Science and Philosophy at the Turn of the Twentieth-Century: The Logical Positivists and Wittgenstein.


From 1900-1930, the greatest revolutions in physics since the 17th century had a manifold effect on philosophy: some thinkers came to take philosophy now to be the handmaiden of science. A few tried to form their own scientific metaphysics; and many decided that the new science has become too abstract for philosophy to combine with human experience, and they turn against any attempt to incorporate science into philosophy. The most famous and most influential response is the first, which we call positivism. The logical positivists all embraced the first book of a young genius named Ludwig Wittgenstein. After briefly reviewing some of the new science, we will examine positivism and Wittgenstein’s early classic, his Tractatus Logico-Philosophicus.

Special relativity, general relativity, and quantum mechanics, not only changed the scientific view of the world, but essentially make a metaphysical picture of the world difficult to achieve. The special theory of relativity shows that there is no “ether” for light to propagate through – as it was believed necessary before that, that for any kind of electromagnetic radiation to propagate, it had to have a medium; but that seemed not to be true – furthermore, relativity showed that space and time are interdependent, they’re part of one phenomenon called space-time, and space-time measurements are relative to the movement of reference frames. There is no simultaneity at a distance anymore: measurements of lengths of space and time are objective; they’re not dependent on our subjective experience, but they’re relative to the relations and relative velocities of what we measure and what we measure with.

General relativity expands these notions of special relativity and shows that space itself is altered by the bodies in it. Einstein’s field equations in general relativity have vacuum solutions, meaning that there is space-time for Einstein’s theory of general relativity even where there is no matter or substance at all. The invariance of space-time measurements appear only in highly abstract mathematical formulae. But then there is quantum mechanics: Quantum mechanics shows that the small components of matter do not behave like scaled-down versions of macroscopic material objects; they exhibit wave and particle features depending on our interaction with them. They do not have trajectories at all, and as individuals they are indeterministic. So we go from a very strange picture of the world to one that we can’t even picture at all at the microphysical level.

The banishing of the ether and the substitution of relativistic formula for Newton’s laws seem to imply something else as well: that science does not try to know the ultimate underlying entities that cause observable phenomena but merely create mathematical models for predicting observable phenomena. Let me explain: the way Einstein was interpreted by scientists was one thing, but the way he was interpreted by philosophers was a little different; that is, philosophers of science were particularly concerned with the way he came to his conclusions, and it certainly appeared that what Einstein had done was to look at the observations and to change the picture of physical reality to match the observation. In other words, experimental data showed that measured phenomena – for example, the velocity of an object in its time measurements would change as the velocity approaches the speed of light – didn’t make sense to anymore in terms of their picture of the real world, but the observation showed that it was true; the observation showed that there was no ether, so he banished the ether. The general picture that philosophers of science took from Einstein was that we should forget about trying to model or picture things themselves, and focus instead on explaining and predicting observations.

This meant that in a mathematical model employed by physicists, the terms in the model do not need to refer to entities that exist; they only have meaning in the sense of being placeholders that translate observations into predictions. In other words, the presence of a particular variable or a particular concept of an entity in a physical law needn’t imply that the entity really exists as something independent of the law; it merely has to make the equation work out in the end. This was one way of interpreting Einstein’s achievement.

This particular way of interpreting it was, in fact, the view of logical positivism, a movement created by members of what was called the Vienna Circle: Moritz Schlick, Otto Neurath, and Rudolf Carnap, to name a few. They had been influenced by the earlier philosopher of science Ernst Mach, and by what they took to be the methodological implications of Einstein’s theory of relativity. Certainly, the positivists disagreed with each other, but they more or less agreed on the following revolutionary program: for all positivists, all knowledge of facts comes from sense experience narrowly construed, without theoretical additions. Statements of observations are supposed to be expressed in atomic statements, or “protocol sentences” of the most primitive data we have.

The theories of science exist to explain and predict the occurrence of such observations. The entities posited by the theories, as I have said, need not exist in themselves; they may only serve to facilitate predictions. The philosopher’s job is to produce a system of logic that can be used to construct such theories and justify their inferences. This is, in effect, an ideal logical language, and it’s precisely what Russell and Whitehead had tried to formulate. What’s happening is the positivists are trying to take advantage of the great logical revolution that started with Frege and was brought to a fairly high level by Russell and Whitehead; to take this new logic and use it now in science or clarify science. All scientific claims should, in principle, prove to be reducible to claims about the most basic science, hence physics; in this sense, science itself should be unified. Perhaps we can’t do it yet; perhaps right now we’re unable to see how biological claims can be reduced to chemical claims, which can be reduced to physical claims. But in principle, we should be able to do that; so the positivists were also physical reductionists by an large.

(To be continued…)