Ridling Zaine. Philosophy: Then and Now. A look back at 26 centuries of thought

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Ridling, Philosophy Then and Now: A Look Back at 26 Centuries of Thought

878

of human knowledge. After showing that all human knowledge depended

upon thought or reason, not sensation or imagination, he then proceeded to

prove to his own satisfaction that God exists; that the criterion for knowledge

is clearness and distinctness; that mind is more easily known than body; that

the essence of matter is extension; and that most of his former beliefs are true.

Few of these proofs convinced many people in the form in which

Descartes presented them. One major problem is what has come to be known

as the Cartesian circle. In order to escape from the possibility that an evil

genius is deluding him about everything he believes, Descartes proves that

God exists. He then argues that clearness and distinctness is the criterion for

all knowledge because God does not deceive man. But, since this criterion is

arrived at only after the existence of God has been proven, he cannot appeal to

this criterion when he presents his proof for the existence of God; hence he

cannot know that his proof is cogent.

John Locke

An Essay Concerning Human Understanding by John Locke (1632-

1704) is often taken to be the first major empiricist work. Book I discusses

innate ideas in order to deny that there are any; Book II discusses various

genuine kinds of ideas; Book III discusses language with an emphasis on the

meaning of words; and Book IV discusses knowledge and related cognitive

states and processes.

Innate ideas are ideas that humans are born with. Rationalist

philosophers, like Descartes and Gottfried Wilhelm Leibniz (1646-1716),

thought that there have to be such ideas in order to explain the existence of

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some of the ideas which humans have. One argument for innate ideas is that,

while the ideas of blue, dog, and large, for example, can be explained as the

result of certain sense impressions, other ideas seem unable to be attributed to

sensation. Numbers, for example, seem to be outside the realm of sensation.

Another argument is that some principles are accepted by all human beings,

as, for example, the principle that out of nothing nothing comes. Locke did not

think either of these arguments had any force. He held that all ideas can be

explained in terms of sensation, and he set as one of his projects the task of

providing such an explanation. Instead of directly attacking the hypothesis of

innate ideas, Locke’s strategy was to refute it by showing that it is otiose and

hence dispensable.

In Book II of the Essay Locke supposes the mind to be like a blank sheet

of paper that is to be filled with writing. How does the paper come to be

filled? “To this I answer, in one word,” says Locke, “Experience.” He divides

experience into two types: observation of external objects and observation of

the internal operations of the mind.

Observation of external objects is another description for sensation.

Observation of the internal operations of the mind does not have its own word

in ordinary language, and Locke stipulated “reflection” to designate it,

because people arrive at ideas by reflecting on the operations of their own

minds. Examples of reflection are perceiving, thinking, doubting, believing,

reasoning, knowing, and willing.

An idea is anything that the mind “perceives in itself, or is the immediate

object of perception.” Qualities are the powers that objects have to cause

ideas. Many words have dual senses. The word red, for example, might mean

either the idea of red in the mind or the quality in a body that causes the idea

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of red in the mind. Some qualities are primary in the sense that all bodies have

them. Solidity, extension, figure, and mobility are primary qualities.

Secondary qualities are those powers that, in virtue of the primary qualities,

cause the sensations of sound, color, odour, and taste. Locke’s view is that the

phenomenal redness of a fire engine is not in the fire engine itself, nor is the

phenomenal sweet smell of a rose in the flower itself. Rather, certain

configurations of the primary qualities cause phenomena such as the

appearance of red or the taste of sweetness, and in virtue of these

configurations the object itself is said to have the quality of redness or

sweetness. But there is no resemblance between the idea in the mind

(phenomenon) and the secondary quality that causes it. Locke claims, without

justification, as George Berkeley was later to argue, that there is, however, a

resemblance between primary qualities and the ideas of them. (Locke

distinguishes a third sort of quality, e.g., the power of fire to produce a new

color or consistency in wax or clay, but he makes nothing of it.)

Although Locke along with most distinguished modern philosophers

repudiated Aristotelianism and the Scholasticism to which it gave rise, a

doctrine of abstraction survives in his philosophy. Abstraction occurs when

“ideas taken from particular beings become general representatives of all of

the same kind.” That is, to abstract is to ignore the particular circumstances of

time and place and to use an idea to represent all things of a certain kind.

In Book IV Locke finally defines knowledge as “the perception of the

connexion of and agreement, or disagreement and repugnancy of any of our

ideas.” He also distinguishes several degrees of knowledge. The first is

knowledge in which the mind “perceives the agreement or disagreement of

two ideas immediately by themselves, without the intervention of any other,”

which he calls “intuitive knowledge.” His first examples are such analytic

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propositions as “white is not black,” “a circle is not a triangle,” and “three are

more than two.” But later he says, “The knowledge of our own being we have

by intuition.” Relying on the metaphor of light as Augustine and others had,

Locke says of this knowledge that “the mind is presently filled with the clear

light of it. It is on this intuition that depends all the certainty and evidence of

all our knowledge.”

The second degree of knowledge occurs when “the mind perceives the

agreement or disagreement of... ideas, but not immediately.” Some mediating

idea makes it possible to see the connection between two other ideas. Proofs

are things that show the mediating connections between ideas, and a clear and

plain proof is a demonstration. Demonstrative knowledge is certain but not as

evident as intuitive knowledge, says Locke, because it requires effort and

attention to go through the steps needed to recognize the certainty of the

conclusion.

A third degree of knowledge, “sensitive knowledge,” approximates to

what Duns Scotus and Ockham called “intuitive cognition,” namely, the

perception of “the particular existence of finite beings without us.” Unlike

medieval intuitive cognition, Locke’s sensitive knowledge is less certain than

his intuitive or demonstrative knowledge.

Beneath knowledge is probability, which is the appearance of agreement

or disagreement of ideas with each other. Etymologically, probability is a

likeliness to be true, and it guides in matters “whereof we have no certainty.”

Locke suggests that probability rests upon the testimony of others and, like

knowledge, comes in degrees, which depend upon the likely veracity of the

sources of the proposition. The highest degree of probability attaches to

propositions endorsed by the general consent of all people in all ages. Locke

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may have in mind the virtually general consent of his contemporaries in the

proposition that God exists. But he explicitly mentioned beliefs about causal

relations, which are not perceived but inferred. To argue from such beliefs is

called “an argument from the nature of things.” The next degree of probability

or assurance in probable propositions attaches to matters that hold not

universally but for the most part, such as that persons prefer their own private

advantage to the public good. This sort of proposition is typically derived

from history. The next degree of probability or assurance attaches to claims

about specific facts; for example, that a man named Julius Caesar lived a long

time ago. Problems arise when testimonies conflict, as they often do, but there

is no simple rule or set of rules that instructs one how to resolve such

controversies.

In addition to these probabilities, all of which concern particular matters

of fact, there are also probabilities about things that are not within the power

of the senses. The existence, nature, and operation of angels, devils, microbes,

magnets, and molecules all fall into this class. It is important to recognize that

for people as scientific as Locke, who was a member of the Royal Society, all

of these were part of the same class. It took many centuries to separate science

from religion and superstition.

George Berkeley

Locke is part of a philosophical tradition called empiricism, that is, the

view that the sole or at least the major source of human knowledge is sensory

experience. George Berkeley (1685-1753) was the next great adherent of

empiricism. In his major work, Treatise Concerning the Principles of Human

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Knowledge (1710), he divides ideas into three types: Ideas that come from

sense correspond to Locke’s simple ideas of sensation. Ideas that come from

“attending to the passions and operations of the mind” correspond to Locke’s

ideas of reflection. Ideas that come from compounding, dividing, or otherwise

representing ideas, correspond to Locke’s compound ideas. An apple, for

example, is a compound of the simple ideas of color, taste, smell, and figure

associated with it.

In addition to ideas, what exists are spirits or souls or minds. By “spirit,”

Berkeley means “one simple, undivided, active being.” Spirit exercises itself

in two ways: in understanding and in willing. Understanding is spirit

perceiving ideas, and will is spirit producing ideas. It is evident, says

Berkeley, that no idea, including those of sensation, can exist outside of a

mind. This is evident, not merely in virtue of the meaning of “idea” but what

it means to exist. For a table to exist is for someone to see or feel it. To be an

odour is to be smelled. To be a sound is to be heard. In short, for nonthinking

beings, esse is percipi (to be is to be perceived).

The question whether a tree falling in a virgin forest makes a sound is

inspired by Berkeley’s philosophy, though he never asked it in those terms.

He did, however, consider the thrust of the objection and gave various

answers to it. He sometimes says that a table in a room unperceived is a table

that would be perceived if someone were there. This conditional response,

however, is not sufficient. Granted that the table would exist if it were

perceived, does it exist when it is not perceived? Berkeley’s other answer is

that, when no human is perceiving a table or other such object, God is; and it

is his thinking that keeps the otherwise unperceived object in existence.

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However strange his doctrine may initially sound, Berkeley claimed that

he was merely describing the commonsense view of reality. To say that

colors, sounds, trees, dogs, and tables are ideas is not to say that they do not

really exist. It is merely to say what they are. To say that animals and pieces

of furniture are ideas is not to say that they are diaphanous, gossamer, and

evanescent. Opacity, density, and permanence are also ideas that partially

constitute these objects.

Berkeley has a syllogistic argument for his main point: physical things,

such as trees, dogs, and houses, are things perceived by sense, and things

perceived by sense are ideas; therefore, physical things are ideas. If one

objects that the first premise is false, Berkeley in reply would challenge the

objector to point out one example of something that is not sensed. The only

way to identify such an example is through some sensation, either by sight,

touch, taste, or hearing. In this way, any proffered counterexample becomes

an example of Berkeley’s point.

If one objects that the second premise of the syllogism is false on the

grounds that people sense things, not ideas, Berkeley would reply that there

are no sensations without ideas and that it makes no sense to speak of some

additional thing which ideas are supposed to represent or resemble. Unlike

Locke, Berkeley does not believe that there is anything “behind” ideas in a

world external to the mind. There could not be. If the alleged external objects,

of which ideas are supposed to be representations, exist, then they are

themselves either ideas or not. If they are ideas, then Berkeley’s point that

everything perceived is an idea is vindicated. If they are not ideas, then they

are unperceived; in particular, they would be invisible colors, intangible

textured things, odourless smells, and silent sounds. If someone objects that he

can imagine trees or books in a closet unperceived, Berkeley would reply that

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this proves nothing except that there are imagined trees and books. People

who think that there are unperceived objects are deceived because they do not

take into account their own thinking of the allegedly unperceived object.

A consequence of this argument is that Locke’s distinction between

primary and secondary qualities is spurious. Extension, figure, motion, rest,

and solidity are as much ideas as green, loud, and bitter are; there is nothing

special about the former kinds of ideas. Furthermore, matter, as philosophers

conceive it, does not exist and indeed is contradictory. For matter is

supposedly unsensed extension, figure, and motion, but since extension,

figure, and motion are ideas, they must be sensed.

Berkeley’s doctrine that things unperceived by human beings continue to

exist in the thought of God was also not novel. It was part of the traditional

belief of Christian philosophers from Augustine onward through Aquinas and

at least to Descartes that God not only creates all things but keeps them in

existence by thinking of them. In this view if he were ever to stop thinking of

a creature, it would immediately be annihilated.

On another matter, the doctrine of abstraction, Berkeley made a clean

break with the past. Berkeley rejected it completely, because he thought it led

to belief in unperceived, nonspiritual substances. Abstractionism, according to

Berkeley, illicitly warrants the separation of existence from being perceived.

For him every idea is particular and of a particular object. There cannot be an

idea of motion in general but only of a certain body moving slowly or quickly.

To reject abstract ideas is not to reject general ideas. An idea is general in

virtue of “being made to represent or stand for all the other particular ideas of

the same sort.” That is, each general idea is a particular idea that stands for

many things.

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David Hume

Although Berkeley rejected the Lockean notions of primary and

secondary qualities and matter, he retained Locke’s beliefs in the existence of

mind, substance, and cause as a power or secret force. David Hume (1711-76),

in addition to rejecting all the Lockean notions that Berkeley did, also rejected

what Berkeley had retained. His justification for this step was empiricist and

scientific, for he thought that all science is empiricist and that there is no

empirical justification for belief in mind or spirit.

Hume aspired to be the Newton of philosophy. As stated in A Treatise of

Human Nature (1730-40), he wanted to formulate universal principles to

explain “all effects from the simplest and fewest causes,” but a boundary

condition on these principles is that they “cannot go beyond experience.”

Further, the ultimate principles that humans can form will themselves lack

justification. They will explain experience without having an explanation of

their own.

Kinds of Perceptions

Hume has a twofold division of perceptions: impressions and ideas.

Impressions are perceptions that enter with “most force and violence.” Ideas

are “faint images” of impressions. Hume thinks the distinction so obvious that

he demurs from explaining it at any length. Impressions are felt; ideas are

thought, he indicates in his summary explication. He also concedes that,

although one can always discern the difference between an impression and an

idea by its force, sleep, fever, and madness sometimes produce ideas that

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approximate to the force of impressions, and certain impressions approach the

weakness of ideas. But such occasions are rare.

The distinction has a problem that Hume did not notice. The impression

(experience) of anger has an unmistakable quality and intensity, but it is not

the case that the idea of anger always makes a person feel angry. Thinking of

anger no more guarantees being angry than thinking of the idea of happiness

guarantees being happy, even if thinking happy thoughts tends to make people

happy. So there is a difference between the experience of anger and the idea

of anger that Hume’s philosophy does not capture.

In addition to impressions and ideas, perceptions can be divided into the

categories of simple and complex. Whereas simple perceptions are not subject

to further separation or distinction, complex perceptions are. For example,

apples, although unitary objects in one view, are in fact complex perceptions;

they are divisible into a certain shape, color, texture, and aroma. It is

noteworthy that for every simple impression there is a simple idea that

corresponds to it and differs from it only in force and vivacity, and vice versa.

So, corresponding to the impression of red is the idea of red. This does not

hold true in general for complex perceptions. Although there is a

correspondence between the impression of an apple and the idea of an apple,

there is not always a correspondence between impressions and ideas. There is

no impression that corresponds to the idea of Pegasus or a unicorn; these

complex ideas do not have a correlate in reality. There are also complex

impressions that do not have a corresponding idea. A traveler who has seen an

extensive part of Rome nonetheless does not have an idea of Rome that

corresponds in every respect to his perceptions.