An enquiry concerning the principles of natural knowledge

by Alfred North Whitehead

Now here a difficulty arises; for we all know that, according to Dalton's atomic theory of chemistry, any apparently continuous substance is a discrete collection of molecules, and that furthermore, according to the more recent theories, a molecule is a discrete collection of electric charges. Accordingly, as we are told, if we could take the minutest drop of water and magnify it, the phenomena would be analogous to those of a swarm of flies in a room.

It would appear therefore that we are mistaken in classifying a drop of water as being a material object.

60.2 The position that we seem to have arrived at is that on the one hand a drop of water is a material object, because it appears to be one and it is whatever it appears to be, and that on the other hand it is really something quite different.

Such paradoxes mean that vital distinctions have been overlooked. We must distinguish between the drop of water as it appears, the event which is its situation, and the character of the event which causes the event to present that appearance. Namely, there is the appearance of the drop of water. This is character No. 1 of the event, the apparent character, and is a material object. Again there is the character of the event which is the cause of character No. 1. This is character No. 2 of the event and is its causal character. According to the doctrine of science, character No. 2 is not a material object.

60.3 But why trouble about causal characters? What has pushed science into their consideration? The impelling reason is the complex bewildering relationships of the apparent characters. Apparent characters essentially involve reference to percipient events, and may be very trivial qualities of the events which they characterise. For example, all delusive perceptual objects are apparent characters of events.

In the case of a delusive perceptual object character No. 2 of its situation has no existence, except so far as the event is necessarily still a 'passive condition' according to the nomenclature of [Chapter VII] of Part II. The active conditioning events for a delusive perceptual object must be sought elsewhere than in its situation. Let us confine ourselves to the consideration of non-delusive perceptual objects, that is, to physical objects.

60.4 But the line of separation between delusive and non-delusive perceptual objects is not quite so clear as we might wish. The definition of delusiveness and non-delusiveness is sufficiently obvious, namely, a perceptual object is non-delusive when it is the apparent character of an event which is itself an active condition for the appearance of that character as perceptible from all percipient events. In the nomenclature of [Chapter VII] of Part II the situation of a physical object is its 'generating event.'

Now if this definition is to be taken to the foot of the letter, all perceptual objects are delusive; for all perception is belated. The sun which we see is the apparent character of an event simultaneous with our percipient event, and this event is about eight minutes subsequent to the generating event corresponding to that appearance of the sun. In the case of other astronomical phenomena the discrepancy is more glaring. In the case of terrestrial perceptual objects the discrepancy is less glaring in many cases, though for sounds it is very insistent and is the reason of their very indeterminate situations. But, speaking generally and admitting exceptions, for the greater part of ordinary domestic perceptions the belatedness of the apparently characterised event behind the causally characterised event is a small fraction of the percipient's specious present.

Accordingly our knowledge of causal characters is a theory built up by ignoring this element of delusiveness in all perceptual objects, and then by introducing it as an additional correction in the exceptional cases.

[61. Transition from Appearance to Cause]. 61.1 But how can we pass from appearance to cause, seeing that our knowledge of nature is confined to awareness of appearance? For example, all measurement is a measurement of appearance.