1: Appearance and Reality

Whatever is real (if indeed there is anything real), it cannot be the same as what it merely appears to be. A table may appear to be of many different colors and shapes, depending on the angle from which it is viewed, but this does not mean that the real, physical table is undergoing any changes.

2: The Existence of Matter

Descartes famously doubted all except, finally, cogito ergo sum. This is a good starting point for philosophy. Having doubted the existence of everything except for something-that-perceives (which need not be an enduring I), how can we allow ourselves to believe in external reality?

Russell says that believing in external objects is the simplest explanation for why we perceive the things we do, and there's no good reason to believe any other explanation, so we might as well accept it.

3: The Nature of Matter

Matter seems to have some properties that seem to correspond with the sense-data caused by that matter, but we can't really know anything about any of this other than, Russell says, of the relations between things. Greater or lesser distance, but not absolute distance, for example.

4: Idealism

Bishop Berkeley (George Berkeley, 1685–1753) suggested that objects exist only in perception, and the persistence of apparently real physical objects is because they are always perceived by God. Therefore, the correspondence of different peoples' perceptions of objects is not due to the external reality of the object, but due to the sharing in God's perception.

5: Knowledge by Acquaintance and Knowledge by Description

Distinguish acquaintance and description:

• we are acquainted with "anything of which we are directly aware, without the intermediary of any process of inference of any knowledge of truths"
  • we are acquainted with the sense-data we perceive–though not the objects themselves or any related truths
  • it is not possible to doubt the sense-data itself (though it is possible to doubt that there is some corresponding object)
  • we can have acquaintance by memory: when we recall something with which we were previously acquainted, we are immediately aware of what we remember
  • we can have acquaintance by introspection: we can have knowledge of our mental states, including the fact that we are presently aware of something, our desires, and our thoughts
    • Russell speculates that animals lack the power of introspection–thus although they are aware of sense-data, they are not aware that they are aware of sense-data. It is controversial whether animals have a theory of mind comparable to humans (“Theory of Mind in Animals,” 2021).
  • we are acquainted with universals, "general ideas, such as whiteness, diversity, brotherhood, and so on"
    • "awareness of universals is called conceiving, and a universal of which we are aware is called a concept"
• by contrast, the knowledge of physical objects which cause the sense-data is knowledge by description
  • by description Russell means a phrase like "a foo" (an ambiguous description) or "the foo" (a definite description)

6: On Induction

Russell addresses the problem of induction.

7: On our Knowledge of General Principles

Russell describes a problem like Carroll's "What the Tortoise Said to Achilles" (Carroll, 1895).

Various logical principles are understood a priori, and cannot be proved by experience. Also, Russell asserts, "knowledge as to ethical value", meaning whether one thing is more desirable than another, is a priori, as is all pure mathematics.

8: How A Priori Knowledge is possible

9: The World of Universals

Call as universals Plato's forms, and particulars the objects that share in those universals. Russell indicates that even if we wish to deny that universals such as 'whiteness' do not exist, as such (but are rather verbal conveniences to speak of similarities between objects of a given class, i.e. white things), we cannot deny that relationships (such as 'similarity') between two objects exist, and these relationships are themselves universals.

The confusion, Russell asserts, is that philosophers have focused on universals that are named by adjectives and nouns, ignoring those, such as relationships, that are typically named by verbs, prepositions, etc. So universals have been viewed as qualities predicated of a single object, and the discussion has been thus limited.

Bibliography