In pursuing this analysis, the Viennese logicians have thrown light upon the fact that assertions which have a meaning for science are not those which concern the nature or the essence of that which is, but rather regard the connections between the designations or symbols, which our senses, and especially our instruments of observation and measurement, enable us to elaborate concerning that which appears to us in our Erlebnisse, as the Germans say, that is, in our lived experiences. It is not with the being of things that science is occupied; it is with the mathematical links, which can be established between these designations taken from things, and which alone make possible,—I say in the proper order and in the proper plane of science,—a communication or a well established language, an intersubjectivation, submitted to fixed rules of signification.
If I say this table, these words do not mean for the scientist a hidden substance, presenting itself to me under a certain image and with certain qualities, of which substance, moreover, he can know nothing as a physicist. They mean a certain set of perceptions, linked by expressible regularities—the permanent possibility of sensation of which John Stuart Mill spoke—linked to a certain number of mathematical and logistic designations, which render it intersubjectivable.
If I say matter, this word does not mean for the physicist a substance or a substantial principle, about the mysterious nature of which he might question himself and, if wise, answer with Du Bois-Reymond: ignorabimus. For the scientist, the word ‘matter’ only means a certain set of mathematical symbols, established by microphysics and submitted, moreover, to continual revision, wherein certain highly designable observations and measurements are expressed according to the rules of differential calculus or of tensorial calculus and according to the syntax of certain general theoretical constructions, which are also of a provisional character, such as the quantum theory or the syntheses of wave-mechanics.
All this is excellent, but we must have the courage to go to the end. An assertion such as I am or I exist, proclaimed in the manner of Descartes, for example, has no meaning for the scientist, because to have a scientific meaning an assertion must express a stable relation between designations which can finally be reduced to such or such class of sensory experiences; and existence, in the cartesian formula, is not such a designation. An affirmation such as I speak before an audience of human persons, uttered in the manner of common sense, is also deprived of meaning for the scientist; the person is not a sensori-mathematical symbol which can be handled by science. These affirmations will have a meaning for the scientist only when the words ‘existence’ and ‘person’, after an appropriate reformulation, will have lost all meaning for you and for me.
Generally speaking, all reference to being, or essence in itself, is eliminated as lacking meaning for the scientist; and naturally the rational necessities disappear at the same time. What philosophers call the first principles of reason express at best certain regularities likely to be verified in certain cases, and likely not to be verified in others, according to the logical treatment to which we submit our Erlebnisse. The discussions concerning scientific determinism and Heisenberg’s principle of indetermination, have cast light on this point, in so far as the principle of causality is concerned, or more exactly speaking, so far as concerns the recasting of the idea of causality in the domain of experimental science. And I do not see at all why the principle of noncontradiction, duly deprived of all ontological meaning, should not be exposed some day to the same fate, if upon that day the introduction of the simultaneous value of yes and no in a symbolic expression, should enable us to express mathematically a set of observations and measures with more elegance and ease, or to combine in a general synthesis theories drawn from different sections of science, which could not be otherwise conciliated.
All this means that the intellect is a sort of indispensable witness and regulator of the senses in scientific work, remaining all the while—if I may express myself thus—external to this work. The senses and the measuring instruments alone see in science, and the intellect is there only in order to transform, according to the rules of mathematical and logical syntax, the signs expressing what has thus been seen. The intellect is set up in the central office of the factory, where it checks, and submits to more and more extensive calculations, all the indications which are conveyed to it. It remains outside the quarters where the work is being directly accomplished, and is forbidden to enter.
III
THE THOMIST IDEA OF SCIENCE
The theory of experimental science offered by the Viennese suffers, in my opinion, from certain peculiar philosophical errors which especially concern the notion of logical work and the notion of sign. Logical work, by which the mind passes from one assertion to another by virtue of reasoning and of the connection of ideas, is not, as the Viennese believe, a simple tautological process, wherein we only transform different symbolic expressions of one same thought; it is not a simple reiteration of the same thought, for, in thinking, the mind passes from one truth to another truth.
The notion of sign does not concern our states of consciousness, our Erlebnisse, but objects independent of our subjective states, though constituted in their intelligibility proper by the activity of our intellect.
And, above all, the theory of science offered by the Viennese, suffers from a positivist purism, to which I will return later.
But, so far as a certain characteristic structure of science is concerned, this theory insists upon a fundamental truth which, in fact, the Viennese logicians have not discovered (rather they have received it from the scientists), and which is due to the self-awareness which modern science, and especially physics, has achieved. The truth is, that science—science in the modern sense of the word—is not a philosophy, and consequently claims, if I dare use this barbarism, to deontologize completely its notional lexicon.
This endeavour is more difficult than it may seem. There is something heroic about it. It implies a merciless struggle against language, because language is inevitably loaded with intelligence and with ontology. To consider, for instance, the prose of Joyce or the works of some of our contemporary poets, it is curious to observe how this desperate struggle against language currently characterizes two of the most typical and noblest impulses of spiritual endeavour, in very different fields, the scientific and the poetic. It might be that, truly speaking, the mystics alone are able to succeed in such a struggle: because the mystics have no need of language, at least in a certain zone and at certain moments of experience and actuation.
Let us end this digression. What I should like to note relative to the precise point which I have just indicated, is that the consideration of the sciences of phenomena, as they have developed in modern times,—novel, indeed, by relation to the cultural state of antiquity and the medieval world,—this consideration carried out in the light of the epistemological principles of St. Thomas Aquinas, would lead us to general views strikingly similar to those of the school of Vienna.
Let me sum up as briefly as possible the results which I reached myself, before having been informed of the works of the Viennese group.
What is essential, in my opinion, is both to repudiate the positivist conception of knowledge, which is a philosophical error, and also to take account of the understanding of themselves which the sciences of nature have achieved, a self-consciousness which is itself a spiritual reality, an extremely valuable fruit of experience, and which we cannot ignore without exposing ourselves to a serious mistake.
What is important, it seems to me, is to distinguish (and this the Viennese school has omitted to do) two ways of analysing the world of sensible reality and of constructing the concepts relevant thereto. I have given these two kinds of analysis of