In the past, both Philosophy and Science were one. However, because of the vastness of Science, it was cut off. I am inclined to go along the same line of thinking, but, is there a way to merge both disciplines once again?

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    Hi, welcome to philosophy SE. Science split off from philosophy not just due to vastness. There are significant differences in methodology, scince is much more definitive in its formulations and standards of acceptance, much of it is also empirical, while philosophy isn't, at least not in the same sense. Philosophy often serves as incubator of disciplines while they demarcate their domain and develop specific methodologies for it. Remerging would not only be impractical but counterproductive. – Conifold May 23 '16 at 22:12
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    @Conifold To me, science is applied philosophy, and I'm not alone in thinking that. Day to day inference, induction, and other forms of reason are used. Moreover picking the question is often a deeply philosophical undertaking: which helps us understand the universe more, which new knowledge would be more true? Just because scientists learn formulas rather than the texts of philosopher's doesn't mean they are separated. Perhaps more scientists should study philosophical works! – James May 24 '16 at 1:19
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    They never were separated. Many scientists like to think and teach that they are different, but they are still just another philosophical school of thought, another world view. Read "Quantum Physics and Ultimate Reality: Mystical Writings of Great Physicists" Edited by Michael Green – Swami Vishwananda May 24 '16 at 5:29
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    I would say that modern science is a single school of philosophy, like Platonism. It takes several great philosophical questions as answered, but beyond that, it remains philosophy. Feyerabend may be right in spirit, but even he recognizes the pressure to have an orthodoxy is real. And orthodoxy can be pursued only under dogma, whether or not it is the right thing to do. – user9166 May 24 '16 at 22:28
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    What exactly do you mean by "science" and by "philosophy"? – Geremia May 26 '16 at 21:45

The question isn't whether they should be re-merged, but whether they were ever as separable as we thought they were in the first place. Since the beginning of the 20th century, philosophers of science have been working on the demarcation problem, that is the problem of how to determine what qualifies as science and what doesn't. The constant obstacle that they were facing was that every criteria for determining whether a field of inquiry was scientific or not ended up being either too strong or too weak: Some criteria were such that psychology, string theory or the theory of evolution didn't qualify as science. Other criteria ended up including creationism and astrology. No clear cut demarcation of what constituted science and what didn't was found.

By the second half of the 20th century, some philosophers of science started proposing that such a demarcation was impossible. Using results from logic, the nature of our language, and an analysis from the history of science, it looked like science was not the clearly defined perfectly objective enterprise we thought it was.

W.V.O Quine, concludes in his paper "Two Dogmas of Empiricism" that it is not possible to separate science from metaphysics, and so scientists can never escape philosophy. At the end of his paper he states that:

"Physical objects are conceptually imported into the situation as convenient intermediaries not by definition in terms of experience, but simply as irreducible posits comparable, epistemologically, to the gods of Homer . . . For my part I do, qua lay physicist, believe in physical objects and not in Homer's gods; and I consider it a scientific error to believe otherwise. But in point of epistemological footing, the physical objects and the gods differ only in degree and not in kind. Both sorts of entities enter our conceptions only as cultural posits."

Paul Feyerabend in his book "Against Method" makes the claim that science is an essentially anarchic enterprise, and there is no such thing as the scientific method, but instead that "anything goes" in science.

So to your question: Are philosophy and science mergeable today?

Quine and Feyerabend would reply that science and philosophy never separated in the first place, we just fooled ourselves into thinking they did.

Also see my reply to the question: Why have those scientists who rejected or opposed philosophy, still succeeded? - in brief: Scientists are doing philosophy, its just that most of the time they don't know or admit that they are doing so.

Some of the answers below contradict mine, mentioning either explicitly (John Forkosh) or implicitly (Jo Wehler) the verificationist theory of meaning as a clear demarcation between science and philosophy. The verificationist theory of meaning has been refuted for good, by challenges and criticisms coming from its own camp (Hempel, Quine,...). I alluded to this in my first paragraph, with verifiability being one of the criteria that failed.

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    this is absolutely the right answer! many philosophers (but not all, obviously ) started out in math or physic and then switched. Hilary Putnam, Huw Price, etc. – user20153 May 24 '16 at 21:49
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    Don't forget Wittgenstein, who progressively moved all the way over from engineering -- I think he was a doctoral student in aeronautics. – user9166 May 25 '16 at 2:50
  • @jobermark indeed he was. I don't know enough about his phil.sci to be able to include him in my answer. – Alexander S King May 25 '16 at 17:00
  • Demarcation efforts failed because they were based on unrealistic presupposition that there should be bright lines of separation, the backlash then made the opposite soritic mistake of seeing no difference between a handful and a heap because they are joinable by intermediates philosophy.stackexchange.com/questions/31942/… And early Quine would say not that science never separated from philosophy but that it did such a good job of it that it is ready to subsume philosophy on its own terms. – Conifold May 25 '16 at 21:43
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    @Conifold but then what of something like contemporary cognitive science or physics circa Newton? aren't situations like that proof that sometimes the problem of telling the heap from the handful is real? – Alexander S King May 25 '16 at 21:46

I do not know a well-known scientist who at the same time is a professional philosopher.

Can you imagine a contemporary professor who has a chair in a science department and also in the philosophical department of a renowned university? There are only a few scientist who have a PhD in physics or biology and also in philosophy. Possibly you find some neuroscientists who are active in both science and philosophy, e.g. Gerhard Roth from Germany.

From a more general point of view I see a big difference between philosophy and science: Different than philosophy science builds on empirical data. And science always strives to check a scientific theory against empirical data.

Today philosophy of nature does not contribute any longer to scientific progress. And philosophy of science exists as a meta-theory, but often it is not taken seriously by working scientists.

In my opinion, todays philosophers are not familiar with the results of modern science; not even with the fundamental theories from 20th century. E.g. the concept of spacetime as developed by the Theory of Relativity has hardly entered into the philosophical discussion in the field of metaphysics.

Summing up: Philosophy and science do not merge today. And I do not see any reason why they should do so in the future.

Added. To avoid any misunderstanding due to language: By "science" I mean "natural science" in my answer.

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    Excuse the late-night, partial response. But I consider this an absurd calumny. From Mach, Kuhn, Maudlin, Prigogine, Penrose,,,to innumerable others, the only division between "physics" and "metaphysics" is the one created by the division of labor and time constraints produced by modernism and Capital. How quickly we forget! To say, as many scientist once did, that "physics is our best description of reality" is a metaphysical statement, just an ill-informed one. The line dividing the "publishable" works of physics and metaphysics is best addressed by a Marxist analysis. – Nelson Alexander May 25 '16 at 2:27
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    You are all still just being bigoted. Philosophy and Psychology is such a common overlap that there is joint PhD program for it at Yale. Zizek's chair is in a dept of both Sociology and Philosophy. There is a continuum of sciences, not Physics and Everything Else. – user9166 May 25 '16 at 2:43
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    @jobermark Which from Zizek's works do you consider scientific? See his bibliography at en.wikipedia.org/wiki/Slavoj_%C5%BDi%C5%BEek_bibliography – Jo Wehler May 25 '16 at 5:33
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    @JoWehler Not the point "Can you imagine a contemporary professor who has a chair in a science department and also in the philosophical department of a renowned university" Well, I don't have to imagine, if Sociology is a science. If not, you would need to make the case. So historically, this happens, and right now, this happens. Unless you are a physics bigot. – user9166 May 25 '16 at 14:28
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    @jobermark In order to remove any misunderstanding due to language: By "science" I mean "natural science" like the OP. – Jo Wehler May 25 '16 at 15:15

In the past, both Philosophy and Science were one.

There's always been a distinction between and classification of the sciences.

Classification of the Sciences

Ancient Classification

For example, the Aristotelian-Boethian classification has lasted for many centuries. Boethius, following Aristotle, wrote that the "Speculative sciences may be divided into three kinds: physics, mathematics, and metaphysics" (§II of Boethius's De Trinitate):

  1. Physics [i.e., natural philosophy] deals with that which is in motion and material.
    [ens mobile or "mobile/changeable being"]
  2. Mathematics deals with that which is material and not in motion.
    [∵ mathematical objects, "mathematicals," do not move or change]
  3. Metaphysics* deals with that which is not in motion nor material.
    *in the Aristotelian sense: the study of "being qua being;" more properly called "metascience," it is what today is called the "philosophy of science" because metascience/metaphysics studies being in general, whereas the particular sciences study specific beings (e.g., biology studies living beings, etc.).

Ancient & Modern Classifications Compared

Modern, mathematical physics is a "mixed science" or "intermediate science" (scientia media), taking its material principles from physics (natural philosophy) and its formal principles from mathematics. The science in Aristotle's time that did this was astronomy; thus,

ancient physics : ancient astronomy :: modern philosophy : modern science

For more information on the scientia media, see:

  1. Expositio Posteriorum lib. 1 l. 41 n. 3
    …some sciences are purely mathematical, those, namely, which abstract according to reason from sensible matter, as geometry and arithmetic; but other sciences are intermediate, namely, those which apply mathematical principles to sensible matter, as optics applies the principles of geometry to the visual line, and harmony, i.e., music [acoustics], applies the principles of arithmetic to sensible sounds.…
  2. Super Boethium De Trinitate q. 5 a. 3 ad 6
    …there are three levels of sciences concerning natural and mathematical entities. Some are purely natural and treat of the properties of natural things as such, like physics, agriculture, and the like. Others are purely mathematical and treat of quantities absolutely, as geometry considers magnitude and arithmetic numbers. Still others are intermediate [the scientia media], and these apply mathematical principles to natural things; for instance, music [acoustics], astronomy, and the like. These sciences, however, have a closer affinity to mathematics, because in their thinking that which is physical is, as it were, material, whereas that which is mathematical is, as it were, formal. For example, music [acoustics] considers sounds, not inasmuch as they are sounds, but inasmuch as they are proportionable according to numbers; and the same holds in other sciences. Thus they demonstrate their conclusions concerning natural things, but by means of mathematics. …
  3. In II Physica lect. 3 n. 7 [164.]
    Those sciences are called intermediate sciences which take principles abstracted by the purely mathematical sciences and apply them to sensible matter. For example, perspective applies to the visual line those things which are demonstrated by geometry about the abstracted line; and harmony, that is music [acoustics], applies to sound those things which arithmetic considers about the proportions of numbers; and astronomy applies the consideration of geometry and arithmetic to the heavens and its parts.
  4. Summa theologica II-II q. 9 a. 2 ad 3
    As stated above (Question 1, Article 1), every cognitive habit regards formally the mean through which things are known, and materially, the things that are known through the mean. And since that which is formal, is of most account, it follows that those sciences which draw conclusions about physical matter from mathematical principles, are reckoned rather among the mathematical sciences, though, as to their matter they have more in common with physical sciences: and for this reason it is stated in Phys. ii, 2 that they are more akin to physics.

From this site, which mentions historian of physics Pierre Duhem's continuity thesis (opposed to Kuhn's "rupture" or "paradigm shift" thesis):

From footnote †7 on pg. 24 of St. Thomas Aquinas's Division and methods of the sciences, a commentary on Boethius's De Trinitate questions V and VI, translator Armand Maurer mentions these articles relating Scholasticism to empiriological sciences like modern physics.

The growth in modern times of empiriological science, as distinct from philosophy in its formal object and method, renders impossible a physical theory that would be applicable in a univocal way to both. Such a theory, which denies the distinction between philosophical and empiriological analysis, has been proposed by R. Nogar, "Toward a Physical Theory," The New Scholasticism 25 (1951), 397-438.

J. Weisheipl proposes a return to St. Thomas and St. Albert for "a unifying physical theory" that would include both the philosophy of nature and the empirical or experimental sciences. For Weisheipl these constitute one specific discipline, both materially and formally. However, he regards the sciences employing mathematical principles as really distinct from natural philosophy. See J. Weisheipl, The Development of Physical Theory in the Middle Ages; "The Relationship of Medieval Natural Philosophy to Modern Science: The Contribution of Thomas Aquinas to Its Understanding," in Science. Medicine and the Universities 1200-1550. Essays in Honor of Pearl Kibre (= Manuscripta 20 [1976]), pp. 181-196; idem, Introduction to The Dignity of Science. Studies in the Philosophy of Science Presented to William Humbert Kane OP (= The Thomist 24 [1961]).

In the same spirit, see C. De Koninck, "The Unity and Diversity of Natural Science," in The Philosophy of Physics, ed. V. E. Smith, pp. 5-24; W. A. Wallace, "St. Thomas's Conception of Natural Philosophy and its Method," in Studi Tomistici. La philosophie de la nature de saint Thomas d'Aquin, ed. L. Elders, pp. 7-27; idem, Causality and Scientific Explanation [cf. idem, Review of Metaphysics 27:3 (March 1974)].

For further discussions of this topic, see E. McMullin, "Philosophies of Nature," The New Scholasticism 43 (1969), 29-74; J. Compton, "Reinventing the Philosophy of Nature," The Review of Metaphysics 33 (1979), 3-28; E. McMullin, "Compton on the Philosophy of Nature," ibid., pp. 29-58; idem, "Is There a Philosophy of Nature?" Proceedings of the International Congress of Philosophy, Vienna, 1968, 4: 295-305.

Classification of the Modern Sciences

C. S. Peirce (1839-1914), the greatest American philosopher-scientist IMHO, did some excellent work on the classification of the modern sciences (cf. this).

cf. the traditional division of philosophy to that of Christian von Wolff (1679-1754)

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  • You have invested much effort in your historical survey and its many references. - What is your opinion: Does the classification of Aristotle referring to the two issues "matter" and "motion" allow any insight in todays physics, mathematics, or metaphysics? – Jo Wehler May 26 '16 at 23:11
  • @JoWehler Yes, I believe so. Modern physics is a scientia media. Modern mathematics could (for the most part) be classified under the ancient heading, although some of what is mathematics today is really logic (e.g., "mathematical logic"). Modern metaphysics is idealist/nominalist and doesn't seem to have much to do with the philosophy of science, which is what Aristotle et al. understood metaphysics (i.e., metascience) to be. – Geremia May 26 '16 at 23:20
  • @JoWehler I forgot to mention: C. S. Peirce (1839-1914), the greatest American philosopher-scientist IMHO, did some excellent work on the classification of the modern sciences (cf. this). – Geremia May 26 '16 at 23:24
  • Concerning mathematics I disagree with Aristotle: Seen from an abstract perspective, mathematics is a game with free concepts and free rules which conform to logic. Rules and concepts are ideas. Kinematical terms like motion or physical terms like matter do not apply to ideas. These terms are not just false in the context of ideas, they are simply senseless. – Jo Wehler May 27 '16 at 11:29
  • @JoWehler By "mathematics," you seem to mean what Peirce calls "Mathematics of Logic" (cf. the table here), which he classified as one order of mathematics, alongside the more "Aristotelian" mathematics like arithmetic (discrete math) and geometry (continuous math). – Geremia May 27 '16 at 17:22

Separation between subjects is largely a matter of administrative convenience.

Some of the problems traditionally seen as philosophical arise from science, or are made sharper or solved by scientific progress. For example, over the past few years some problems with our understanding of probability have been solved by work on the Everett interpretation of quantum theory conducted by physicists like David Deutsch and philosophers like David Wallace, see



Other philosophy concerns problems are not commonly considered by science.

Some are philosophers studying one another's work. This if often completely sterile as the study becomes divorced from the problem the original philosophers were trying to solve, as explained by Karl Popper in "Philosophical problems and their roots in science" in "Conjectures and Refutations".

Another kind of issue is methodological, moral and political issues, like the following. What sort of experiments should scientists do and why? Should scientists aim to discover objective reality, or are they limited to studying appearances? What sort of system of political economy should we adopt? A lot of good material on these issues has been written by people rejected and despised by academic philosophers, like Karl Popper, Ayn Rand and Ludwig von Mises.

I think that the sort of merging between philosophy and science many people have in mind proposes something like getting rid of all the methodological parts of philosophy by studying what people actually do. This would make progress on such issues difficult or impossible because what people do is not necessarily the same as what they actually do. The sort of person who wants this typically can't be bothered with critical discussion of their ideas, habits and practices and wishes that people would just obey him without question. In his imagination the standard practice would be whatever he wants it to be. Such people would find it easier to dominate and control others if philosophy ceased to exist as separate from science. I am not saying that you are in this category, but many people are in this category.

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  • When was Karl Popper "rejected and despised by academic philosophers" ? He's come up in every single academic Philosophy of Science course I've seen. – Alexander S King May 24 '16 at 19:07
  • Yes, Popper does come up, almost always as a straw man with his positions distorted beyond recognition. And his stuff is usually followed by people like Kuhn who are said to have refuted Popper, when in reality Popper refuted Kuhn. In addition, he never comes up in epistemology courses despite having solved major problems in epistemology, of which his philosophy of science was just a part. If you ignore 90% of what a philosopher said and caricature the rest, that can hardly be considered anything other than contempt and rejection. – alanf May 24 '16 at 19:48
  • "when in reality Popper refuted Kuhn" - can you elaborate? – Alexander S King May 24 '16 at 20:06
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    See the title essay of "The Myth of the Framework", the introduction to "Realism and Aim of Science", Popper's reply to Kuhn in "The Philosophy of Karl Popper" edited by Schilpp and his contribution to "Criticism and the growth of science" edited by Lakatos and Musgrave. Kuhn made false statements about Popper's position, e.g. - that he was a naive falsificationist or somehow equivalent to one. Kuhn's philosophy of science was also no good as it said there was no rational way to choose between competing theories, which was wrong. – alanf May 24 '16 at 20:57

Despite some preceding remarks to the contrary, I'd hazard to say they're not (completely) mergeable, and furthermore haven't been since the scientific(=experimental) method. Scientists have an extra constraint on the kinds of thoughts they can entertain, which philosophers often ignore, and sometimes even pooh-pooh. And that constraint's summed up by the verifiability theory of meaning, particularly the empirical formulation, e.g., http://en.citizendium.org/wiki/Verifiability_theory_of_meaning .

Any concept introduced by science must be experimentally observable; in particular, that means constructively observable: you have to provide instructions for the construction of an apparatus that measures/observes whatever it is you're talking about. And then those instructions correspond to the meaning/semantics of your (observable) concept. Even gedanken experiments, that aren't meant to be actually performed, are characterized by the detailed design of a hypothetical experimental apparatus. And I've yet to see philosophers provide such construction instructions for apparatus that measure, say, love/freedom/justice/faith/you-name-it. Philosophy just isn't characterized or bound by this kind of constraint.

An interesting scientific exception is the quantum mechanical wavefunction itself, where only it times its complex conjugate corresponds to an experimentally observable probability. So what's the "wavefunction" itself, i.e., how do you interpret it? That question's sometimes the subject of debate. The simple answer is that the wavefunction's just not an element of reality -- not a scientific element of reality. But philosophers, not bound by experimental constraints on meaningful concepts, are free to debate its "meaning".

To elaborate this a little, Max Jammer, in "The Philosophy of Quantum Mechanics", goes to some length defining a (scientific) theory as what he calls a "partially interpreted formal system". And I wish I could find the exact page again, but he then somewhere says that a "perfect theory" is one where every (scientific=measurable) concept is represented by a formal term, and, conversely, every formal term has a (scientific) interpretation, i.e., a one-to-one "completely interpreted formal system". Thus, our preceding wavefunction is part of the formalism, but has no scientific=measurable interpretation. So it's not a Jammer-perfect scientific theory. But, to repeat myself, philosophers can nevertheless debate its meaning, without ever suggesting what apparatus they'd construct to measure that meaning. And scientists who engage in such debates are behaving philosophically. But that doesn't mean they're philosophers. They ultimately return to their scientific sensibilities, making sure they always have an experiment in mind corresponding to any concept they're talking about.

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  • The verifiability theory of meaning was completely discredited by the 1960s. Notably the refutation of verificationism didn't come from people opposed to it (e.g. mystics, romantics, etc...) but from its own camp, from people very sympathetic to the scientific world view such as Carl Hempel and W.V.O Quine. – Alexander S King May 31 '16 at 15:43
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    @AlexanderSKing Well, even if discredited philosophically (though I'm surprised to hear Quine rejects it), it surely isn't discredited in physics (where it's more typically called operationalism). So if one discipline rejects it while the other accepts it, that's another pretty strong indication the two disciplines aren't "mergeable". To be completely accurate, physics doesn't unambiguously accept operationalism (and philosophy.stackexchange's spellcheck doesn't even accept my spelling:), but it's actively debated -- the meaning of an observable is given by the apparatus used to measure it. – John Forkosh Jun 2 '16 at 0:48
  • Except that string theory already challenges the concept of meaning in physics. (Most) Physics can ignore metaphysics because it is working within a well established paradigm. But more importantly physics isn't the only natural science. There are other sciences that haven't yet reached the level of maturity of physics, where metaphysical speculation is still very relevant. Lawrence Krauss, a leader among the "philosophy is useless crowd" actually admits that other natural sciences still need philosophy, and that as recently as 40 years ago even cosmology had use for metaphysics. – Alexander S King Jun 2 '16 at 0:57
  • @AlexanderSKing It sounds to me like you're going off on a tangent about metaphysics as though it's relevant (which it's not) to the "mergeable" question at hand. Moreover, I'm not denying the usefulness of metaphysics, and certainly not saying physics "ignores" (your word above) it. Indeed. operationalism is itself a metaphysical position. To further follow your tangent line, I'd say metaphysics is mainly useful to physicists insofar as it focuses your intuition trying to formulate theories. But it's ultimately experimental verifiability (or conversely, falsifiability) of a theory that counts – John Forkosh Jun 2 '16 at 1:13
  • metaphysics is a branch of philosophy. If metaphysics can be merged with physics (or any other natural science), then philosophy can be merged with physics (or any other science). – Alexander S King Jun 2 '16 at 1:35

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