can’t see the forest

Rationalism and Empiricism

Posted in empiricism, knowledge, philosophy, rationalism, Science by Curtis on 10/7/07

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There is a driving force behind a mystery that we cannot understand, and it includes more than reason alone . . .who knows what form the forward momentum of life will take in the time ahead or what use it will make of our anxious searching? The most that any one of us can seem to do is to fashion something—an object or ourselves—and drop it into the confusion, make an offering of it, so to speak, to the life force.

-Ernest Becker
The Denial of Death, 1973
Pulitzer Prize for Non-fiction, 1974 (posth.)

“To them, I said, the truth would be literally nothing but the shadows of the images . . . and if he is compelled to look straight at the light, will he not have a pain in his eyes which will make him turn away to take refuge in the objects of vision which he can see? . . . When he approaches the light his eyes will be dazzled, and he will not be able to see anything at all of what are now called realities.”

-Plato

The Republic

PROJECT -ISM, No. 2.

Plato’s rationalism, in essence, is embodied by his Allegory of the Cave from which the quote above is taken. In The Republic, Socrates asks his audience to imagine several men held captive deep inside a cave, chained tightly to a wall so that they can only face forward. Atop this wall behind them, he said, we should imagine a blazing fire; and when the captors of these men pass before the fire, their shadows are projected onto the wall in front of the unlucky inmates. Socrates points out that, eventually, the prisoners would come to regard the shadows as the true forms of that which exists—as things unto themselves and not as shadows. Then he asks us to imagine that one of the prisoners escapes into the sunlight and beholds, for the first time, the dazzlingly illuminated forms of the greater and more majestic cosmic reality. This splendid but laborious emergence was Plato’s way of constructing a metaphor for the progression from a commonsense, practical, but static and incomplete worldview based on experience (represented by the shadows) into a more dynamic, circumspect, and realistic view of the Universe obtainable only through reason (which is represented, of course, by the sunlight).

Ernest Becker’s The Denial of Death is really not as austere as the title might suggest; in fact, I would venture the statement that it is, to modern sensibilities, an indispensable volume for any student of psychology, sociology, anthropology, or philosophy. In this book, Becker lovingly dismantles Freud’s psychosexual motivational theories—which he regards as the noteworthy work of a great scientist, but discolored by Freud’s own neuroses and tendencies to perversion—and, enlisting the help of men such as Otto Rank and Norman O. Brown, replaces them with a picture of man as a uniquely rational animal constantly confronted with the knowledge of his own mortality. This “terror of death,” for Becker, is a much more tenable and constructive explanation for human motivation. One implication of Becker’s theory is that an overzealous devotion to rationalism (or, we might say conversely, an overzealous refutation of empiricism) is a tendency to be expected of mortal creatures wishing to escape the preponderance of empirical evidence for their irreversible and permanent mortality.

Encyclopédie Frontispiece The student of philosophy is typically presented with rationalism and empiricism as conflicting epistemological mores which have been unable to peaceably coexist throughout history. In reality, the two concepts are not mutually exclusive, and there has never been a philosopher who has wholeheartedly committed himself or herself to one or the other without exception of any kind. We retrospectively describe David Hume as an “empiricist” and René Descartes as a “rationalist,” and with good reason, but it must be recognized that these terms are more relativistic than categorical.

In this, the second part of Project -ism, I want to discuss the differences between rationalism and empiricism—the strengths and weaknesses of both—and also to divulge their inseparability and their complementary natures.


Epistemology can be defined as the study of knowledge—of what does and does not constitute it, and of its limits and usages. The implicit equivalence of knowledge and truth is an important part of the rationalist/empiricist conflict, as we shall quickly see; it also provides the key through which the issue is disentangled.

Rationalism as an epistemological approach dates back to the pre-Socratics and to Plato, who believed in the self-sufficiency of reason. For these philosophers, sensory information was often deceptive. Consider the apparent size of the moon: there is nothing about the appearance of the moon in the sky which would suggest, in and of itself, that the moon is any larger than a 25-cent piece. For the classical rationalist, one arrives only at the truth through the operation of reason upon sensory data. John Locke

Empiricism, in contrast, is the view that truths are arrived at only through the validation of rational belief through sensory experience. For the empiricist, there is no such thing as the ‘innate idea’ or a priori knowledge. All knowledge is derived from sensory data—otherwise, there is nothing to rationalize in the first place. No matter how self-evident a proposition might seem, the empiricist requires a concrete test against observations of the natural world in order to grant such a proposition the property of truth. British empiricism was founded in large measure upon the ideas of John Locke (pictured), who spoke of the mind as a tabula rasa—a ‘clean slate’ upon which experiences leave their marks. The word ‘empiricism’ is derived from the Greek εμπειρισμός (empeirismós), meaning, roughly, “experience.”At this point, it would be wise to say something of the concepts of a priori and a posteriori knowledge:

  • A priori knowledge is most commonly defined as knowledge that is the product of reason alone. As such, all statements which are a priori true are tautologies (self-evident propositions).
  • A posteriori knowledge is most commonly defined as knowledge that can only be gained through sensory experience.

As an example, Jerry Fodor once proposed the following: the statement “King George V reigned from 1910 to 1936″ is an example of a posteriori knowledge, because one can only gain this knowledge through experience—it is something of the external world which is learned; but the statement “If George V reigned at all, then he reigned for a while” is an example of a priori knowledge, because it is something that can be deduced rationally absent any supporting data.

A priori knowledge can be viewed as the product of deductive reasoning, while a posteriori knowledge is the fruit of inductive reasoning.

With the early modern philosophers, and specifically with Descartes, came a renaissance of the Pythagorean idea that mathematics represents a kind of a priori knowledge or pure reason. The British empiricist David Hume referred to a priori knowledge as ‘Relations of Ideas’ and to a posteriori knowledge as ‘Matters of Fact.’ Consider the following, from Section IV of his An Enquiry Concerning Human Understanding:

20. All the objects of human reason or enquiry may naturally be divided into two kinds, to wit, Relations of Ideas, and Matters of Fact. Of the first kind are the sciences of Geometry, Algebra, and Arithmetic; and in short, every affirmation which is either intuitively or demonstratively certain. . . Propositions of this kind are discoverable by the mere operation of thought, without dependence on what is anywhere existent in the Universe. Though there never were a circle or triangle in nature, the truths demonstrated by Euclid would for ever retain their certainty and evidence.

21. Matters of fact, which are the second objects of human reason, are not ascertained in the same manner; nor is our evidence of their truth, however great, of a like nature with the foregoing. The contrary of every matter of fact is still possible; because it can never imply a contradiction, and is conceived by the mind with the same facility and distinctness, as if ever so conformable to reality. That the sun will not rise tomorrow is no less intelligible a proposition . . . than the affirmation, that it will rise. . . It may, therefore, be a subject worthy of curiosity, to enquire what is the nature of that evidence which assures us of any real existence and matter of fact, beyond the present testimony of our senses, or the records of our memory.

Circle - Pi According to Hume, we can imagine, however extraordinarily unlikely we might suppose it to be, waking at 7 a.m. to find that it is still night-time, that our face of the Earth has not yet turned into the sunlight and that the stars are still twinkling in the midst of the great blackness; we cannot imagine a circle whose circumference is not equal to its diameter times the value π.

This is because the relationship between the radius or diameter and the circumference of the circle is part of the definition of a circle, and because the definition of a definition is a description which holds in all cases. Thus, we might encounter a thing in nature which would appear to the senses to be circular; but we could not say without precise measurements and calculations whether or not it actually were circular. The Earth, for example, is not spherical. It is roughly spherical. So, if we are to prove the truth of the statement “This is a circle” with reference to a particular object of scrutiny, we cannot do so without dividing its circumference by its diameter and obtaining an approximation of π, or some equivalent operation. Now, we could communicate with one another about an ostensibly circular object in a way that would be effective for most practical purposes, without ever finding the need to resort to such precision. But if we are to prove that the object is circular, we must show that it conforms to the preconceived definition. Thus, in a majority of like cases, we could well be speaking of something not necessarily circular as if it were, without any appreciable effect upon our experience, because the thing seems circular enough. Thus, for Hume, empirical observation and methodical comparison was the only path to absolute knowledge.

Immanuel Kant The great Immanuel Kant (pictured) credited Hume’s text with “awakening him from his slumber” and causing him to question the tenets of rationalist philosophy. In his Critique of Pure Reason, Kant attempted to bridge rationalism and empiricism, while refuting Hume’s premise that only the empirically testable is absolutely true. He largely agreed with Locke’s characterization of the mind as tabula rasa, admitting that there can be no knowledge without experience; but he disagreed that all knowledge must arise from experience, noting that, by the comparison of experiences, we gain valid information which is not the result of any particular experience. Kant attempted to define this as synthetic a priori knowledge, and argued that the axioms of geometry are examples of this kind of knowledge in that they logically follow from fundamental truths without having to be proven in relationship to some aspect of the external world, but that they can be empirically proven even though they did not arise from empirical observation. Wasting no time, Kant poses his ideas in considerable detail right at the outset of the right formidable Critique:

There can be no doubt that all our knowledge begins with experience. For how should our faculty of knowledge be awakened into action did not objects affecting our senses partly of themselves produce representations, partly arouse the activity of our understanding to compare these representations, and, by combining or separating them, work up the raw material of the sensible impressions into that knowledge of objects which is entitled experience? In the order of time, therefore, we have no knowledge antecedent to experience, and with experience all our knowledge begins. But though all our knowledge begins with experience, it does not follow that it all arises out of experience. . .

For it may well be that even our empirical knowledge is made up of what we receive through impressions and of what our own faculty of knowledge (sensible impressions serving merely as the occasion) supplies from itself. If our faculty of knowledge makes any such addition, it may be that we are not in a position to distinguish it from the raw material, until with long practice of attention we have become skilled in separating it. This, then, is a question which at least calls for closer examination, and does not allow any off-hand answer . . .

Kant arrived eventually at the idea which Schopenhauer wrote “produces a fundamental change in every mind that has grasped it” and which I formulated independently—and far less eloquently—in Dualism and Monism, Project -ism No. 1: that we cannot understand the world as something which exists in and of itself (Kant: das Ding-an-Sich) apart from our cognition of it.

We can see, then, that in the most general possible sense of the word ‘knowledge,’ both empirical induction and rational deduction are capable of producing knowledge. But does either type of knowledge represent the truth moreso than the other? If not, what is the purpose of any debate between rationalism and empiricism? Wittgenstein had something further to say of this in his Tractatus from the early 20th Century:

6.37 A necessity for one thing to happen because another has happened does not exist. There is only logical necessity.

6.371 At the basis of the whole modern view of the world lies the illusion that the so-called laws of nature are the explanations of natural phenomena.

6.372 So people stop short at natural laws as something unassailable, as did the ancients at God and Fate. And they are both right and wrong; but the ancients were clearer, in so far as they recognized one clear terminus, whereas the modern system makes it appear as though everything were explained.

Wittgenstein does not postulate that science and empiricism are useless. Indeed, modern medicine and numerous other technologies would seem to adequately demonstrate that, in terms of usefulness, science is far superior to supernatural mysticism. Wittgenstein’s argument is against knowledge as truth, and this argument is in line with his insistence that the greatest philosophical quandaries are, in essence, linguistic quandaries.

MicrochipLet us return to what Kant wrote: “For it may well be that even our empirical knowledge is made up of what we receive through impressions and of what our own faculty of knowledge supplies from itself.”

This is the skeleton of the model of the mind as a computer with I/O capabilities! Observe:

  1. What we receive through impressions – Data which is retrieved from the sensory organs, which function as input devices.
  2. What our own faculty of knowledge supplies from itself – Analytical data which is the output of the mind, which functions as a processor capable of modifying its own software.

Framed within this scaffolding, we begin to conceive of three things which are critical to understanding the complementary natures of empiricism and rationalism:

  1. All knowledge is rational by definition. Knowledge is analytical data which is the product of the processing of raw data or of other analytical data—this processing is what Kant describes as “what our own faculty of knowledge supplies from itself,” which is the process of rationalization.
  2. Empirical methods are required to determine the self-consistency of knowledge, and this property of consistency grants knowledge a character that cannot be imparted through rational activity alone. For instance, philosophers traditionally characterize the formula Cd as an a priori piece of knowledge defining the key formative properties of a circle. But only by drawing numerous circles, taking the appropriate measurements, and performing the necessary calculations can we show the consistency of this piece of knowledge.
  3. Self-consistency of knowledge does not equate to the consistency of knowledge with reality—ergo, there is no “absolute truth.” In order to show that our formula for the circumference of a circle were true in all cases, we would have to draw infinitely many circles. This is not something we are capable of doing, so we choose an arbitrary stopping point. But to state that 10,000 affirmations of the formula is equivalent to the affirmation of the formula in all cases is clearly fallacious. Thus the limitations of rational knowledge and empirical knowledge are intertwined inseparably. There is no truth, only degrees of demonstrable consistency for a given purpose—and that this purpose is in every case given is essential to any meaning that the knowledge might have.

We have said that all a priori knowledge not derived from experience must take the form of tautology, the self-evident proposition. For instance, from the formula C=πd, we can derive a priori the formula 1/2(C)=1/2(πd), but this formulation contains no new information. Likewise, we could show, most unempirically, that π=C/d; but this, also, is merely reiteration, or the manipulation of forms.Therefore, to my mind—and the point at which I depart from Kant and some others—those propositions which are a priori are, in fact, not knowledge. This is the danger of equating the a priori with rationalism and the a posteriori with empiricism, a false equation if ever there was one. Knowledge consists of rationalization, but knowledge based on extant analytical data does not constitute a priori knowledge any more than knowledge based on fresh empirical data. This appears to be a function of neuroarchitecture, of the way in which sensory data is mapped in the mind. We can rewrite our mental software, but we cannot rewrite the firmware or reconstruct the hardware.

Rationalism and empiricism are not competing methods, but necessarily complementary ones. The friction between them arises principally from Quixotic quests to demonstrate the supremacy of one over the other, when the more realistic perspective follows from the acknowledgement of the necessity and inherent inadequacies of each. The conception that either is more adequate than the other as a digging tool for truth has been, I hope, demonstrated to be nonsensical, since the concept of truth as constant and infinite is illusory.

To return to the Platonic Allegory of the Cave, we can see that the escaped prisoner cowering in the sunlight is better off than his enchained peers, but still bound by gravity and the confines of his own skull after all.

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6 Responses

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  1. riddlej said, on 10/8/07 at 2:20 pm

    I like your idea that empiricism imparts a character to knowledge that it cannot otherwise obtain from rationalization, i.e. proof.

    As for your thesis about empiricism and rationalism, I am not sure where I stand. As a lay philosopher, I think you have some good points. As a psychologist of special needs children, however, I believe that this field has something to add to the philosophical discussion, namely experience (or, what is /real/).

    What is /real/ is that children whose brains are not functioning normally, illustrate the connection but nuances of rationally and experientially obtained knowledge. For the autistic or Asperger’s child, details are gained through sensory apperception at an extraordinary pace and capacity. Dictionaries can be memorized, animal taxonomies internalized, and details of math, science, and literature absorbed with amazing facility.

    However, the “higher” rationalization process of comprehending, synthesizing, and evaluating are almost non-existent. Their brains have little capacity to deduce, apply, generalize, moralize, or generally make sense of the data they are getting. Something as simple as, “Which do you like better? The homo habilis or homo erectus?” or “Which costs more, a 54-Chevy or a 63-Corvette?” cannot be answered. The empirical functions of the brain, if you will, are far surpassing the rational functions of the brain.

    Something similar occurs in people with language disabilities (where individual words are comprehended, but sentences or context is not), and patients with Alzheimers (where details of a face are perceived, but recognition of who that face is, is not).

    Studies of Downs Syndrome children, however, sometimes reveal the opposite problem. While these children have a capacity for reading, learning, and education that other disabled children may not have, they often lose sight of the details when asked about them. Their analytical abilities may not work, while the “big-picture” comprehension skills, or basic logic skills, may. For example, a Downs Syndrome child may be able to understand and demonstrate patriotism, allegiance, or love of family/friends. When asked “why?”, they may be able to explain accurately their reasoning. But “small-picture” knowledge may always evade them, even simple calculations, historical facts, or names of biological phenomena. They might misjudge the lengths of lines, or other apparently obvious mathematical demonstrations. They simply cannot hold the details that the autistic or Asperger’s child picks up so easily.

    So this causes me to stop and think about the nature of empiricism and rationalism that you are talking about. I’d like to say that they are indeed two complementary aspects of knowledge. The same as perhaps saying “2×2=4″ where “2×2″ is the parts (empiricism) and “=4″ is the whole (rationalism). You can’t have one without the other, and the senses accomodate, or prove, the knowledge gained by logic. But clearly the observations in the psychology of the brain also indicate that there is a real difference in processing required, and that they can, in some significant way, be disentangled from one another.

  2. Curtis said, on 10/12/07 at 4:29 pm

    These are some excellent observations and it is wonderful to have a psychological perspective. Thanks!

    It seems somewhat intuitive that epistemology is centered around the faculties of cognitive psychology, and for that reason, I think it is quite productive to see what certain cognitive ‘disorders’ such as autism spectrum and Alzheimer’s can reveal about the nature of knowledge.

    I agree that we can show that there are different mechanisms involved in memorization and processing. So it is that certain autistic persons have the ability to play back extraordinarily complex pieces of music at first hearing without having any explicable knowledge of what they are doing. But I wonder if this necessarily means that they are not capable of the cognition of rationalization, or just that they are incapable of expressing or communicating that knowledge?

    It’s evident that empirical and rational activity are both necessary to what we’d call ‘knowledge’ very generally. But, when we begin to examine neuroprocesses, it does become possible to untangle the two for some purposes.

  3. I said, on 10/25/07 at 12:51 am

    i am so cool

  4. janmetra said, on 11/14/07 at 7:54 pm

    this helped me so much in my doctoral class on philosophy.. at this point my mind was so overwhelmed with information..this made it very simple and plain for me! this was awesome!

  5. [...] Rationalism and Empiricism (epistemology) [...]

  6. Used Corvette said, on 10/12/08 at 9:04 am

    I bookmarked your blog, thanks for sharing this very interesting article


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