The Problems of Philosophy: Brief and Accessible Guide to the Problems of Philosophy - Bertrand Russell's Philosophical Exploration: Navigating the Problems of Philosophy

by Bertrand Russell

The fact is that, in simple mathematical judgements such as ‘two and two are four', and also in many judgements of logic, we can know the general proposition without inferring it from instances, although some instance is usually necessary to make clear to us what the general proposition means. This is why there is real utility in the process of deduction, which goes from the general to the general, or from the general to the particular, as well as in the process of induction, which goes from the particular to the particular, or from the particular to the general. It is an old debate among philosophers whether deduction ever gives new knowledge. We can now see that in certain cases, at least, it does do so.