A foundational introduction to philosophy. It's a relatively short book but requires a lot attention and reflection afterward. Russell's writing has the unfortunate quality of being difficult to read, but his arguments and thought process are still quite enlightening.

The first half of the book is more compelling than the second, dealing with theories of knowledge and analysis of reality. I would suggest skipping the other half.

My Notes

Appearance & Reality

The problem of appearance and reality lies in the distinction between the two.

One of the most difficult questions one can ask is if there is any knowledge in the world which is so certain that no man could doubt it. Easy at first sight, hard after pondering.

Russel takes the example of a table.

• To the eye, the table appears oblong, brown and shiny.
  • Even if I believe the table is really of the same color all over, the parts that reflect the light look much brighter than the other parts, and some parts look white because of reflected light.
  • If I change position, the parts that reflect light will be different, so the apparent distribution of color will change.
  • Several people looking at the same table at the same time from different positions will see different colors.
  • Therefore there is no one color that appears to be the unique color of the table. It depends on the spectator (position, blindness, glasses…).
  • We tend to speak of color as the common sort of color we see, but there is no reason that other colors aren’t as real as the one we see.
  • The naked eye can see the grain in the table.
  • With a microscope, we can see roughness and hills and all sorts of differences.
  • With a stronger microscope, we can see even more of these differences, differently.
  • What is the real table, then?
• To the touch, the table appears smooth and cool and hard.
  • There is a sensation of hardness when we touch the table, but the sensation depend upon which part of the body we press with.

The real table, if there is one, is not the same as what we immediately experience by sight or by touch.

To understand this problem, Russell uses the concept of ‘sense-data’ and ‘sensations’.

• Sense-data are the things that are immediately known in sensation (colors, shape, sounds, hardness, and so on).
• Sensations are the experiences of being immediately aware of these things.

Whenever we see a color, we have the sensation of the color, but the color itself is a sense-datum, not a sensation. The awareness of the color is the sensation.

Thus, by taking any object that is supposed to be known by the senses, what the senses immediately tell us is not the truth about the object as it is apart from us, but only the truth about certain sense-data that we can see and depend upon the relations between us and the object.

What we directly see and feel is merely ‘appearance’, which we believe is some sort of ‘reality’ behind.

Knowledge By Acquaintance & Knowledge By Description

All our knowledge, both knowledge of things and knowledge of truths, rests upon acquaintance as its foundation. It is therefore important to consider what kinds of things there are with which we have acquaintance.

Knowledge by acquaintance is direct and immediate. It is the knowledge we have when we are directly aware of something without the need for any inference, description, or intermediary concept.

There are two extensions of knowledge by acquaintances beyond sense-data to be considered:

• Memory: we remember things we have heard or seen in the past. When you see a brown table, you have direct knowledge of the color brown through your perception. This experience is direct and not mediated by any description.
• Introspection: the fact that we are aware of being aware of things. You have knowledge of your own thoughts and feelings. When you feel pain, you are directly acquainted with that experience.

Knowledge by description allows us to extend our knowledge beyond our immediate experiences. It enables us to think and talk about objects, people, and events that we are not directly acquainted with.

By a 'description' means any phrase of the form 'a so-and-so' or 'the so-and-so'.

• ambiguous description: 'a so-and-so' ('a man' )
• definite description: 'the so-and-so' ('the man with the iron mask')

For example, you know about Julius Caesar, but you don't have direct acquaintance with him. Instead, your knowledge comes from descriptions provided in books or lectures.

On General Principles

1. The law of identity: 'Whatever is, is.'
2. The law of contradiction: 'Nothing can both be and not be.'
3. The law of excluded middle: 'Everything must either be or not be.'

One of the great historic controversies in philosophy is the controversy between the 'empiricists' and the 'rationalists'.

• The empiricists (Locke, Berkeley, and Hume) argued that all our knowledge is derived from experience
• The rationalists (Descartes and Leibniz) considered that there are certain 'innate ideas' and 'innate principles', which we know independently of experience.

Rationalists believe in a priori knowledge: independent of experience and can be known through reason alone, without needing empirical validation. Knowledge is called empirical when it rests wholly or partly upon experience.

we shall nevertheless hold that some knowledge is a priori, in the sense that the experience which makes us think of it does not suffice to prove it, but merely so directs our attention that we see its truth without requiring any proof from experience.

A Priori Knowledge

A priroi knowledge is independent of experience. It is knowledge derived from reason alone.

Kant is highly regarded as the inventor of "critical" philosophy. Before him, any form of knowledge was considered analytic, and not synthetic.

• Analytic proposition: the predicate is obtained by merely analysing the subject, and are generally trivial (e.g. 'A bald man is a man')
• Synthetic proposition: no analysis of the subject will reveal the predicate (e.g. 7 + 5 = 12: the idea of 12 is not contained in 5 nor 7)

What Kant maintained was that in all our experience there are two elements to be distinguished:

• the one due to the object (i.e. to what we have called the 'physical object')
• the other due to our own nature.

In discussing matter and sense-data, we saw that the physical object is different from the associated sense-data, and that the sense-data are to be regarded as resulting from an interaction between the physical object and ourselves.

Kant considers that the crude material given in sensation—the colour, hardness, etc.—is due to the object, and that what we supply is the arrangement in space and time, and all the relations between sense-data which result from comparison or from considering one as the cause of the other or in any other way.

His chief reason in favour of this view is that we seem to have a priori knowledge as to space and time and causality and comparison, but not as to the actual crude material of sensation.

We can be sure that anything we shall ever experience must show the characteristics affirmed of it in our a priori knowledge, because these characteristics are due to our own nature, and therefore nothing can ever come into our experience without acquiring these characteristics.

• What can't be known is the physical object, the 'thing in itself', the 'noumenon'.
• What can be known is the object as we have it in experience, the 'phenomenon'.

In spite of the existence of a priori knowledge, we cannot know anything about the thing in itself.

On Universals

There is a difference between justice and a just act. The former refers a concept (a universal); the latter is only a specific representation of the concept (a particular).

Universals are ideas (not to be confounded with our common definition of what comes to mind). They are intangible, referring to what Plato meant when seeking for the highest form of knowledge.

The essence of the sort of entity that Plato meant is that it is opposed to the particular things that are given in sensation.

A universal will be anything which may be shared by many particulars, and has those characteristics which, as we saw, distinguish justice and whiteness from just acts and white things.

By contrast, what is given in sensation are particulars.

Our thoughts, feelings, and minds exist in the sense that we can point to them at a specific moment in time. That is however not true for universals. Universals do not exist, they are timeless and unchangeable.

Particulars exist; universals subsist.

Intuitive Knowledge

If intuitive knowledge had to be classified, it would be as follows:

• knowledge of things
  • knowledge by acquaintance (immediate)
  • knowledge by description (derivative)
• knowledge of truths
  • intuitive knowledge (immediate, self-evident)
  • inferential knowledge (derivative)

Along with general principles, intuitive knowledge is knowledge that is immediately derived from sensation.

• Judgements of perception: judgements that express some self-evident truths, but the sense-data are neither true nor false (e.g. the existence of a patch I see)
• Judgements of memory: judgements drawn from a past experience, though not always accurate

Memory of an object often comes with an image of the object, but the image cannot be what constitutes memory. The image is seen in the present, but what is remembered is in the past.

Thus the essence of memory is not constituted by the image, but by having immediately before the mind an object which is recognized as past.

All our knowledge of the past relies on memory.