Portrait of Wittgenstein

Wittgenstein and Scientific Knowledge

The fundamental questions that we wish Prof. Wittgenstein had answered are these:
  1. What is the status of scientific knowledge?
  2. Is it possible to draw philosophical conclusions from science?

Science: Realists vs Positivists

Ignoring everything else, there are two philosophies of science: ``realist'' and ``positivist''. The realist regards science as a way of increasing our knowledge about the world, and eventually hopes that it might lead us to discover the entities of which the world is made and the laws they obey. The positivist rejects concepts like `` the laws of nature'', and sees science as a way of collecting factual knowledge, and inventing theories that fit it.

Realism is, in a sense, the natural or pre-philosophical point of view. In its extreme forms it has been given the label ``naive realism'' -- naive, that is, from the point of view of the sceptical philosopher. To the realist it is perfectly natural to speak of the ``discovery'' of the roundness of the earth, of the atomic constitution of matter, of Maxwell's laws, and so on. If one can look into a room and see what is in there, why can't one similarly look into nature? Performing an experiment and opening a door are not essentially different. And as for theoretical knowledge: to a realist there is no sharp distinction between theoretical and experimental knowledge. Maxwell's laws can be confirmed by experiment just as can the existence of atoms, or the curvature of the earth.

Positivism is the sceptical response to realism. The positivist raises doubts about the entities that scientists regularly theorise about (fields, wave functions, particles etc). Such entities have come and gone throughout the history of science -- surely they will continue to do so. How, then, can one ever regard the current favorites as being in any sense true? Tomorrow they will have been replaced by something utterly different. In other words, the standard positivist argument involves making a sharp distinction between data and theory, and then attacking the realist's induction from data to theory: there is no unique theory to explain any finite set of data. Thus we will in principle never be able to say we have ``found the true theory'', since there will always be other theories, perhaps fundamentally different ones, that can explain the same data. Examples of many curves fitting a few data points often crop up here.

Philosophy: Realists vs Idealists

This dispute is a mirror of ``realist-idealist'' dispute, between those who believe that the world exists independently of anyone's perceiving it, and those who don't. The arguments on the two sides of this great divide are extremely similar to those of the scientific realist-positivist dispute. The realist defends the existence of the world as if that were the only possible viewpoint of a sane man. The idealist/sceptic first makes a distinction between ``sense-data'' and ``reality'', then criticises the realist for inferring an external world from what is really just an array of sensations. Taken to its logical conclusion, this argument leads inescapably to solipsism -- nothing outside one's ``inner life'' can be said to exist. Descartes followed this path of doubt and was able to eliminate everything in the world except himself: cogito ergo sum . Unfortunately, it is generally agreed, his subsequent rebuilding operation is a failure. This sort of viewpoint was certainly held well into the 20th century (eg by Russell, The Problems of Philosophy , p 12)

Wittgenstein vs The Rest

Wittgenstein took the collapse into solipsism very seriously. When Descartes claims to have doubted everything that can be doubted, and to be left with cogito , the kernel of his philosophy, Wittgenstein would dismiss even that by pointing out that he has yet to doubt his knowledge of language: once that doubt is included in the program of reduction, the Cartesian sceptic will be silent for ever.

Now that language has been mentioned, however, Wittgenstein has a new turn to add to the argument. How do words acquire meaning? Is the sceptic's rampant use of doubt sanctioned by the meaning of the word? Is the possibility of illusion really a ground for making a systematic distinction between our experience of the world and the world itself? Wittgenstein's new idea was that one should look to real language to answer questions about the meaning of words. What is ``doubt''? Look at ordinary (i.e. non-philosophical) language to see how the word is used, and there will be your answer. Carrying out this exercise, Wittgenstein demonstrated exhaustively that many philosophical problems arose from philosophy's redefining words, and then using its own definitions. In the case of ``certainty'' and ``doubt'', for example, it is clear that in ordinary use these words have rough and ready context-dependent criteria for being used. The actual word ``doubt'' in English is not universally applicable: if a child says of his own finger: ``I doubt if that's part of me'', we will correct him. The sceptical philosopher's ``doubt'' is a much stronger word, applicable to anything that cannot be shown, with philosophically absolute certainty, to be true. In this sense it is therefore a different word -- a technical term of philosophy -- ``p-doubt'' say, and the fact that p-doubt is capable of being applied to everything tells one something about the concept of p-doubt, but not a lot about anything else, particularly the existence or otherwise of the world. (Though it might reflect upon it's p-existence.)

Applying a similar kind of argument to the distinction between sense-data and reality, Wittgenstein points out that people learn what a tree is by being shown trees, not tree sense-data. The tree sense-datum is irrelevant (a ``private object'') and does not bear on anything. The possibility of illusion is there, of course, but there are criteria for deciding what constitutes an illusion. These criteria work for most people. Those for whom they fail are called ``mad'' and are widely disregarded. This is how things are!

The conclusion of this Wittgensteinian purge is that philosophy (or at least metaphysics) should take natural language as its starting point, and proceed from there. This eliminates the ornate metaphysics of the past, and in this sense it achieves the goal of logical positivism. Unlike logical positivism, however, it does not eliminate everything else at the same time: no natural language has precedence over any other, and the philosopher has no right to dictate to any of them.

Back to science

Armed with such an anti-philosophy, we may return to the scientific realism-positivism issue. Sense data are experiments, ideas about the world are theories, and the positivist uses Cartesian scepticism to pry the two apart and claim that theories are but imaginings of the scientist. What, then, corresponds to natural language? The body of scientific practice and language. However this is a more complicated situation than that of the realism-idealism argument. We may use the established practice of science as our frame of reference, but no one talks only science: science co-exists (parasitically) with natural language. In order to evaluate the arguments of the positivist and realist we have to take science and the ordinary language in which it is embedded, and use the combination as the ``natural language''.

Let us approach the first of our two initial questions: what is the status of scientific knowledge? Does it give us access to reality? As before we can discount the claims of the positivist: his p-doubt is of no relevance to the issue. However we may have a hard time with the realist too. Although science and ordinary language are partially mingled, they are largely separate (there are non-scientists). Words such as ``real'' are ordinary language words (as the realist uses them). It is clear what is meant by ``Unicorns are real'', but what is meant by ``Electrons are real''? It seems to me that the only sensible way to proceed is to take the criteria of ``reality'' in ordinary unscientific language, and apply them unaltered to scientific entities. I.e., something is real if, given a definition of it, you can actually go out and find objects that meet that definition. Now we apply this to scientific objects:

  1. Bacteria, other galaxies, etc. The lens, whether as part of a camera, telescope, or microscope, has become part of the ordinary process of seeing. We can therefore say that E. Coli, M31, etc really do exist. [Note 0]
  2. A wave function. How do you find a wave function? In some formulations of quantum mechanics there are no wave functions. Furthermore, you can only detect a particle, not the wave function that put it there. I do not see any way of saying that a wave function is "real" in the normal sense of the word.
  3. An electron. Here we have a problem with the way electrons are defined: if they are the things that make a light come on when you hit the switch, cause TV screens to glow, etc etc, then they certainly can be detected and do really exist. If they are are defined as point-like leptons whose only properties are mass, charge, and spin 1/2, then they can't be shown to exist, since in the future we may be able to explain things without reference to such objects.
It is in the third category that we find most scientific objects: we can define them in experimental terms, in which case they certainly are real, or we can define them in terms of the current theory, in which case they are not [Note 1] . Bacteria and wave functions mark the extremes of the spectrum [Note 2] .

Scientists vs Philosophers

Now the big question: can we draw philosophical conclusions from science? Of course we can't. For example, science can't possibly answer the traditional philosophical question "Is my sensation of red the same as yours?" . Or take the mind-body problem. Traditionally the argument has been: is matter different from mind, if so then what exactly is mind, and if not then how come they feel so different? One answer is physicalism, according to which mental events are in fact just brain events, and so words like ``happiness'' can be reduced to neurophysical descriptions of processes in the brain. Hence there is no such thing as ``mind''. From the Wittgensteinian point of view, this suggestion is absurd, because the fact that science might enable us to find brain processes that correspond to the word ``happiness'' is irrelevant to the meaning of that word in ordinary language, and hence can't help us to clarify its meaning. Of course, the idea that the mind-body problem is just a linguistic one might be unacceptable to some scientists and philosophers: they want to find the reality underlying our use of words. Wittgenstein would contend that the only reality is that grounded in language [Note 3]: if one wishes to reject language as a foundation then the problem of sceptical doubt arises again.

We therefore conclude that since science is essentially a different language from ordinary language, the question of the ``reality'' of its entities does not have a definite answer: it depends on how (e.g. in which language) you define them. Although we have followed Wittgenstein in rejecting the sceptical attack on realism, we have by no means embraced realism. Hence we would say it is absurd to suggest that scientific discoveries might have a bearing on the problem of free will and determinism, the mind-body problem, or any other philosophical dispute [Note 4]. These are questions about ordinary language, not scientific language. Science is not the arbiter of the meanings of the words of ordinary language.

For more, see Brian Carver's Wittgenstein homepage
Copyright © Mark Alford (1986,1998)
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