The dominant philosophy in modern physics is instrumentalism. Physical theories are considered to be instruments for organising, explaining, and predicting empirical phenomena. This philosophy is adopted almost unconsciously by most working physicists. Doing so enables them to neglect metaphysical questions about the ontology of their fundamental physical theories, and to concentrate, instead, upon developing their mathematical formalisms for purposes of practical applicability. String theory, of course, is the ultimate upshot of this philosophy. The growth of such instrumentalism can be traced back to the popularity of positivistic ideas at the conception of quantum theory, and to the full-blown incorporation of modern academic science into the post-World War II capitalist economic system. The capitalist economic system requires the division of labour (the principle of specialisation) for the maximisation of the productivity of the entire system, hence academic science itself has become intensely specialised. There are, of course, some scientists who fight against this trend, one of whom was the late Eduard Prugovecki. Chapter 12 of Prugovecki's ambitious 1992 monograph 'Quantum Geometry', from which the following passage is taken, constitutes a sustained polemic against such instrumentalistic philosophies in modern physics:
While advocating, as the undisputed leader of the Copenhagen school, his peculiar mixture of positivism, realism, and existentialism, Bohr unfortunately did not anticipate the long-range effects of his teachings on all those in the future generations of physicists who lacked the philosophical training or the sophistication required to distinguish between subtle philosophical nuances...and their gross over-simplifications. Such physicists condensed Bohr's entire philosophy into simplified enunciations of the principles of complementarity, wave-particle duality and the purportedly “classical nature” of the “apparatus”, and simply ignored the rest. Indeed, what Karl Popper calls the “third group of physicists”, who emerged right after World War II, and soon became the overwhelming majority, is described by him as follows: “It consists of those who have turned away from discussions [concerning the confrontation between positivism and realism in quantum physics] because they regard them, rightly, as philosophical, and because they believe, wrongly, that philosophical discussions are unimportant for physics. To this group belong many younger physicists who have grown up in a period of over-specialization, and in the newly developing cult of narrowness, and the contempt for the non-specialist older generation: a tradition which may easily lead to the end of science and its replacement by technology.” (Popper, Quantum Theory and the Schism in Physics, p. 100). Upon labeling the attitude of this “third group of physicists” a form of instrumentalism, Popper goes on to say: “But this instrumentalism, this fashionable attitude of being tough and not standing for any nonsense – is itself an old philosophical theory, however modern it may seem to us. For a long time the Church used the instrumentalist view of science as a weapon against a rising science ... [as can be seen in the] argument with which Cardinal Bellarmino opposed Galileo's teachings of the Copernican system, and with which Bishop Berkeley opposed Newton. ... Thus instrumentalism only revives a philosophy of considerable antiquity. But modern instrumentalists are, of course, unaware that they are philosophizing. Accordingly, they are unaware of even the possibility that their fashionable philosophy may in fact be uncritical, irrational, and objectionable – as I am convinced that it is.”
What Popper doesn't add is that modern philosophers have also, for the most-part, adopted an instrumenalistic interpretation of modern science and physics. This conveniently enables them to believe that they can investigate metaphysical and ontological questions independently of science and physics. The effect of 20th century philosophy was to professionalise the discipline, and to transform it into an academic career. 20th century philosophers, in general, failed to grapple with the serious questions raised by 20th century science, and instead attempted to rope-off a piece of academic territory which they could call their own, which didn't require them to learn the mathematical techniques of modern science, and which was relatively safe from invasion by other academics.
In an age of excessive academic specialisation, philosophers should be the people taking a general overview of things, the people capable of unifying the disparate disciplines, the people capable of speaking, with authority, on both the science, the economics, and the social issues associated with, for example, the global warming debate. Instead, most philosophers are diligently pursuing their careers, seeking to publish only in their own house journals, seeking only to impress their peers, seeking only to address questions considered to lie within their accepted territory.