and the water, the senses are simply responding to the full-context of facts, including the fact that light travels more slowly through water than it travels through air, which is what causes the stick to appear bent. The senses do not censor their message to the brain in order to make the universe easier for the human mind to understand; all they do is transmit all of the data automatically and without distortion or edits. This is why Rand and Peikoff claim that a stick appearing bent in water is actually evidence of the reliability of the senses rather than of their failure. Peikoff writes, “If a casual observer were to conclude that the stick actually bends in water, such a snap judgment would be a failure on the conceptual level, a failure of thought, not of perception. To criticize the senses for it is tantamount to criticizing them for their power, for their ability to give us evidence not of isolated fragments, but of total” (40). By defining the specific role that sensory data plays in the cognitive process, Peikoff refutes this common argument made against the validity of the senses.

What is the precise function of the senses? According to Peikoff, the role of the senses is essentially to synopsize an enormous amount of data about the universe into a digestible summary comprised of a few simple sensations received by our conscious mind. Each sensation is the tiny tip of an enormous iceberg. The sensations we experience are condensed clues about complex stuff that exists in reality. For example, “we perceive a bunch of roses…as red, cool, fragrant, and yielding to the touch. Such sensations are not causeless. They are produced by a complex body of physico-chemical facts, including the lengths of the light waves the roses reflect and absorb, the thermal conductivity of the petals, the chemical makeup of their molecules, and the type of bonding between them; these facts in turn reflect the underlying atomic structures, their electronic and nuclear features, and many other aspects. Our sensations do not, of course, identify any of these facts, but they do constitute our first form of grasping them and our first lead to their later scientific discovery” (41). Essentially, the function of the senses is to provide a starting point for the cognitive process. Once we have some initial evidence, we can organize it, compare, and classify in order to develop further knowledge and move up to the conceptual level, where scientific theories and formulations are possible.

Peikoff ends his discussion of the validity of the senses by explaining the role that sensory form plays in sense perception. The type of sense organs we possess prescribes the manner in which we perceive objects—with a smell, a taste, a color, etc. If our senses were of a different type, for example, if we didn’t have eyes and ears and instead had fleebobs and zigleeduds, we would presumably perceive reality in an entirely different way.

Does sensory form distort or control reality? Do the sense organs confine a person to his own universe, totally unique from the universe of other beings possessing different sense organs? Peikoff argues no. The form of one’s senses has absolutely no impact on an individual’s ability to accurately perceive reality. Difference in sensory form is a difference in form only; not content (42). If the role of the senses is to give a conscious mind a starting point from which to gain knowledge of the universe, then as long as a person can grasp similarities and differences between entities that exist, the type of sensory experience that is used to gather the data is irrelevant. This is why philosophers who attack the senses on the basis of form are wrong, according to Objectivism. Peikoff writes, “Species with different sense organs gain from perception different kinds (and/or amounts) of evidence. But assuming that a species has organs capable of the requisite range of discrimination and the mind to interpret what it perceives, such differences in sensory evidence are merely different starting points leading to the same ultimate conclusions” (43). No form of perception is any more or less valid than our own. Every type of sense organ condenses information on a certain scale, perceives some aspects of reality more directly than others, and is incapable of immediately perceiving other facts that are too large or too small to be registered. But no matter how big or small a being’s sense organs are, there is still only one universe. It does not matter from which data you start. All sensory data offers clues about the same fundamental reality.

What it comes down to is that the facts that the senses convey are indeed facts, no matter how limited in scale or form. The data transmitted by the senses leads to all further knowledge. The validity of the senses is axiomatic, self-evident, and unassailable. Can any honest philosopher, after considering Peikoff’s arguments, find sincere cause to doubt or deride the validity of sense perception?

Questions and Concerns:

  • Why have so many philosophers unfairly denigrated the senses and cast doubt on their reliability? If the validity of the senses is so self-evident, why the barrage of criticism from philosophers of all creeds?

Level of Difficulty: Low

Mystery Number: 90

Works Cited:

1. Peikoff, Leonard. Objectivism: The Philosophy of Ayn Rand (New York: Dutton, 1991). New York: Meridian, 1993.

This cute dog never questions the validity of his senses. Why should you?

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