|The general model of reductionism: namely that all social phenomena can be "reduced" to physics and chemistry explanations.|
“All things in the end are reduced to material being, i.e. to matter itself.”— Jean Meslier (1729), The Testament (§68, pg. 372)
The following are three main types of general reductionism:
● Cartesian reductionismThe following are noted types of human-sphere concerned reductionism:
● Gibbsian reductionism
● Newtonian reductionism
The following are noted reductionists: Johann Goethe (1796), Auguste Comte (1854), Friedrich Engels (1882), Albert Weiss (1925), Richard Feynman (1985), Libb Thims (1995), and [add].
Anecdotes | Party conversations
In 1968, Dean Wooldridge gave some type of physics-based reductionism anecdote.
In 2010, David Brin, in reflection (Ѻ) on circa 1971 Caltech party conversation, gave the following rather humorous take in reductionism, from different points of view:
“Sometimes philosophical or scientific insights come from an event that’s not very profound, like a party. I remember at Caltech: sure there were a lot of smart people around, some of my roommates and even some professors. I remember one fellow, a pompous fellow, he was saying ‘physics’ is the most basic of all the sciences. After all it’s how the universe works, right? Well, one of my housemates was a mathematician, and he wasn’t about to let that go. He said ‘all your physical laws, your quote on quote laws, are just mathematical models, applied to the real world.’ As if the real world didn’t matter too much? (It didn’t to him). And he seemed quite smug and satisfied that he had demolished this earlier statement until a philosopher, a guy who had become a philosophy major, came up and he said, ‘well look, you know Bruce, that all of your mathematical derivations come from the axioms, the fundamental premises, the basis upon which you base your formulas. And Bertrand Russell proved that those can be almost arbitrary. It’s all a matter of philosophical choice, where you start from. Philosophy is the most basic and general of things.’ And he seemed to have everybody convinced, until a psychologist said ‘but wait a minute, where does all your philosophy come from? It’s all rooted in psychology. It’s been proved long ago. Plato just manufactured all that stuff, based upon his own impulses. You could psychoanalyze him and derive it all. It’s all mental.’ At which point, a biologist came up and said ‘and where does all this mental stuff come from? It’s all in the brain, a biological organ, that evolved over time, to certain Darwinian needs. Obviously, it’s all rooted in biology.’ To which the chemist said ‘and what is biology? It’s just colloidal chemistry. I mean look down at the level of the cell, the level of the DNA, it’s all chemistry. It’s more basic than any of your convoluted organs and all that.’ At which point, the physicist said ‘are you all done now?”
A more recent anon circular truncation of the argument is as follows: (Ѻ)
“Every biologist is, at heart, a chemist.
And every chemist is, at heart, a physicist.
And every physicist is, at heart, a mathematician.
And every mathematician is, at heart a philosopher.
And every philosopher is, at heart, a biologist.”
Reductionism, in physics, according to Freeman Dyson (1995), as cited by Steven Weinberg, is the effort to “reduce the world of physical phenomena to a finite set of fundamental equations.” 
Comte | Hierarchy of sciences
In 1854, French philosopher Auguste Comte, in his System of Positive Polity: or System of Sociology, gave the following so called “hierarchy of the sciences”, according to which they all are, at bottom, dependent on astronomy: 
“The conception of the hierarchy of the sciences from this point of view implies, at the outset, the admission, that the systematic study of man is logically and scientifically subordinate to that of Humanity, the latter alone unveiling to us the real laws of the intelligence and activity. Paramount as the theory of our emotional nature, studied in itself, must ultimately be, without this preliminary step it would have no consistence. Morals thus objectively made dependent on Sociology, the next step is easy and similar; objectively Sociology becomes dependent on Biology, as our cerebral existence evidently rests on our purely bodily life. These two steps carry us on to the conception of Chemistry as the normal basis of Biology, since we allow that vitality depends on the general laws of the combination of matter. Chemistry again in its turn is objectively subordinate to Physics, by virtue of the influence which the universal properties of matter must always exercise on the specific qualities of the different substances. Similarly Physics become subordinate to Astronomy when we recognise the fact that the existence of our terrestrial environment is carried on in perpetual subjection to the conditions of our planet as one of the heavenly bodies. Lastly, Astronomy is subordinated to Mathematics by virtue of the evident dependence of the geometrical and mechanical phenomena of the heavens on the universal laws of number, extension, and motion.”
In this framework, as summarized by German physicist Karl Pearson, in Comte's hierarchy of science, morals is the "supreme science", about which paramount is the "theory of our emotion nature", which must be tied into: sociology, biology, chemistry, physics, astronomy, and lastly mathematics as the "language", in Willard Gibbs famous phrasing, of it all, respectively, in one unified theory.  This position is fortified by the fact that Goethe—the highest ranking universal genius—considered his 1796 "moral symbols" theory, sociology and biology based on physical chemistry (physics + chemistry), or affinity chemistry as it was called in Goethe's time, to be his greatest work or "best book".
Alternatively, to put the above into a different perspective, previously, in his 1842 Positive Philosophy, Comte characterized four main branches of the science of the universe, referring to everything as a type of physics: celestial physics, terrestrial physics, organic physics, and human physics, as follows: 
“Now that the human mind has grasped celestial and terrestrial physics, mechanical and chemical, organic physics, both vegetable and animal, there remains one science, to fill up the series of sciences or observation—social physics. This is what men have now most need of; and this it is the principal aim of the present work to establish.”
The earliest reductionism views stem from Greek circa 475BC Leucippus-Democritus atomic theory school who held that everything in the universe is but atoms moving in a void. American science historian Albert Helden summarizes atomic reductionism as such: 
“Matter can be subdivided only to a certain point, at which only atoms (that which cannot be cut) remain. The world is made up of atoms moving in the void. Atoms differed from each other only in size and shape, and different substances with their distinct qualities were made up of different shapes, arrangements, and positions of atoms. Atoms were in continuous motion in the infinite void and constantly collided with each other. During these collisions they could rebound or stick together because of hooks and barbs on their surfaces. Thus, underlying the changes in the perceptible world, there was constancy (atoms were neither created nor destroyed); change was caused by the combinations and dissociations of the atoms.”(add)
|A typical reductionism view of the sciences, arranged from soft (sociology, psychology, biology) to hard (chemistry, physics) the former (softer) argued to be reducible to the latter (harder), with mathematics being the language of the hardest.|
Pattee | Quantum mechanical reductionism
In 1967, American theoretical physicist Howard Pattee gave the following reductionism model—as cited by Lila Gatlin in her 1972 “Reductionist/Antireductionist Controversy” chapter section: 
“Although the chemical bond was first recognized and discussed at great length in classical terms, most physicists regarded the mature of the chemical bond as a profound mystery until Heitler and London qualitatively derived the exchange interaction [see: exchange force] and showed that this quantum mechanical behavior accounted for the observed properties of valency and stability. On the other hand, it is not uncommon to find molecular biologists using a classical description of DNA replication and coding to justify the statement that the living cells obey the laws of physics without ever once putting down a law of physics or showing quantitatively how these laws are obeyed by these processes.”(add discussion)
French philosopher Rene Descartes (1596-1650), who sought to reduction of all phenomena to matter in motion, is often cited as the pioneer of the reductionist point of view. Descartes' model was expanded on by English physicist Isaac Newton in his Principia (1867), wherein the idea of a ‘clockwork universe' was furthered.
English philosopher Francis Bacon (1581-1626) is said to have further the reductionism views of Descartes, advocating the view that nature’s so-called watchworks can best be understood by breaking them down into parts. 
| Left: A Descartes-Bacon view of reductionism: the premise that to understand nature—or a watch—one must break it down to its parts (generally atoms in the case of nature). Right: |
The general view of reductionism holds that all of nature—chnopsological (biological) nature specifically—can be reduced to the known laws of physics and chemistry; or generally reduced down to the level of the atom, an entity comprised of: protons, neutrons, and electrons, as shown above, and their behaviors.
In 1882,German social scientist Friedrich Engels surmised that:
“One day we shall certainly ‘reduce’ thought experimentally to molecular and chemical motions in the brain.”
English geneticist Francis Crick (Of Molecules and Men, 1967), supposedly, is a reductionist spokesperson with his comment: 
“So far everything we have found can be explained without effort in terms of the standard bonds of chemistry—the homopolar bond, the van der Waals attraction between non-bonded atoms, the all-important hydrogen bond, and so on.”
Reductionist / Anti-reductionist Controversy
See main: Reductionist anti-reductionist debateIn 1972, American biophysicist Lila Gatlin devoted a chapter section to the “Reductionist—Anti-reductionist Controversy”, in which she summarizes as being on the question of whether or not life can be reduced to the “laws of physics and chemistry”.
Thinkers generally adverse to the possibility or conclusion that their behavior and actions of humans can be reduced to pure physics and chemistry, often times will turn to models such as emergence, complexity theory, holism, synergy, chaos theory, far-from-equilibrium theory, bifurcations, unpredictability, among others to argue that where as reductionism and determinism may apply at the sub-cellular level, the do not apply at the larger level of ecosystems and societies.  In this sense, the terms “reductionism” and “determinism” are generally types of derogatory categorical labels used by theorists against or adverse to these views.
|Left: The four tiers of reductionism from the cover of the 2010 book Promises and Limits of Reductionism in the Biomedical Sciences, giving the depiction that marriage can be explained, underlyingly, in terms of pure physics and chemistry.  Right: Science fiction writer David Brin on a CalTech party on which science is the most basic.|
An alternative definition, by American ecosystem engineer Robert Ulanowicz, who seems to be against the premise of reductionism (in favor of, it seems: emergence and process biology, mixed with hues of transcendence), defines reductionism as an ideology which holds that "the only proper direction of scientific exploration is analytical, i.e. that explanations of larger phenomena are to be sought exclusively among events at smaller scale". 
American philosopher of science Ernest Nagel, in his The Structure of Science (1961), according to Steven Weinberg, gives the “paradigmatic example of the reduction of one theory to another”. 
The following books, e.g. Arthur Koestler (1969), and articles, according to Michael Foley (1990), are said to be representative of the debate on whether organisms are reducible or not to mechanical properties: 
● Simon, Michael A. (1971). The Matter of Life: Philosophical Problems of Biology (pgs. 144-67). Yale University Press.
● Koestler, Arthur and Symthies, John R. (1969). Beyond Reductionism: New Perspectives in the Life Sciences. Hutchinson.
● Hull, David L. (1974). Philosophy of Biological Science (pgs. 125-41). Prentice-Hall.
● Grene, M. (1971). Interpretations of Life and Mind: Essays around the Problem of Reductionism. Routledge.
● Wisdom, J.O. (1972). “Must a Machine be an Automaton?” (abs), in: Biology, History and Natural Philosophy (editors: Beck and Yourgram) (pgs.291-98). Publisher.
● Deutsch, Karl W. (1951). “Mechanism, Organism and Society; Some Models in Natural and Social Science” (abs), Philosophy of Science, 18(3):230-52.
● Gardner, M. (1981). Mathematical Circus (pgs. 102-10). Harmondsworth.
● Anon. (1982). “Why Can’t a Computer be More Like a Man?”, Economist, Jan 9.
|A 2013 hierarchy of sciences diagram by Eric Fisk.|
The following are related quotes:
“Physical science will not stop short of a reduction of the universe and all it contains to the basis of mechanics; in more concrete terms, to the working of a machine.”— Carl Snyder (1903), New Conceptions in Science (Ѻ)
“I would like to again impress you with the vast range of phenomena that the theory of quantum electrodynamics describes: It’s easier to say it backwards: the theory describes all phenomena of the physical world except the gravitational effect, the thing that holds you in your seats (actually, that’s a combination of gravity and politeness, I think), and radioactive phenomena, which involve nuclei shifting in their energy levels. So if we leave out gravity and radioactivity (more properly, nuclear physics), what have we got left? Gasoline burning in automobiles, foam and bubbles, the hardness of salt or copper, the stiffness of steal. In fact, biologists are trying to interpret as much as they can about life in terms of chemistry, and as I already explained, the theory behind chemistry is quantum electrodynamics.”— Richard Feynman (1985), QED: the Strange Theory of Light and Matter 
“Since human organizations are staffed by human beings, and since human beings are biological organisms, it might be argued that my research problem is indeed biological. And since biological organisms are constructed from molecules, and those molecules from atoms, and the atoms from elementary particles—all obeying the laws of quantum mechanics—it might even be argued that research on human organizations is merely a rather baroque branch of physics.”— Howard Pattee (1973), Hierarchy Theory: the Challenge of Complex Systems 
“One hears it said that biology is just a branch of chemistry, which is turn just a branch of physics.”— Paul Davies (1988) 
“Most of the useful concepts of chemistry … are imprecise. When reduced to physics, they tend to disappear.”— Roald Hoffmann (1988), “Under the Surface of the Chemistry Article” 
“The reductionist attitude provides a useful filter that saves scientists in all fields from wasting their time on ideas that are not worth pursuing.”— Steven Weinberg (1992), Dreams of a Final Theory (pg. 64)
“Present knowledge rests on the foundation of physics, which will be used to support our contentions herein. Accordingly, we admit the postulate that reality may ultimately be reducible to certain elementary particles. It is they eventually make up everything, from the most banal material things to the most exalted ethereal ideas. These particles, named fermions, are of two kinds: leptons and quarks. The former, of which electrons are the most prevalent example, are very antisocial in that they exist alone; while the latter are quite sociable and so are always found in groups. Quarks combine to form protons and neutrons, which make up the atomic nucleus. As the fundamental units of matter, various combinations of atoms, composed of nuclei and revolving electrons, build up all material structures, from molecules and cells, to planets and stars. In between, there is the realm of human society with its own kind of individual and collective entities.”— Paris Arnopoulos (1993), Sociophysics (pg. 22); 2005 edition (pgs. xlviii)
“The ideal of the 11th/17th century physicists was to be able to explain all physical reality in terms of the movement of atoms. This idea was extended by people like Descartes who saw the human body itself as nothing but a machine. Chemists tried to study chemical reaction in this light and reduce chemistry to a form of physics, and biologists tried to reduce their science to simply chemical reactions and then finally to the movement of physical particles. The idea of reductionism which is innate to modern science and which was only fortified by the theory of evolution could be described as the reduction of the spirit to the psyche, the psyche to biological activity, life to lifeless matter and lifeless matter to purely quantitative particles or bundles of energy whose movements can be measured and quantified.”— Seyyed Nasr (1993), A Young Muslim’s Guide to the Modern World 
“Science allegedly explains things reductively—by analysing them into components. For example, the resistance of a wall to being penetrated or knocked down is explained by regarding the wall as a vast aggregation of interacting molecules. The properties of those molecules are themselves explained in terms of their constituent atoms, and the interactions of these atoms with one another, and so on down to the smallest particles and most basic forces. Reductionists think that all scientific explanations, and perhaps all sufficiently deep explanations of any kind, take this form.”— David Deutsch (1998), The Fabric of Reality 
|Left: a humorous take on reductionism in romance. Right: Auguste Comte's 1854 ordering of the sciences, according to which everything reduces chemistry, physics, astronomy, and ultimately to mathematics.|
1. Mazzocchi, Fulvio. (2008). “Complexity in Biology: Exceeding the Limits of Reductionism and Determinism Using Complexity Theory”, European Molecular Biology Organization, 9(1): 10-14.
2. Gatlin, Lila L. (1972). Information Theory and the Living System (pgs. 14-16). Columbia University Press.
3. Mirowski, Philip. (1989). More Heat than Light: Economics as Social Physics, Physics as Nature’s Economics (pg. 45). Cambridge University Press.
4. Ulanowicz, Robert E. (2009). A Third Window: Natural Life beyond Newton and Darwin (pg. 22). Templeton Press.
5. Frenay, Robert. (2006). Pulse: the Coming Age of Systems and Machines Inspired by Living Things (pg. 8). Farrar, Straus and Giroux.
6. Feynman, Richard. QED: the Strange Theory of Light and Matter (pgs. 7-8). Princeton University Press.
7. Atomism (Albert Van Helden) – RSC.org.
8. (a) Pattee, Howard H. (1967). “Physical Problems of Heredity and Evolution”, in: Towards a Theoretical Biology (editor: C.H. Waddington) (contents). Publisher.
(b) Gatlin, Lila L. (1972). Information Theory and the Living System (pg. 15). Columbia University Press.
9. Deutsch, David. (1998). The Fabric of Reality (pg. 19). Penguin Books.
10. Regenmortel, Marc and Hull, David. (2010). Promises and Limits of Reductionism in the Biomedical Sciences (pg. 162). Wiley.
11. Comte, Auguste. (1854). System of Positive Polity: or Treatise on Sociology, Instituting the Religion of Humanity, Volume 4 (pg. 162). Longmans, Green, 1877.
12. Pearson, Karl. (1892). The Grammar of Science (text) (pg. 509). Adam and Charles Black, 1900.
13. (a) Davies, Paul. (1988). The Cosmic Blueprint (pg. 98). Simon & Schuster.
(b) Hsieh, Ching-Yao, and Ye, Meng-Hua. (1991). Economics, Philosophy, and Physics (pg. xxvi). M.E. Sharpe.
14. Reductionism quotes – GoodReads.com.
15. Pattee, Howard. (1973). Hierarch Theory: the Challenge of Complex Systems (pg. 3). G. Braziller.
16. (a) Nagel, Ernest. (1961). The Structure of Science (§:The Reduction of Theories, pgs. 338-45). Harcourt, Brace & World.
(b) Weinberg, Steven. (1992). Dreams of a Final Theory: the Scientist’s Search for the Ultimate Laws of Nature (pgs. 40, 286) Random House.
17. (a) Hoffman, Roald. (1988). “Under the Surface of the Chemistry Article”, Angewandte Chemie, 27:1597-1602.
(b) Weinberg, Steven. (1992). Dreams of a Final Theory: the Scientist’s Search for the Ultimate Laws of Nature (pg. 43). Random House.
18. (a) Dyson, Freeman. (1995). “The Scientist as Rebel”, The New York Review (pgs. 31-33), May 25.
(b) Weinberg, Steven. (date). “Reductionism Redux” (pdf), Publisher.
19. Foley, Michael. (1990). Laws, Men and Machines: Modern American Government and the Appeal of Newtonian Mechanics (pg. 252). Routledge, 2014.
● Auyang, Sunny Y. (1999). “Beyond Reductionism in Biology”, Talk presented in the Department of History and Philosophy of Science, University of Sydney, May; CreatingTechnology.org.
● Jones, Richard H. (2000). Reductionism: Analysis and the Fullness of Reality. Bucknell University Press.
● Peterson, Randall T. (2008). “Chemical Biology and the Limits of Reductionism (abs)”, Nature Chemical Biology, 4: 635-38.
● Reductionism – Wikipedia.