The Problems of Philosophy - Chapter 13

(Originally written September 23, 2005 in Book 2)

The Problems of Philosophy
Bertrand Russell
1912

Chapter 13: Knowledge, error, and probable opinion

Knowledge is what is validly deduced from known premises. This is a circular definition because it makes the assumption that 'known premises' is already known what to mean. This definition of knowledge can be used for derivative knowledge.

Derivative knowledge is what is validly deduced from premises known intuitively. This is not circular bit it still leaves us wondering what 'intuitive knowledge' is.

Psychological inference is a way that which which we pass beliefs from one another without the use of logical inference.

The definition of knowledge is not a precise conception, it merges into probable opinion.

There are two ways that a fact may be known:
1. Through the use of a judgment, in which its parts are judged to be related as they are in fact related (my hand writing in this sentence was particularly poor, it may have read 'are judged to be related as they are intact and related' or 'inferred related', but the gist of this sentence is lost on me since I wrote it over a decade ago).
2. Through acquaintance with the fact (which can be broadly called perception)

Two types of self-evidence
1. One that gives an absolute guarantee of truth
2. One that gives a partial guarantee of truth (in my margins I wrote "if it only is partially true, it is partially false and therefore is not self-evident, we only believe it is")

A self-evident truth that guarantees truth is guaranteed by the fact that it corresponds with acquaintance we have.

Mental facts and all facts concerning sense-data have a privacy which makes them unique to only the individual that knows them.  All knowledge of particulars falls under this.

The second type of self-evidence will have varying degrees.

What we firmly believe, that is true, is knowledge. What we firmly believe that is false, is error.

What we firmly believe that is neither knowledge nor error and what we hesitantly believe is probable opinion.

A body of individual probable opinions that are mutually coherent become more probable than any individual probable opinion in the body.