The reasons for accepting Einstein’s law of gravitation rather than Newton’s are partly empirical, partly logical. We will begin with the former.

Before tackling Einstein’s law, it is as well to convince ourselves, on logical grounds, that Newton’s law of gravitation cannot be quite right.

The pursuit of quantitative precision is as arduous as it is important. Physical measurements need to be made with extraordinary exactitude.

One of the most fascinating of the speculations to which I have been alluding is the suggestion that the universe may be of finite extent.

In the Newtonian system, bodies under the action of no forces move in straight lines with uniform velocity.

One of the most difficult matters in all controversy is to distinguish disputes about words from disputes about facts.

The question “What is matter?” is of the kind that is asked by metaphysicians, and answered in vast books of incredible obscurity.

Is there any knowledge in the world which is so certain that no reasonable man could doubt it?

The Problem of Philosophy, by Bertrand Russells, is part of the HackerNoon Books Series. Enjoy the preface of this long-time classic.

In this chapter we have to ask ourselves whether, in any sense at all, there is such a thing as matter.

Physical science, more or less unconsciously, has drifted into the view that all natural phenomena ought to be reduced to motions.

In this chapter we shall be concerned exclusively with knowledge of things, of which in turn we shall have to distinguish two kinds.

For no very good reason, three of these principles have been singled out by tradition under the name of 'Laws of Thought'.

In the present chapter we have to consider what is the nature of this kind of being, and also what objects there are that have this kind of being.

Immanuel Kant's most distinctive contribution to philosophy is something he called 'critical philosophy'. A venture that inquired how knowledge was possible.

Man's knowledge at a given time, universals, like particulars, may be divided into those known by acquaintance, description and those not known by either.

There is a common impression that everything that we believe ought to be capable of proof, or at least of being shown to be highly probable.

Our knowledge of truths, unlike our knowledge of things, has an opposite, namely error.

Philosophers claim to prove religious dogmas, universe's rationality, illusion of matter, and unreality of evil through metaphysical reasoning.

Having now come to the end of our brief and incomplete review of the problems of philosophy, we should consider, in conclusion, what is the value of philosophy.