George Berkeley | 6. Philosophy of Nature


George Berkeley
 (1685 –1753)

Philosophy of Nature | Part 6

1. Philosophy of Nature

Berkeley carried on a persistent battle against the tendency to suppose that mere abstractions are real things.

In the New Theory of Vision he denied the possibility of “extension in abstract,” saying:

“A line or surface which is neither black, nor white, nor blue, nor yellow, etc., nor long, nor short, nor rough, nor smooth, nor square, nor round, etc., is perfectly incomprehensible” (§ 123).

In the introduction to the Principles, his most explicit discussion of the matter, he quoted Locke’s account of the abstract idea of a triangle

“which is neither oblique nor rectangle, neither equilateral, equicrural, nor scalenon, but all and none of these at once,”

and pointed out that any actual triangle must be one of these types and cannot possibly be “all and none” of them.

What makes any idea general, he held, is not any abstract feature that may be alleged to belong to it, but rather it’s being used to represent all other ideas that are like it in the relevant respects.

Thus if something that is true of a triangle of one of these types is not true of it because it is of that one type, then it is true of all triangles whatever.

Nothing exists but what is particular, and particular ideas become general by being used as representatives of others like them.

Generality, we might say, is a symbolic device, not a metaphysical status.

Thus Berkeley’s attack on abstractions is based on two principles:

1) that nothing exists but what is particular, and
2) that nothing can exist on its own except what can be sensed or imagined on its own.

If we accept the first principle, then abstract objects and Platonic forms are rejected, and if we accept the second, then possibility is limited to the sensible or imaginable.

2. Space, Time, and Motion.

We have already seen how Berkeley applied the above 2 principles to the abstract conception of unperceived existence, and to the abstract conception of bodies with only the primary qualities.

It must now be shown how he applied them to some of the other elements in the scientific worldview he was so intent on discrediting. Chief among these were the current conceptions of absolute space, absolute time, and absolute motion:

According to Berkeley, all these are abstractions, not realities.
It is impossible, he held, to form an idea of pure space apart from the bodies in it.

We find that we are hindered from moving our bodies in some directions and can move them freely in others:

Where there are hindrances to our movement there are other bodies to obstruct us, and where we can move unrestrictedly we say there is space.

It follows that our idea of space is inseparable from our ideas of movement and of body (Principles, §116).

So too our conception of time is inseparable from the succession of ideas in our minds and from the “particular actions and ideas that diversify the day”; hence Newton’s conception of absolute time flowing uniformly must be rejected (Principles, §§97, 98).

Newton had also upheld absolute motion, but this too, according to Berkeley, is a hypostatized abstraction.

If there were only one body in existence there could be no idea of motion, for motion is the change of position of two bodies relative to one another.

Thus sensible qualities, without which there could be no bodies, are essential to the very conception of movement.

Furthermore, since sensible qualities are passive existences, and hence bodies are too, movement cannot have its source in body; and as we know what it is to move our own bodies, we know that the source of motion must be found in mind.

Created spirits are responsible for only a small part of the movement in the world, and therefore God, the infinite spirit, must be its prime source.

“And so natural philosophy either presupposes the knowledge of God
or borrows it from some superior science” (De Motu, §34).

3. Causation and Explanation.

The thesis that God is the ultimate source of motion is a special case of the principle that the only real causes are spirits. This principle has the general consequence, of course, that inanimate bodies cannot act causally upon one another.

Berkeley concluded from this that what are called natural causes are really signs of what follows them:

Fire does not cause heat, but is so regularly followed by it that it is a reliable sign of it as long as “the Author of Nature always operates uniformly” (Principles, §107).

Thus Berkeley held that natural laws describe but do not explain, for real explanations must be by reference to the aims and purposes of spirits, that is, in terms of final causes.

For this reason, he maintained that mechanical explanations of movements in terms of attraction were misleading, unless it was recognized that they merely recorded the rates at which bodies in fact approach one another (Principles, §103).

Similar arguments apply to gravity or to force when these are regarded as explanations of the movements of bodies (De Motu, §6).

This is not to deny the importance of Newton’s laws, for Newton did not regard gravity “as a true physical quality, but only as a mathematical hypothesis” (De Motu, §17).

In general, explanations in terms of forces or attractions are mathematical hypotheses having no stable being in the nature of things but depending upon the definitions given to them (De Motu, §67).

Their acceptability depends upon the extent to which they enable calculations to be made, resulting in conclusions that are borne out by what in fact occurs.

According to Berkeley, forces and attractions are not found in nature but are useful constructions in the formulation of theories from which deductions can be made about what is found in nature, that is, sensible qualities or ideas (De Motu, §§34–41).

4. Philosophy of Mathematics

When George Berkeley wrote the New Theory of Vision, he thought that geometry was primarily concerned with tangible extension, since visual extension does not have 3 dimensions, and visible shapes must be formed by hands that grasp and instruments that move.

He later modified this view, an important feature of which has already been referred to in the account of Berkeley’s discussion of Locke’s account of the abstract idea of a triangle:

A particular triangle, imagined or drawn, is regarded as representative of all other triangles, so that what is proved of it is proved of all others like it in the relevant respects.

This, he pointed out later in the Principles (§126), applies particularly to size:

If the length of the line is irrelevant to the proof, what is true of a line 1 inch long is true of a line 1 mile long. The line we use in our proof is a representative sign of all other lines.

But it must have a finite number of parts, for if it is a visible line it must be divisible into visible parts, and these must be finite in length.

A line 1 inch long cannot be divided into 10, 000 parts
because no such part could possibly be seen.

But since a line 1 mile long can be divided into 10, 000 parts,
we imagine that the short line could be divided likewise.

Thus it was Berkeley’s view that infinitesimals should be “pared off” from mathematics (Principles, §131).

In the Analyst (1734), he brought these and other considerations to bear in refuting Newton’s theory of fluxions. In this book Berkeley seemed to suggest that the object of geometry is “to measure finite assignable extension” (§50, Q.2).

Berkeley’s account of arithmetic was even more revolutionary than his account of geometry:

In geometry, he held, one particular shape is regarded as representative of all those like it,

but in arithmetic we are concerned with purely arbitrary signs invented by men to help them in their operations of counting:

Number, he said, is “entirely the creature of the mind” (Principles, §12).

He argued, furthermore, that there are no units and no numbers in nature apart from the devices that men have invented to count and measure:

The same length, for example, may be regarded as 1 yard, if it is measured in that unit, or 3 feet or 36 inches, if it is measured in those units.

Arithmetic, he went on, is a language in which the names for the numbers from zero to nine play a part analogous to that of nouns in ordinary speech (Principles, §121).

Berkeley did not develop this part of his theory.

However, later in the 18th century, in various works, Etienne Bonnot de Condillac argued in detail for the thesis that mathematics is a language, and this view is, of course, widely held today.