In the famous “Epigram on Sir Isaac Newton”, the poet Alexander Pope wrote:
Nature and nature’s laws lay hid in night:
God said, Let Newton be! and all was light.
In reply to this, J. C. Squire (1884-1958) continued:
It did not last: the Devil howling “Ho!
Let Einstein be!” restored the status quo.
In the twentieth century, the picture of our world has changed entirely. In the past, the notions of space and time were accurate and robust, allowing a proper and robust cognitive organisation of object. The evidence of space-time order would enable us to set a causal structure that regulates the external world. Scientists were looking for a simple and strong theory to explain the regularity of the world, whereas this world would have to conform to the mathematical language.
New description of the world
Then, when Einstein’s relativity and quantum theory had appeared in the scientific panorama, the assumptions of classical physics, perfectly intuitive and in accord with the most common perception of the world, were deconstructed one by one.
Some strange things happen in this new description of the world. There is no precise measure of time and space: a quantum object has no defined properties (we can only detect an electron in a specific volume of space, regardless of the instrument we use).
There is no objectivity about the experiment: an experiment on a quantum object is always altered by the observer. There is no static universe: our universe is, according to Hubble, constantly expanding. Stop reading for a moment and imagine something that is constantly expanding. We are living in such space!
Moreover, there are fewer practical experiments and more mental experiments to provide conclusions about the world. Einstein used abstract examples to develop both special relativity theory and general relativity. Schrödinger developed his famous example of the cat to illustrate quantum mechanics theory.
Success and truthfulness of science
New methods, new technology, a new description of the world, new theories… If these kinds of revolutions happen recurrently throughout the history of science, how can we believe in our present theories? How can we be sure that even in the case of their empirical success, they will not be replaced by other, completely different theories in the future? And how can we still believe in our current theories? How can we believe in the progress of science?
It seems that the only reply is that we cannot believe in the truth of our scientific system; we can only suspend our judgement about the success of empirical experiments and have an instrumental approach to our world.
But how can we explain the empirical success of science? It would be impossible to explain the marvelous success of science and its capacity to predict novel phenomena if our scientific theories were not at least approximately true descriptions of the world! For example, how could prediction of the precise position of the planet Neptune be possible if the Newtonian theory were not true? And, more generally, when can we say that a theory with success is also true?
Realism versus antirealism
Those questions have been a central issue in the philosophical debates between realists and antirealists. In general, realists hold that we are justified in believing in our scientific theories and that the success of our current best theories is evidence of the claims that scientific theories are true (or approximately true).
For example, Einstein published his theory about relativity in 1915, then he patiently waited for a solar eclipse in 1919 that could disprove his general relativity about space, depending on how light travels through space. Well, since then the relativity theory was confirmed and Einstein’s name became a synonym for “genius”. Since then, common physics has changed.
What the scientific realist view holds is that it would be an incredible coincidence, a huge miracle, if relativity theory is false in this explanation of phenomena. And we do not believe in miracles, do we? This argument concludes that, as the philosopher Putnam says, in light of the widely accepted predictive success of theories, we can believe in them.
On the other hand, this argument does not convince antirealists. The opposing view to realists suggests that, given that many past successful theories have turned out to be false, we do not have reason to believe in success as an indicator of truth.
Science as approximation to reality, not truth
This argument, called the pessimistic meta-induction on the history of science, is a real challenge for realists because it invokes a long list of successful theories in the past that are no longer accepted as true. And, by induction, our best scientific theories will turn out to be false in the same way.
Think again about the classical Newtonian mechanics. It is still taught at school, and NASA still uses it to send spacecraft to other planets. But, if you ask a scientist, he will probably reply that it is a good approximation in the limit of slow speed, but is not enough to describe very fast (the speed of light) and microscopic (quantum objects) phenomena.
According to the antirealist position, this is a clear demonstration that science must be regarded as false from a future prospective. In this view, quantum mechanics and relativity are only better approximations to reality, not approximations to the truth! We are blind about the opportunity to know the world in itself.
So, what about scientific investigation of the truth? If we agree with Einstein, we think that the scientist has a strong will and wants to understand the reality around him. If, on the other hand, we agree with S. Hawking, we do not know what reality is; thus, we do not ask for correspondence between theory and reality. In particular, he says:
All I’m concerned with is that the theory should predict the results of measurements. Quantum theory does this very successfully. It predicts that the result of an observation is either that the cat is alive or that it is dead. It is like you can’t be slightly pregnant: you either are or you aren’t.
In the end, realism and antirealism, understood in this light, provide different views of understanding scientific methods. They each illuminate certain features of scientific activity, and it seems that you either believe in scientific theories or do not. However, it is indubitable that spending money on scientific research that we do not believe in is like buying a dress that does not fit us!
Lisa Zorzato is a first-year PhD student of philosophy at the University of Tartu.