P. Theories of Knowledge

1. Skepticism
Denies the possibility of a complete or genuine knowledge of an objective world, i.e., of a world apart from the knower or his experience. It may doubt the possibility of knowledge of the self as well and confine knowledge to sense data and their associations, as, e.g., did Hume, who confined knowledge and reality to the "stream of perceptions" as impressions and ideas.
Forms of skepticism:
a. Solipsism: I alone exist, because I cannot know a world beyond myself and my ideas. This view leads to the egocentric predicament.
b. Sensory skepticism: sensations are relative and unreliable because they are modifications of the knower and no more a part of the world than is the pinprick a part of the pin.
c. rational skepticism: the conclusions of reason are contradictory or paradoxical.
d. methodological skepticism: a systematic but tentative doubt is a prelude to genuine knowledge.

2. Subjectivism
Subjectivism argues that because knowledge is confined to ideas in the mind of the knower, it is impossible to get beyond these ideas to an objective or material reality separate from and independent of the knower. Perceptions and things known are one (epistemological monism) and can only be known as ideas in the mind of the knower (epistemological idealism). Hence the world is in a knower or belongs to a knower. even if ideas represented an independent reality, as realism contends, one could not possibly know it. "Even if physical objects do not exist when no one is observing them, we can have no reason to suppose that they do for no one can observe them existing unobserved."
To be is to perceive or to be perceived (Berkeley)

The world consists of perceivers and perceptions, minds and ideas.
Berkeley's arguments for subjective idealism:
1. perceptions do not exist unperceived
2. physical objects are complexes of perceptions
3. Therefore, physical objects do not exist unperceived.

3. Objectivism
Objectivism believes that objects are independent of mind and present their properties directly to the knower through sense data. Things known and sense data are one (epistemological realism as epistemological monism).
Objective idealism:
The objective world is mental but objective, i.e., independent of the human knower alone, because it belongs to an absolute knower or world mind.

4. Critical or representative realism
Critical or representative realism (epistemological dualism) ascribes a critical role to mind in the formulation of knowledge. Unlike pure objectivism, it distinguishes between sense data and the objects they represent (epistemological dualism). But the objects or things known are independent of mind or the knower in the sense that thought refers to them -- no merely to sense data or to the ideas of the knower. Ideas represent objects.
a. representative realism:
Ideas represent or correspond to the objects of an independent world. Objective or primary qualities of objects elicit subjective or secondary qualities. Together they comprise knowledge (Democritus, Galileo, Kepler, Descartes, Locke, Macintosh)
Descartes' argument for representative realism:
1. God exits; i.e., the clear and distinct idea we have of God implies his existence just as the idea of a triangle implies three-sidedness.
2. God, by definition, is perfect; i.e., he is benevolent.
3. A benevolent God would not leave us without a way to know the world.
4. This way is reason; i.e., intuition and deduction.
5. If ideas are clear and distinct, then they are true.
6. If ideas are true, they are about what exits.
7. An external world having none but primary qualities is amenable to mathematical analysis and can be clearly and distinctly understood.
8. Therefore, the external world has nothing but primary qualities.
b. critical realism:
Material objects are known via sense data. In Santayana, e.g., knowledge of independently real material things is possible through the joint participation of the knower and things known in the senses. Material things are known indirectly by the act of animal faith (Santayana, Lovejoy, Sellars).

5. Personalism
Personalism (or personal idealism) is an epistemological dualism combining elements of objectivism, realism, and idealism. In Brightman, e.g., there is the dualism of "situation-experienced and situation-believed-in."

6. Neo-Thomism
According to Mascall, Maritian, Gilson, Copleston, sense data are the means "through which the intellect grasps in a direct but mediate activity, the intelligible extramental reality, which is the real thing.

7. Intuitionism
Intuitionism stresses the immediacy of knowledge or the self-evident character of certain ideas. Whenever a "whole response" of the knower to the "whole of things" is suggested, intuition is usually implied. As the theory of knowledge of mysticism, intuitionism teaches the inseperateness of knower and thing known. Realism separates object and knower; idealism holds that all objects belong to some knower; mysticism (intuitionism) holds that the objects and the knower belong to each other; they are one.
More characteristic of Eastern than Western theories of knowledge, intuitionism seeks knowledge of the indefinable or nonanalyzable. Yet there may be attempted expression in symbols or poetry. Concerning the communication of knowledge, Lao-tze observed: "one who knows does not talk. One who talks does not know."

8. Pragmatism
Primarily, pragmatism is a theory of meaning and truth. It stresses the genetic and instrumental character of knowledge. Pragmatism approaches knowledge in terms of an organism that:
a. adapts to and interacts with its environment
b. uses ideas as instruments or plans of action
c. retains ideas that work as true and discards those that fail as false.
Pragmatists emphasize the experimental method. It is a method of knowledge that is open to the test of criticism of others.
Knowledge is the successful determination or reorganization of experience through what Dewey called a "transaction." Pragmatism pictures an active organism developing knowledge from a successful encounter with experience. What is claimed as knowledge must be capable of public confirmation.
Forms of Pragmatism:
a. radical empiricism
b. pragmatism
c. experimentalism (or instrumentalism)

9. Phenomenalism
Phenomenalism is the doctrine that it is phenomena and not things that are known. In agreement with skepticism and subjectivism, phenomenalism denies the possibility of knowledge of objective reality Only objective phenomena are known. Hence knowledge is limited to the totality of actual or possible sense data, including the sense data of internal experiences, such as feelings, dreams, hallucinations, and fantasies. Objects are logical constructs of sense data. They are inferred from sense data.
Phenomenalism differs from subectivism on two points:
a. The world is all the possible as well as all the actual complexes of sensations and ideas. Perceivability -- not actual perception -- determines existence. Matter is the permanent possibility of sensation.
b. What is experienced is not just subjective sensations but objective sense data; i.e., phenomena which are neither mental (subjectivism) nor material (some forms of objectivism).
Phenomenalism differs from objectivism in denying that an objective mental, material, or neutral world is known. Phenomena -- sense data -- are the sole source and object of knowledge. Some phenomenalists deny that there is reality behind phenomena. Others believe that there may be but that it is unknowable. Hence, knowledge is limited to objective sense data alone, and physical objects are logical constructs of sense data.
Forms of Phenomenalism:
a. Pure phenomenalism
b. Kantianism
c. Empirical positivism
d. logical positivism