Haroutune Dadourian on Herbert Dingle

Haroutune Dadourian published The Principle of the Unobservable in The Scientific Monthly 59 (4) (1944), 293-295. In it he discusses some ideas of Herbert Dingle and we give below a version of that part of his article.

The Principle of the Unobservable

From Galileo to Einstein, the physicist went about his researches as if he believed in the principle: that which is unobservable is not significant. He did not formulate this principle, however, or consciously make use of it. But because he was looking for observables, he generally avoided unobservables.

Einstein was probably the first physicist to recognize the value of the principle and to use it consciously. He stated it, in connection with the concept of the simultaneity, in the following terms:
The concept does not exist for the physicist until he has the possibility of discovering whether or not it is fulfilled in an actual case. ... As long as this requirement is not satisfied, I allow myself to be deceived as a physicist (and of course the same applies if I am not a physicist), when I imagine that I am able to attach a meaning to the statement of simultaneity.
In a very stimulating article, Herbert Dingle points out that this statement of Einstein has been acclaimed as a great discovery by some physicists and philosophers, while it has been condemned as pure nonsense by other physicists and philosophers. Dingle ascribes this divergence of opinion to the fact that the concept of the unobservable has not been analysed and clearly defined. He analyses the concept and from it draws some startling conclusions. He classifies unobservables under three heads: the logically, the physically, and the practically unobservable. The logically unobservable is that which violates laws of reason. The physically unobservable is that which cannot be observed by any possible means of observation. The practically unobservable is that which cannot be observed by any known means of observation, but could be observed if these means were refined and perfected to the theoretical limits of their possibilities.

But, according to Dingle, if we assert that something is physically unobservable, while believing in the existence of the external world, we should be assuming that we know all the possible means of observing it. That would be tantamount to presuming omniscience. Dingle concludes, therefore, that we face the dilemma of giving up either the principle of the unobservable or the belief in the external world.

Dingle would retain the principle and give up the belief. For if the principle were abandoned there would be no check to empty speculation and idle invention. As an illustration of what might happen, he says:
Suppose, for example, I assert that there is a binkum sitting on the table in front of me, and that this tremendous fact, rightly understood, is the final, completely satisfying solution of the problem of evil. If you reject the principle in question, you have no grounds for denying the statement. You may say that you cannot detect my binkum, but I reply that of course you cannot, because he is unobservable. If you want to know how his existence solves the problem of evil, I say that it is its nature to do so, and the definition of him, according to your own contention, is quite independent of any means you adopt to investigate him . . . . Stupid as this example sounds, it contains a precise parallel to the case of simultaneity.
Dingle is thus led to the conclusion that we must give up the belief in the external world and adopt the idealistic view. In the article he does not state what he means by the 'idealistic view.' This he does, however, in his book Through Science to Philosophy. His comments on the following quotation from Eddington's The Nature of the Physical World shows clearly that his idealistic view is indistinguishable from solipsism:
The only subject presented to me for study is the content of my consciousness. You are able to communicate to me part of the content of your consciousness which thereby becomes accessible to my own. For reasons which are generally admitted, though I should not like to have to prove that they are conclusive, I grant your consciousness equal status with my own.
Dingle says: "It is clear that there is an inconsistency because other person's consciousness is said to be partly in his own and yet to have equal status with it." Commenting further on Eddington's idealism he continues:
... to say that solipsism is logically irrefutable is to express the fact too mildly. It is not merely irrefutable; it is absolutely true .... The real problem is having admitted the necessity of solipsism as a starting-point, to proceed from it to give a satisfactory interpretation to experience as we know it.... He is too honest to obscure the fact that solipsism is the logical starting-point, but instead of starting from it he jumps a gap, for reasons which he would not like to have to prove were conclusive, and sets out with obviously incompatible consciousnesses forced to an impossible equivalence.
It seems to me that both Eddington and Dingle are stating self-contradictory propositions. For if I were a solipsist, you would have existence to me only by virtue of being a part of my consciousness; consequently whatever you communicate to me would be a part of a consciousness which is a part of my consciousness; which makes no sense. Besides, what meaning could I then attach to the word communication?

Whether I grant your consciousness an equal or inferior status with mine, you could not successfully challenge any binkum which I may invent, because the challenge would be from a part of my consciousness to another part. It appears therefore that by adopting solipsism in order to exclude binkums, Dingle opens the door wide to them to come in.

Furthermore, if I proceed from solipsism as a starting-point what would happen? In the process everything external to "myself " would vanish first into nonexistence; then my own body would disappear with the rest of the non-existent, unreal world; even my past would follow suit. Thus the "real" world would reduce to the momentary "I," the epitome of my consciousness of the present moment. As time passes, the "I" which was real at one moment would merge continuously into the limbo of the vanishing external world, and a new real "I" would appear in its place. Thus, in Minkowski's space-time diagram, there would be only one point-event, the one that represents he ever- present "I.".

Therefore if I proceed from solipsism as a starting-point, I finally arrive at the purest stage of solipsism where there are neither observables nor unobservables; consequently the principle which Dingle is rightly anxious to preserve becomes a collection of meaning- less words. At that stage science and philosophy, in fact all human activities, lose significance and meaning.

So far the argument stands as follows: Because of its usefulness, the principle unobservable should be retained if possible. But if we accept the principle, while believing in the external world, we place ourselves in the untenable position of presuming omniscience. On the other hand, if we renounce the belief in the external world and adopt solipsism, we not only reduce the principle to a meaningless jargon but also get involved in endless logical absurdities.

Dingle has made a real contribution by analysing the concept of the unobservable, by formulating the principle of the unobservable, and by stressing its importance. But he has drawn unsound conclusions from his analysis as a result of adopting unscientific definitions for the three classes of unobservables. Dingle's dilemma is of his own making and springs from his definitions may be shown from a consideration of the following quotation:
Let us suppose that we have discovered all the means of observation that exist in the universe, and know all their properties completely. We might then be able to imagine other means of observation which do not exist. Anything which would be observable by such imaginary means, but not by existing means, would be physically unobservable. Anything which would be unobservable by any means, existing or imaginable, would be logically unobservable. Anything which would be observable by the existing means if we were also omnipotent, but which is actually unobservable because we cannot make full use of the means of observation which exist, would be practically unobservable. ... If we assume that we are omniscient we can distinguish three classes - the practically, the physically and the logically unobservable. If we do not assume that we are omniscient we can distinguish only two classes - the actually and the logically unobservable, let us call them.
By adopting definitions in terms of omniscience and omnipotence Dingle falls victim to the kind of fallacy involved in dividing two members by infinity and then equating the results to prove that two unequal numbers are equal. These definitions are not scientific definitions in that they do not specify practical criteria by means of which the concepts defined could be distinguished from other concepts.

Last Updated July 2020