What is the intersection of Physics & Philosophy?

Question

(I've already asked this question on Meta, but as one answer (by Joseph Weissman) pointed out this is already a philosophical question; so I thought it worth asking here).

I've asked a number of physics questions in philosophy, none of which included equations, and are determined by the larger, and as far as I can see philosophical questions about the natural world; traditionally, ie in Maxwells time, it would be called Natural Philosophy; and in fact Thomson & Tait (Thomson was knighted as Lord Kelvin, and in whose honour the natural scale of temperature is designated in Kelvin) brought out a book called The Principles of Natural Philosophy; this is a long and honourable tradition.

Qustions for example on Entropy, disorder, time and space. For example this question on entropy at time close to the Big Bang, or this one about the direction of time.

Yet people often attack these questions as not belonging to Philosophy.

A quick perusal of the SEP shows that there are many topics that it covers; for example:

1. Action at a distance in Quantum Mechanics

2. Being and Becoming in Modern Physics

3. Boltzmans work in Statistical Physics

4. Quantum Approaches to Consciousness

5. The role of Decoherence in Quantum Mechanics

Further, Oxford University has a faculty named Physics and Philosophy which is housed in the Humanities; from which course description one can see that:

The physics corresponds to the more theoretical side of the standard three-year Oxford Physics course while the philosophy focuses on modern philosophy, particularly metaphysics and the theory of knowledge.

They acknowledge a 'bridging subject', the Philosophy of Physics which interperlotes between the two disciplines.

and their interests lie broadly in:

interests in classical space-time theories, foundations of classical statistical mechanics, quantum mechanics, quantum field theory and quantum gravity.

These are, when suitably interpreted, the interests of the classical Milesian Materialists.

However, on this site, it seems that questions of Physics which are broadly philosophical in the above sense seem to be outlawed, as being not considered as philosophy. In my personal opinion, for what its worth, Philosophy ought to be considered a broad school, one looks at Aristotle for example who covered a broad swathe of scientia (knowledge) covering ethics, politics, and natural philosophy as well as metaphysics.

So the question here is how does one determine when a question of physics is philosophical enough, by what authority or by what criteria can we designate them? There is the obvious possibility that an inter-disciplinary subject such as this will offend the purists of both schools - still as the above examples show, it is possible.

Answer 1

Aristotle would clearly say the intersection of philosophy and physics is physics. We have taken the view later that science is something else, and we have encoded a couple criteria for what is and isn't science which we attribute vaguely to Karl Popper and Thomas Kuhn.

From an attempt to synthesize this modern tradition and classical tradition, we might look at science as the part of philosophy which is attached to a specific paradigm in the sense of Kuhn, or for which falsifiability is still undetermined, in the sense of Popper. In a vague sort of way, these mean the same thing. Establishing falsifiability is done within a paradigm, and the falsification of a theory truly and fully embraced by its paradigm is reason for a crisis in the science, if only a minor one.

The idea that such attachment creates a science seems clear from the existence of classical Economics, which is really just Utilitarian philosophy phrased as a descriptive paradigm. It seems clear that Utilitarianism remains philosophy, and that Economics is still a science.

At the same time, huge parts of philosophy fall into no science. Physicists do not know more about whether space is really quantizable than we do, only what discrete space would and would not mean for their current theories. A philosopher rejecting all of those theories, or holding them all as provisional, is still free to approach the topic from a more purely intuitive basis.

And we see periods in important sciences where the main questions devolve back into philosophy. Look at discussions of atomism at the rise of thermodynamics. Newton did not consider gravitation consistent with atoms, but the new theories of heat seemed much clearer in those terms. The result was clearly less science than philosophy, so much so that the 'father' of thermodynamics had to change fields back and forth to get any mindshare at different stages of the debate.

Further to the degree that a every given science contains competing paradigms that have not yet come to peace with one another, like relativity and quantum dynamics in physics, or the tensions between cognitive science and ordinary psychology, there are still questions in every science that are not strictly delineated out by any paradigm. But even questions within each of the competing paradigm are information about comparing them.

So the distinction between physics and philosophy has to be taken as a matter of degree. Questions fully embedded in a paradigm seem clearly scientific, and silly for outsiders to address without appropriate training, but questions between them, or questions about meanings or framings of them are less so.

The single primary contradiction here is analytic philosophy itself. To a large degree it is a paradigmatic discipline, and the work within it is not accessible to anyone outside the paradigms in question. I would argue the details of modern logic and analytics are no longer philosophy, but belong as minority voices in what used to be philology and is now largely linguistics or mathematics.

Answer 2

To answer the meta-question first: For purposes of this site, questions that deal with primarily with physics are probably most usefully handled by the physics stack-exchange, both in terms of reaching the experts best able to answer them, and in terms of being found by other users with similar questions.

In terms of the broader philosophical question of whether physics is philosophy: Philosophy is the mother of the sciences, and many disciplines, not just physics, had their origins within philosophy. Once a discipline, however, gains a well-defined methodology and objective decisioning standards, it is no longer a philosophy.

There still may be valid philosophical questions just outside the boundaries of what physics can determine, but from a quick survey of your questions, it seems like many of them dealt primarily with things that physics likely has a defined answer to, or at least a theoretical way to reach a defined answer.

Answer 3

This is indeed a philosophical question and a debated one.

First, note that science was called 'natural philosophy' a few centuries ago so one could argue that science is actually part of philosophy, but let's not quibble and take philosophy in the modern sense of the term, which does not encompass pure science.

One of the defining characteristic of science is the confrontation of theories to experience. Perhaps a question becomes philosophical enough when it can no more be answered by direct experimental test, but by intuition and a priori analysis instead?

Wittgenstein thought the aim of philosophy is to clarify language by mean of conceptual analysis, until our claims become testable. A question would be philosophical when it's not clear what the question is exactly, and scientific when we know precisely what the question means and how to test it (that is, when philosophy has done its job). The idea was adopted later by logical empiricists.

This distinction can be extended to Kuhn's thesis: "normal" science would function inside a given paradigm, where concepts and their mapping to experimentation is well defined, but philosophical thinking would be required for paradigm change.

Things proved to be more complex than the logical empiricists thought (scientific claims are not always testable), and science and philosophy certainly overlap, but the spirit of this thesis can probably be retained: a question is philosophical enough when it demands us to clarify our concepts rather than simply apply well defined scientific concepts to a specific situation.

That puts whole parts of cutting-edge fundamental science into the realm of philosophy, but I don't think this is necessarily a problem.

If it is, here is a more restrictive approach: the aim of philosophy would be to unify different sciences together and with what Sellars calls the "manifest image of the world" (our pre-scientific representations and experiences) into a coherent, unified picture of the world. This would be done in particular through an interpretation of scientific concepts and how they relate to common experience (example: relating different notions of time) or other scientific fields (example: causation in biology, physics, ...).

There is no consensus on the role and delimitation and there might be other approaches.

Answer 4

If the scope of the question allows for philosophical answers then it is clearly philosophical. If it can only be answered acceptably from a scientific standpoint then it clearly isn't.

To put it another way, if the questions premises preclude the possibility of Kantian subjectivity regarding knowledge of time and space, ordinary language analysis, feminist critique, etc., then it is perhaps not philosophical. If Plato and Hume and Nietzsche cannot possibly bring anything to the discussion, the question might be more physics than philosophy, so to speak.

In the end, if the question is premised on the same set of assumptions about the world that one uses in the scientific investigations of physics, then as philosophers we should be on guard. One feature that distinguishes philosophy is the questioning the foundations if our world views.