The Problems of Philosophy

The book is recommended as an introduction to philosophy. In some way, it is as it gives a brief overview of the subject, but it is also dense as it attempts to condense a lot of concepts into a single book for layman.

It took a month to finish the book. I don't understand the majority of details and nuances, but I'm content that I've learnt a bit more about the subject.

Chapter 1 - Appearance and Reality

What I see as a table is not exactly the table itself but what my senses perceive and construct.

Chapter 2 - The Existence of Matter

There is not a significantly strong argument that the table actually exists outside of our senses.

Knowledge is built upon our instinctive beliefs. Some beliefs are stronger than others. If one is found to be mistaken, it's to be replaced by another, more correct belief.

Chapter 3 - The Nature of Matter

There's no evidence that matters have intrinsic properties. For example, the color of a table is a result of light waves reaching our eyes. If we modify the air, the color changes. Thus, it can't be argued that the table actually has colors.

Chapter 4 - Idealism

There's a difference between the act of apprehension and the apprehended object. The act (see, hear, touch...) is mental and in our mind, the object isn't.

Chapter 5 - Knowledge by Acquaintance and Knowledge by Description

Knowledge by acquaintance: we're directly aware of.

  • When I perceive the table, I'm acquainted with the sense-data (color, shape, hardness...).
  • We also use introspection to collect data from inner sense (thoughts, desires, feelings...). Not only we're aware of things but we're also aware of being aware of things; this is called self-consciousness.
    • Tangent: when I meditate, who is the I that is observing?
  • We have acquaintance in memory. We remember and can recall what we have acquainted in the past.

Knowledge by description: inferred from knowledge by acquaintance.

  • I know a description of the table, based on the sense-data. The physical table itself isn't known to me.

Chapter 6 - Induction

Frequent repetition of some uniform succession or coexistence leads us to expect the same succession and coexistence on the next occasion.

The sun has risen for 30 years of my life, I expect the sun will go up tomorrow. The oftener the sun rises, the more probable it will rise tomorrow. As more time passes and the sun keep rising, the probability will amount almost to certainty. It'll never reach certainty because there's a chance of failure (the sun will die some day in the future, earth may collide with an asteroid and stop rotating).

Chapter 7 - On Our Knowledge of General Principles

All knowledge is elicited and caused by experience; some knowledge is a priori, experience doesn't suffice to prove it.

Induction goes from particular to particular or from particular to general.

Deduction goes from general to general or from general to particular.

Chapter 8 - How a Priori Knowledge is Possible

I couldn't summarize the chapter as I don't really understand the main point.

Chapter 9 - The World of Universals

For Plato's theory of ideas, what is justice?

We need to consider just acts and find out what they have in common. They must have some common nature which can be found in just acts and in nothing else. The common nature will be justice itself. The idea "justice" is not particular, it's eternally itself, immutable and indestructible (I don't understand the leap from not particular to timeless).

A universal is anything which is shared by many particulars, and has characteristics which distinguish justice from just acts.

A sentence is made up by at least one word which denotes a universal. In "I like this" sentence, "like" is a universal because I may like other things and other people may like things.

All truths involve universals and all knowledge of truths require acquaintance with universals.

Chapter 10 - On Our Knowledge of Universals

Knowledge of Universals come from acquaintance. When I see a brown table, I'm acquainted with the particular table. After seeing multiple brown tables, I can abstract the brownness which they all have in common and from that I become acquainted with brownness universal.

Similarly, I'm also acquainted with relation (left, right, before, after, similar, different...).

Returning back to priori knowledge, they deal exclusively with relations of universals. We may know a general proposition without knowing a single instance of it.

Chapter 11 - On Intuitive Knowledge

Some general principles are self-evidence, incapable of proof.

Truths of perception are self-evidence truths which are derived from sense-data.

In addition to sensation, our intuitive judgements also employ memory. However, memory can be fallacious so it has degrees of self-evidence corresponding to the degrees of its trustworthiness. Events which are vivid and recent have higher level of trustworthiness and self-evidence.

Degrees of self-evidence, ordered from highest:

  • Truths of perception, some principles of logic and truths of immediate memory.
  • The inductive principle.
  • Memories as we go further into the past
  • The truths of logic and maths as they become more complicated.
  • Judgements of intrinsic ethical or aesthetic value.

Chapter 12 - Truth and Falsehood

We may believe what is false as well as what is true. Many people hold different and incompatible opinions on the same subjects, some of those beliefs are erroneous.

Truth must have an opposite, falsehood. If there is no beliefs, there would be no truth or falsehood. The truth and falsehood of a belief depends upon something which lies outside the belief itself.

Beliefs depend on the mind to exist but do not depend on the mind for their "truth".

For every act of judgement, there's a mind which judges and there are several terms which it judges. When A believes B loves C, A is the judge, while B, loving and C are the objects to be judged. The "B loves C" is a complex unity, which is also called "fact corresponding to the belief". A belief is truth when there's a corresponding fact and false when there is not.

Chapter 13 - Knowledge, Error, and Probable Opinion

A true belief isn't knowledge when it's deduced from a false belief. When a logical process is fallacious, a true belief derived from it can not be considered knowledge.

Theoretically there are 2 ways a fact can be known by:

  • judgement, several parts are judged to be related as they are in fact related.
  • acquaintance with the complex fact itself.

The second way is only possible if its parts have relation which makes them combine to form a complex. The first way gives us parts and relation severally, the relation may not relate parts in that way and yet the judgement may occur.

A truth is self-evident when we are acquainted with the corresponding fact. When A believes B loves C, if the belief is true, the corresponding fact is "B's love for C". Only B may have an acquaintance with this fact, so the truth (if it's a truth) is only self-evident to B.

Intuitive knowledge is trustworthy in proportion to the degree of its self-evidence. What we firmly believe, if it's true, is called "knowledge", provided it's either intuitive or inferred from intuitive knowledge. What we firmly believe, if it's false is called "error". What we firmly believe, if it is neither knowledge or error, and also what we believe hesitatingly, because it's derived from something with lower degree of self-evidence, may be called "probable opinion".

Chapter 14 - The Limits of Philosophical Knowledge

Philosophy is a criticism of knowledge. It's determined to consider each piece of knowledge on its own merits, then retain or reject them after consideration is completed.

Chapter 15 - The Value of Philosophy

As soon as definite knowledge concerning any subject become possible, this subject ceases to be called philosophy, and becomes a separate science.

The value of philosophy is to be sought in its uncertainty. The man who has no idea of philosophy goes through life imprisoned in the prejudices derived from common sense, from beliefs of his age or his nation. To them, the world becomes more definite, finite, obvious. As soon as we philosophize, most everyday things lead to problems to which only incomplete answers can be given. Though, unable to tell us what is the true answer, philosophy is able to suggest possibilities. While diminishing our feeling of certainty as to what things are, it increases our knowledge as to what they may be; it shows familiar things in an unfamiliar aspect.

Philosophical contemplation enlarges both the Self and not-Self.