“And then there's the joke in which a young man told his mother he would become a Doctor of Philosophy and she said, “Wonderful! But what kind of disease is philosophy?”
~Steven Pinker in “The Blank Slate”
Philosophers and physicists, especially those working on fundamental questions of nature, have a difficult relationship. I know a lot of physicists who use the word philosophy as an insult, and even those who have sympathy for the quest of the philosopher tend to give them a hard time.
And understandably so. I’ve heard talks by philosophers about the “issue” of infinities in quantum field theory who had never heard of effective field theory. I’ve heard philosophers speaking about Einstein’s “hole argument” who didn’t know what a manifold is, and I’ve heard philosophers talking about laws of nature who didn’t know what a Hamiltonian evolution is.
But on the other hand, I’ve met remarkably sharp philosophers with the ability to strip away excess baggage that physicists like to decorate their theories with, and go straight to the heart of the problem. No wonder the relation between both sides can be uncomfortable.
This has left me wondering what is the role of philosophy in physics, or in modern science more general.
I will admit that I have a limited attention span for philosophical arguments. To begin with, philosophers (as apparently everybody in the humanities) have the annoying tendency to throw around names rather than proper definitions. The introduction of a cosmology paper in philosophy style would not contain the Friedmann equations, but instead two conflated paragraphs on the Friedmannian paradigm and its contextual appropriation of the cosmological principle, subsequently adapted as the concordance model.
Leaving aside the name-throwing and over-abundance of multi-syllable words, the issue of lacking definitions is a deep one for me. If somebody can’t write down a definition for expressions they are referring to, I lose interest. Because then their whole argument is in the end just empty words. I am interested in verbal arguments only to the point that they precede the construction of a mathematical model.
Having said that, here is where philosophy plays a role in physics: To develop these verbal arguments that have not yet been possible to cast in a more stringent form. This means though that when science progresses, when our knowledge expands, the room where philosophy is useful inevitably shrinks. The role of the observer in quantum mechanics, horizons in general relativity, or infinities in quantum field theory might once have been philosophical question. They no longer are. Presently popular topics for philosophers in physics seem to be the nature of time and the multiverse. Personally I think these are already topics that are close enough to existing theories that they can and should be cast into a mathematical language. Topics that are further off presently existing theories, and still more clearly playground for philosophers, are for example free will or the role of mathematics in science in general.
This tension between philosophers and scientists doesn’t only exist in physics. Another area where you find frequent displays of this confrontation is neuroscience. Consciousness used to be the field of the philosophers, but no longer so. Yet, philosophers are slow to get off the turf.
A recent display of this can be found in a NYT opinion piece that discusses “famous thought experiments” by philosophers. One of these famous arguments that philosophers discuss to make a living seems to be based on confusing the brain perceiving the color red as a result of photons of a certain wavelength hitting the retina, with the brain knowing about the process of perceiving the color. You might be forgiven for confusing knowledge about perception with the perception itself if you didn’t know anything about the brain, but in the last decade we have learned a lot about how the brain is wired and processes input. Or at least some of us have.
It seems clear to me that consciousness and self-awareness are areas that philosophers will have to clear in the soon future. That is correct: I don’t think there’s anything particularly mysterious about self-awareness, and nothing about it that we won’t be able to understand with some more research on complex systems and neural networks.
But what about science at large? Does this mean that we have a philosophy of the gaps much like we have a god of the gaps, filling in the spaces where currently knowledge is missing, but inevitably on the retreat?
For most of science this is a thorny question (previously discussed here), that being whether or not there is an end to the knowledge about nature that mankind can gather. It’s a question I don’t know how to answer.
But regardless of the answer to this question, for as long as there will be conscious beings thinking they will always be left with the question whether there are limits to what they can think of. And a more pragmatic, though related, question is how science works and how it progresses. These I believe are areas where philosophy will always play a role: to analyze the process of thought and inquiry, and its realization in the scientific endeavor. And as long as we have fundamental questions about nature, it is good to keep philosophers around to catalyze the process of making soft science into hard science. Even if they are sometimes a little annoying.