The Problems of Philosophy - Chapter 6

(Originally written September 20, 2005 in Book 2)

The Problems of Philosophy
Bertrand Russell
1912

Chapter 6 - On induction

Without using induction we have knowledge of the existence of:
1. Ourselves (probably)
2. What we are acquainted with through sense-data
3. Memory: which is the act of remembering past sense-data

To expand our knowledge of existence we must make inferences of our already known (acquired) knowledge.

"Things which we see become associated by habit, with certain... sensations" (Russell, 62).

Uniformity can be misleading, but they nevertheless exist.

Since uniformity is sometimes misleading we must distinguish the fact that past uniformities cause expectations as to the future, from whether or not there is reasonable ground for giving these expectations merit when questions arise of their validity.

The uniformity of nature is the belief that everything that has happened or will happen is an instance of some general law to which there are no exceptions.

"We have reason to know that the future will resemble the past, because what was the future has constantly become the past, and has always been found to resemble the past, so that we really have experience of the future, namely of times which were formerly future, which we may call past futures" (Russell, 64-65).

The fact that two things have been found together often and never apart does not prove demonstratively that they will always be found together. The most it does is lend weight to the belief that it does. It can never reach absolute certainty.

Because of this Russell states: "Thus probability is all we ought to seek" (Russell, 66).

The tool we use to test probability is the principle of induction.

There are two parts to the principle of induction (regarding individual cases).

1. When something of type A is found with something of type B and has never been found alone, the more times A & B are found the higher probability when either A or B is newly discovered the other will be associated with the new discover as well.

2. When #1 is done enough times and never disproved, the probability is almost considered a certainty.

There are two parts to the principle of induction (regarding general laws).

1. The greater number of cases in which A & B are together the greater the probability the general law is true.

2. If a sufficient number of cases is done and found A & B together and never separate, then this general law is almost considered a certainty.

The inductive principle is unable to be proved or disproved by an appeal to experience.

The inductive principle only uses data from an observed class. Any unobserved class experienced later does not alter the probability of the first observed data but can be incorporated to strengthen, weaken or somhow alter the conclusion.

The inductive principle must be accepted on the grounds of its intrinsic evidence or we must give up all our rights to making expectations of the future.