---
title: "Deductive-nomological model"
chunk: 4/6
source: "https://en.wikipedia.org/wiki/Deductive-nomological_model"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:43:33.815064+00:00"
instance: "kb-cron"
---

== Covering action ==
Through lawlike explanation, fundamental physics—often perceived as fundamental science—has proceeded through intertheory relation and theory reduction, thereby resolving experimental paradoxes to great historical success, resembling covering law model.  In early 20th century, Ernst Mach as well as Wilhelm Ostwald had resisted Ludwig Boltzmann's reduction of thermodynamics—and thereby Boyle's law—to statistical mechanics partly because it rested on kinetic theory of gas, hinging on atomic/molecular theory of matter.  Mach as well as Ostwald viewed matter as a variant of energy, and molecules as mathematical illusions, as even Boltzmann thought possible.
In 1905, via statistical mechanics, Albert Einstein predicted the phenomenon Brownian motion—unexplained since reported in 1827 by botanist Robert Brown.  Soon, most physicists accepted that atoms and molecules were unobservable yet real.  Also in 1905, Einstein explained the electromagnetic field's energy as distributed in particles, doubted until this helped resolve atomic theory in the 1910s and 1920s.  Meanwhile, all known physical phenomena were gravitational or electromagnetic, whose two theories misaligned.  Yet belief in aether as the source of all physical phenomena was virtually unanimous.  At experimental paradoxes, physicists modified the aether's hypothetical properties.
Finding the luminiferous aether a useless hypothesis, Einstein in 1905 a priori unified all inertial reference frames to state special principle of relativity, which, by omitting aether, converted space and time into relative phenomena whose relativity aligned electrodynamics with the Newtonian principle Galilean relativity or invariance.   Originally epistemic or instrumental, this was interpreted as ontic or realist—that is, a causal mechanical explanation—and the principle became a theory, refuting Newtonian gravitation.  By predictive success in 1919, general relativity apparently overthrew Newton's theory, a revolution in science resisted by many yet fulfilled around 1930.
In 1925, Werner Heisenberg as well as Erwin Schrödinger independently formalized quantum mechanics (QM).  Despite clashing explanations, the two theories made identical predictions.  Paul Dirac's 1928 model of the electron was set to special relativity, launching QM into the first quantum field theory (QFT), quantum electrodynamics (QED).  From it, Dirac interpreted and predicted the electron's antiparticle, soon discovered and termed positron, but the QED failed electrodynamics at high energies.  Elsewhere and otherwise, strong nuclear force and weak nuclear force were discovered.
In 1941, Richard Feynman introduced QM's path integral formalism, which if taken toward interpretation as a causal mechanical model clashes with Heisenberg's matrix formalism and with Schrödinger's wave formalism, although all three are empirically identical, sharing predictions.  Next, working on QED, Feynman sought to model particles without fields and find the vacuum truly empty.  As each known fundamental force is apparently an effect of a field, Feynman failed.  Louis de Broglie's waveparticle duality had rendered atomism—indivisible particles in a void—untenable, and highlighted the very notion of discontinuous particles as self-contradictory.
Meeting in 1947, Freeman Dyson, Richard Feynman, Julian Schwinger, and Sin-Itiro Tomonaga soon introduced renormalization, a procedure converting QED to physics' most predictively precise theory, subsuming chemistry, optics, and statistical mechanics.  QED thus won physicists' general acceptance.  Paul Dirac criticized its need for renormalization as showing its unnaturalness, and called for an aether.  In 1947, Willis Lamb had found unexpected motion of electron orbitals, shifted since the vacuum is not truly empty.  Yet emptiness was catchy, abolishing aether conceptually, and physics proceeded ostensibly without it, even suppressing it.  Meanwhile, "sickened by untidy math, most philosophers of physics tend to neglect QED".
Physicists have feared even mentioning aether, renamed vacuum, which—as such—is nonexistent.  General philosophers of science commonly believe that aether, rather, is fictitious, "relegated to the dustbin of scientific history ever since" 1905 brought special relativity.  Einstein was noncommittal to aether's nonexistence, simply said it superfluous.  Abolishing Newtonian motion for electrodynamic primacy, however, Einstein inadvertently reinforced aether, and to explain motion was led back to aether in general relativity.  Yet resistance to relativity theory became associated with earlier theories of aether, whose word and concept became taboo.  Einstein explained special relativity's compatibility with an aether, but Einstein aether, too, was opposed.  Objects became conceived as pinned directly on space and time by abstract geometric relations lacking ghostly or fluid medium.
By 1970, QED along with weak nuclear field was reduced to electroweak theory (EWT), and the strong nuclear field was modeled as quantum chromodynamics (QCD).  Comprised by EWT, QCD, and Higgs field, this Standard Model of particle physics is an "effective theory", not truly fundamental.  As QCD's particles are considered nonexistent in the everyday world, QCD especially suggests an aether, routinely found by physics experiments to exist and to exhibit relativistic symmetry.  Confirmation of the Higgs particle, modeled as a condensation within the Higgs field, corroborates aether, although physics need not state or even include aether.  Organizing regularities of observations—as in the covering law model—physicists find superfluous the quest to discover aether.
In 1905, from special relativity, Einstein deduced mass–energy equivalence, particles being variant forms of distributed energy, how particles colliding at vast speed experience that energy's transformation into mass, producing heavier particles, although physicists' talk promotes confusion.  As "the contemporary locus of metaphysical research", QFTs pose particles not as existing individually, yet as excitation modes of fields, the particles and their masses being states of aether, apparently unifying all physical phenomena as the more fundamental causal reality, as long ago foreseen.  Yet a quantum field is an intricate abstraction—a mathematical field—virtually inconceivable as a classical field's physical properties.  Nature's deeper aspects, still unknown, might elude any possible field theory.
Though discovery of causality is popularly thought science's aim, search for it was shunned by the Newtonian research program, even more Newtonian than was Isaac Newton.  By now, most theoretical physicists infer that the four, known fundamental interactions would reduce to superstring theory, whereby atoms and molecules, after all, are energy vibrations holding mathematical, geometric forms.  Given uncertainties of scientific realism, some conclude that the concept causality raises comprehensibility of scientific explanation and thus is key folk science, but compromises precision of scientific explanation and is dropped as a science matures.  Even epidemiology is maturing to heed the severe difficulties with presumptions about causality.  Covering law model is among Carl G Hempel's admired contributions to philosophy of science.

== See also ==
Types of inference

Deductive reasoning
Inductive reasoning
Abductive reasoning
Related subjects

Explanandum and explanans
Hypothetico-deductive model
Models of scientific inquiry
Philosophy of science
Scientific method

== Notes ==