This situation should not be interpreted as a deficiency, but rather as a faithful reflection of the epistemic limitations intrinsic to the subject itself. The universe is a unique system, inaccessible to controlled experimentation, and for a long time it resisted any formulation in terms of strict, predictive, and falsifiable laws. As a consequence, cosmological inquiry remained naturally intertwined with philosophy, metaphysics, and foundational reflection, a status that persisted well into the twentieth century. Even after the advent of general relativity, which provided the first consistent dynamical framework for describing the universe as a whole, cosmology continued to be characterized by a plurality of viable models with limited empirical discrimination [1,2]. * Electronic address: msaridak@noa.gr Over roughly the last three decades, however, this situation has undergone a profound transformation. The emergence of high-precision cosmological observations has altered not only the methodology of the field, but also its epistemic status. Measurements of the cosmic microwave background anisotropies [3][4][5], large-scale structure surveys [6], type Ia supernova observations [7,8], baryon acoustic oscillations [9,10], weak and strong gravitational lensing [11,12], and, more recently, gravitational-wave standard sirens [13], have collectively established cosmology as a quantitatively constrained, predictive, and internally cross-checked scientific enterprise. Today, cosmological parameters are routinely inferred with percent-level or sub-percent-level precision, and theoretical models are systematically confronted with mutually independent datasets.

As a result, contemporary cosmology now operates in a regime that differs fundamentally from its historical predecessor. Its core theoretical structures no longer function merely as frameworks for organizing qualitative narratives about the universe, but as effective, law-like descriptions whose validity can be tested, constrained, and potentially falsified. The Friedmann equations, the perturbation theory, and the statistical description of cosmic structures, now act as operational laws governing the large-scale behavior of spacetime and matter, in close analogy with the role played by dynamical laws in other mature branches of physics. From this perspective, current tensions in cosmological data, such as those involving the Hubble parameter or the amplitude of matter fluctuations, should not be viewed as signs of conceptual weakness, but rather as manifestations of a field that has attained sufficient precision to expose its own limitations and falsifiability [14].

In this work, we argue that this epistemic transformation motivates a corresponding conceptual and termino-logical reassessment. In close analogy with the historical transition from astrology to astronomy, which marked the passage from qualitative interpretation to law-based description of celestial phenomena, contemporary cosmology has effectively crossed the threshold from a logos of the cosmos, namely a rational and discursive account, to a nomos of the cosmos, understood as a law-governed description. We therefore suggest that the term cosmonomy may more accurately capture the present and emerging status of the field, emphasizing its law-based, predictive, and falsifiable character. This proposal is not intended as a revision of historical terminology, nor as a dismissal of the philosophical depth of cosmological inquiry, but rather as a conceptual clarification reflecting the maturation of the discipline.

Accordingly, the aim of this paper is not to introduce new cosmological models or observational analyses, but to examine, from a historical, epistemological, and methodological perspective, whether contemporary cosmological practice has reached a stage at which it can be meaningfully regarded as a law-based science of the observable universe as a whole. In this context, we propose the term cosmonomy as a natural descriptor of this stage, together with the corresponding term cosmonomer for the practitioner engaged in this endeavor. Whether or not this terminology is ultimately adopted by the community, we believe that reflecting on the conceptual evolution it encapsulates is both timely and instructive.

In ancient Greek thought, the term kosmos did not primarily designate a physical system governed by dynamical laws. Rather, it referred to an ordered totality: a structured whole characterized by harmony, proportion, and intelligibility. Its semantic field encompassed notions of order, arrangement, and ornament (the words cosmos and cosmetics have the same root), emphasizing coherence and completeness. In this sense, kosmos expressed the conviction that the totality of what exists is not chaotic, but ordered in a manner accessible to rational contemplation.

This conception is particularly evident in Plato’s Timaeus, where the cosmos is presented as a unified and living whole, ordered according to intelligible principles and fashioned so as to reflect mathematical harmony [15]. Here, the emphasis is not placed on dynamical evolution in time, but on ontological completeness and rational design. The cosmos is described primarily as that which is, rather than as that which evolves according to explicit laws of motion. Temporal change is acknowledged, yet it remains subordinate to a deeper metaphysical order that defines the cosmos as a finished and intelligible totality.

A closely related perspective is found in Aristotle’s On the Heavens, where the universe is treated as a selfcontained whole endowed with a privileged structure and natural places [16]. Although Aristotle introduces concepts of motion and causality, these are embedded within a teleological and qualitative framework rather than a quantitative, law-based one. Celestial motions are regular and eternal, but they are not derived from universal dynamical equations applicable across scales. Instead, the cosmos is divided into qualitatively distinct regions, each governed by its own principles, reflecting an ontological hierarchy rather than a unified dynamical system.

In both Plato and Aristotle, the cosmos is therefore not conceived as an object amenable to systematic experimentation or to mathematical law in the modern sense. Rather, it is a whole whose intelligibility arises from its ordered structure and internal coherence. Understanding the cosmos was thus primarily a philosophical task: to articulate its meaning, structure, and place within a broader ontological framework, rather than to formulate predictive laws governing its evolution.

From this perspective, the absence of the term κοσμολογία (kosmologia) in ancient Greek texts is neither accidental nor merely linguistic. It reflects a deeper epistemic reality, namely the absence of the conditions required for a law-based science of the universe as a whole. Although ancient thinkers developed sophisticated and often highly systematic accounts of the cosmos, these accounts did not, and could not, constitute a cosmology in the modern sense of a testable, predictive theory of cosmic evolution.

Instead, ancient discourse made use of the words cosmogony and cosmography, around which its treatment of the cosmos was largely organized. Cosmogony addressed the origin of the cosmos, frequently in mythological or metaphysical terms, but occasionally through rational speculation, focusing on principles of generation rather than on dynamical laws. Cosmography, by contrast, concerned the descriptive ordering of the world, mapping its structure without seeking universal equations governing its behavior. Both approaches were inherently qualitative and narrative, reflecting the epistemic tools available at the time.

It is nevertheless important to note that certain early Greek philosophical schools already entertained the idea that the cosmos unfolds according to necessity or rational order. Heraclitus, in particular, conceived the world as structured by a universal logos, while the atomists, most notably Leucippus and Democritus, maintained that nothing occurs at random, but that everything follows from necessity. These conceptions, however, remained metaphysical commitments rather than empirically grounded or quantitatively formulated laws, and therefore did not yet amount to a nomological science of the cosmos.

Crucially, the universe was understood as a unique and singular entity, lacking the repeatability and statistical accessibility required for empirical law formulation. Without the possibility of controlled variation, ensemble reasoning, or systematic observation across comparable systems, the formulation of universal laws governing the cosmos as a whole remained epistemically inaccessible. Even where regularities were identified, they were interpreted as expressions of metaphysical necessity or divine order, rather than as empirical laws subject to falsification.

From this point of view, the historical absence of cosmology should not be seen as a failure of ancient thought, but as a faithful reflection of the epistemic status of the subject itself. The cosmos, considered as a totality, lay beyond the reach of law-based treatment. Its uniqueness precluded experimental manipulation, while its immense spatial and temporal scales severely limited observational access. As a result, discourse about the cosmos necessarily remained at the level of rational reflection, philosophical interpretation, and qualitative synthesis. The cosmos could be meaningfully contemplated, but not scientifically legislated.

The epistemic situation discussed above for the cosmos as a whole stands in sharp contrast with the study of individual celestial bodies within the cosmos. The regularity of their motions made them accessible to systematic observation and, eventually, to mathematical treatment. It is in this restricted but crucial domain that astronomy first emerged as a precision science. In this section, we examine how the transition from qualitative interpretation to law-based description unfolded in the study of the heavens.

The decisive factor that enabled the study of the heavens to evolve into a law-based science was the exceptional degree of regularity exhibited by celestial phenomena. Unlike most terrestrial processes, the motions of celestial bodies display pronounced periodicity, long-term stability, and repeatability over timescales vastly exceeding those of everyday experience. These features rendered celestial phenomena uniquely amenable to systematic observation, mathematical description, and, ultimately, reliable prediction.

Already in early antiquity, the recurrence of eclipses, conjunctions, and planetary cycles made it clear that celestial motions obey stable and persistent patterns. Even in the absence of explicit physical mechanisms, such regularities could be exploited to predict future events with remarkable accuracy. This predictive success marked a crucial epistemic transition: celestial phenomena were no longer merely described or symbolically interpreted, but increasingly treated as manifestations of underlying regularities that could be encoded mathematically.

It is important to recall that, in early Greek usage, the terms αστρολογία (astrologia) and αστρονομία (astronomia) were not sharply distinguished. Historically, astrologia appears as the earlier and more general designation for rational discourse on the heavens, whereas astronomia emerged later as a more specialized term emphasizing the ordering and law-like regularity of celestial motions. In their original context, astrology denoted a rational account of the heavens, while astronomy highlighted their structured and predictable behavior. Neither term carried the metaphysical or divinatory/zodiac connotations commonly associated with astrology in modern usage. Rather, both referred, with different emphases, to what would now be recognized as a mathematical and physical study of celestial phenomena.

Thus, the gradual differentiation between astrology and astronomy reflects not a change in subject matter, but a shift in epistemic criteria. During the Hellenistic period, Greek mathematicians and astronomers, including Autolycus, Eudoxus, Callippus, Apollonius, Conon, Hipparchus, and Sosigenes, systematically formalized astronomy as a mathematical discipline. They developed geometrical models, kinematic schemes, and predictive techniques aimed at quantitatively accounting for celestial motions. Nevertheless, in parallel intellectual currents and under the influence of Babylonian astral traditions, alongside this mathematical consolidation, a bifurcation emerged between the exact, mathematical treatment of celestial motions and conjectural interpretations concerning their influence on terrestrial affairs. This distinction was articulated with particular clarity by Ptolemy, who separated the demonstrative mathematical science of the heavens, developed in the Almagest [17], from the probabilistic and interpretive framework of judicial astrology presented in the Tetrabiblos [18]. From this point onward, astronomy increasingly came to denote a discipline defined by exact prediction and empirical accountability.

At this stage, the emerging “science of the stars” remained largely descriptive in its physical interpretation. Geometrical constructions were devised to reproduce observed motions, without necessarily claiming to identify their underlying causes. Nevertheless, the very possibility of representing celestial motions through mathematical relations signaled a profound shift. Once the positions of celestial bodies could be expressed as functions of time,

the heavens ceased to be objects of qualitative contemplation and became systems governed by reproducible and testable patterns.

The key epistemic point is that repeatability made falsification possible. Predictions concerning future configurations of celestial bodies could be confronted with observation, and persistent discrepancies demanded revision of the underlying models. In this sense, the transition from astrology to astronomy was not primarily a semantic or sociological reclassification, but the emergence of a law-based description of nature grounded in regularity, predictability, and empirical constraint.

As discussed above, Ptolemy’s Almagest marks a clear stage in the transition from astrology to astronomy, in which celestial motions are treated as objects of precise mathematical calculation. Although the Ptolemaic system remained kinematic rather than dynamical, its predictive power was undeniable. Planetary positions, eclipses, and cycles could be calculated with sufficient accuracy to establish astronomy as a quantitatively reliable discipline. Such predictive control rendered celestial motions amenable not only to calculation, but also to mechanical realization, as exemplified by devices such as the Antikythera Mechanism, which physically embodied astronomical laws [19].

Despite the extraordinary achievements of ancient scholars in describing the regularities of the heavens, the decisive step toward a fully nomological science was taken in the early modern period. This transition was enabled by technological advances, most notably the invention of the telescope, which made high-accuracy observations possible, and by the formulation of Kepler’s laws, later unified within the framework of Newtonian mechanics. Kepler’s empirical laws reduced the apparent complexity of planetary motion to simple mathematical relations, while Newton demonstrated that these relations followed from universal dynamical principles. In Newtonian gravity, celestial motion is governed by equations of the form

which apply universally, independently of the specific nature or location of the bodies involved. With this development, astronomy became the first exact natural science in the modern sense. Celestial phenomena were no longer explained through ad hoc geometrical constructions or metaphysical principles, but derived from universal laws capable of unifying diverse observations within a single theoretical framework. Prediction, explanation, and falsification became inseparable components of the same enterprise. This transformation provided the epistemic justification for the term astronomia as a genuine nomos of the stars. The heavens could now be understood as obeying strict, quantitative, and universally valid laws. The significance of this achievement was not merely technical, but conceptual: it established that at least part of the natural world admits a law-based description that is both predictive and empirically testable.

Despite the success of astronomy, the extension of a fully nomological framework to the observable universe as a whole remained, for a long time, out of reach. The cosmos differs from individual celestial systems in ways that are epistemically decisive. Most importantly, it is a singular object: there is only one universe, which cannot be varied, replicated, or subjected to controlled experimental manipulation.

As a consequence, the methodological conditions that support law formulation in astronomy (repeatability, ensemble reasoning, and controlled comparison) were absent when the cosmos was considered as a totality. Even if large-scale regularities were suspected, there was no clear sense where and how they could be tested or falsified. Without access to multiple realizations or statistically independent samples, the universe could not be treated as a system governed by empirically established laws.

The emergence of the term cosmology marks an important conceptual moment in the intellectual history of the study of the universe. Nevertheless, its appearance does not signal the maturation of an already law-based science, but rather the formalization of a metaphysical domain concerned with the universe taken as a whole.

The earliest known occurrence of the word cosmology dates to the seventeenth century. In English, it is attested in Thomas Blount’s Glossographia (1656), where it is defined as a discourse concerning the world or the universe [20]. This lexical introduction is revealing: the term enters scientific and philosophical language not as the name of an established empirical discipline, but as a label for a general rational treatment of the cosmos.

The systematic introduction of cosmologia as a distinct branch of knowledge is due to Christian Wolff in the early eighteenth century. In his Cosmologia Generalis (1731), Wolff explicitly classifies cosmology as a subdivision of metaphysics, alongside ontology, rational psychology, and natural theology [21]. Within this framework, cosmology concerns the most general properties of the world as a whole, abstracted from particular physical processes and independent of empirical measurement.

This classification is epistemically significant. Cosmology is introduced neither as an extension of astronomy nor as a natural science grounded in observation, but as a rational inquiry into the world considered in its totality. Its subject matter is defined by maximal generality rather than by dynamical specificity. Accordingly, early cosmology inherits the structural features of philosophical discourse: internal coherence, conceptual clarity, and logical consistency take precedence over empirical confrontation.

At this stage, cosmology is explicitly non-empirical. The universe is treated as a necessary object of reason, not as a system governed by measurable laws. This status is not accidental, but reflects the absence of observational access to global cosmic properties. Without data capable of constraining cosmic structure or evolution, cosmology could not yet aspire to the status of a law-based science. For these reasons, discourse about the cosmos remained outside the domain of nomos and belonged instead to logos: rational reflection on the structure and meaning of the totality of existence.

The transition from metaphysical cosmology to a proto-scientific discipline begins only in the twentieth century, with the advent of relativistic gravity. General relativity provided, for the first time, a consistent theoretical framework within which the observable universe could be treated as a dynamical entity [22,23]. Cosmological models developed by Friedmann, Lemaître, and later Robertson and Walker opened the possibility of describing the large-scale structure and evolution of spacetime in explicit mathematical terms.

Nevertheless, for several decades cosmology remained only weakly constrained by observation. Although theoretical models proliferated, empirical discrimination between them was limited. Early observations, including galaxy redshift measurements and estimates of cosmic expansion, offered suggestive indications rather than decisive tests. As a result, a wide variety of cosmological scenarios coexisted, often differing in fundamental assumptions concerning geometry, matter content, and cosmic history. This period is marked by a striking plurality of models. Different cosmological solutions of Einstein’s equations were explored primarily on theoretical grounds, with observational data playing a secondary and often ambiguous role. In the absence of precise measurements, cosmological reasoning relied heavily on simplicity arguments, philosophical preferences, and internal theoretical consistency. The universe could be modeled, but not yet legislated.

Consequently, cosmology during this era occupied an intermediate epistemic position. It was no longer purely metaphysical, yet it had not acquired the methodological rigor characteristic of a mature natural science. Its status was that of a boundary discipline, situated between physics and philosophy, between mathematical formalism and conceptual speculation. This liminal character is reflected in persistent debates concerning initial conditions, global geometry, and the interpretation of cosmological solutions. Accordingly, cosmology in this period was typically presented as a late and conceptually oriented application of general relativity, often appearing as a concluding chapter in general relativity textbooks rather than as an autonomous empirical science.

With the advent of high-precision observational capabilities, cosmology gradually began to shed the intermediate epistemic status that had long characterized the field. Advances in astronomical instrumentation, survey design, and data analysis opened observational access to the universe across a wide range of physical scales and cosmic epochs, transforming what had previously been a weakly constrained theoretical enterprise into an empirically grounded science. This extended process of maturation ultimately led to a qualitative shift: cosmology moved from a largely speculative or interpretive activity toward a quantitatively testable, law-based, and datadriven description of the universe. It is this transformation, driven by the convergence of precise observations and well-defined theoretical frameworks, that forms the subject of the present section and motivates the conceptual shift discussed thereafter.

The decisive step that elevates modern cosmology from a descriptive framework to a genuinely law-based science is the existence of explicit dynamical equations governing the universe as a whole. Within general relativity, the large-scale dynamics of spacetime and matter are encoded in a compact set of equations whose domain of validity extends across the entire observable universe.

Starting from the observationally motivated assumption that the Universe is homogeneous and isotropic on sufficiently large scales (the Cosmological Principle), general relativity admits a quantitative description based on the Friedmann-Lemaître-Robertson-Walker spacetime metric

(5.1) where a(t) is the scale factor and k = +1, 0, -1 denotes closed, flat, or open spatial geometry. Within this framework, cosmic evolution is governed by the Friedmann equations

supplemented by the continuity equation,

where H = ȧ/a is the Hubble function, ρ and p denote the energy density and pressure of the cosmic fluid, and Λ is the cosmological constant. Together, these relations describe the global expansion of the universe and enable quantitative predictions for its past and future evolution once the properties of the cosmic components are specified.

Beyond the background level, cosmology admits a systematic perturbative expansion that governs the formation and evolution of cosmic structures. For scalar perturbations in the linear regime, the evolution of matter overdensity δ ≡ δρ ρ is described, in the sub-horizon limit, by equations of the form δ + 2H δ -4πGρ δ = 0, (5.5) while the full relativistic treatment involves coupled equations for metric and matter perturbations. The solutions of these equations predict the growth of structure, gravitational potentials, and anisotropies across cosmic time.

These perturbative relations constitute the theoretical backbone of large-scale structure formation. They allow cosmology to produce quantitative predictions for galaxy clustering, weak gravitational lensing, redshift-space distortions, the anisotropies of the cosmic microwave background. Crucially, these predictions are not qualitative trends, but precise relations among observables that can be directly confronted with data.

The nomological character of modern cosmology would remain purely formal in the absence of observational access to the quantities appearing in the cosmic dynamical equations. Over the last decades, a remarkably rich and diverse set of independent yet complementary observational probes has emerged, enabling precision tests of cosmic laws across a wide range of redshifts and physical scales.

a. Cosmic Microwave Background (CMB). Measurements of temperature and polarization anisotropies of the cosmic microwave background, from COBE to WMAP and Planck, provide a snapshot of the universe at recombination and encode information about primordial perturbations, geometry, and cosmic composition [3][4][5]. The CMB remains one of the most precise datasets in all of physics.

b. Type Ia Supernovae (SNIa). Observations of type Ia supernovae serve as standardized candles, enabling direct reconstruction of the expansion history of the universe and providing the first robust evidence for late-time cosmic acceleration [7,8].

c. Baryon Acoustic Oscillations (BAO). BAO measurements in galaxy surveys define a standard ruler that constrains the expansion rate and angular diameter distance as functions of redshift, offering a geometrical probe complementary to supernova observations [9,10].

d. Large-Scale Structure and Galaxy Clustering. Large redshift surveys such as 2dF, SDSS, BOSS/eBOSS, and DES measure the statistical distribution of galaxies, constraining the matter density, galaxy bias, and the growth of cosmic structure [6].

e. Cosmic Chronometers. Differential age measurements of passively evolving galaxies provide direct determinations of the Hubble function H(z), independent of integrated distance indicators [24,25].

f. Redshift-Space Distortions and f σ 8 Measurements. Velocity-induced anisotropies in galaxy clustering yield direct access to the growth rate of structure through measurements of f σ 8 , enabling tests of gravity on cosmological scales [26].

g. Weak and Strong Gravitational Lensing. Gravitational lensing probes the integrated matter distribution and spacetime geometry, offering powerful tests of structure formation and gravitational dynamics [11,12].

h. Galaxy Clusters. Cluster number counts, mass functions, and internal properties constrain the amplitude of matter fluctuations and the growth of structure, linking cosmic expansion to nonlinear gravitational collapse [27].

i. Gravitational Waves (Standard Sirens). Compact binary mergers detected through gravitational waves provide absolute luminosity distances, offering an independent probe of cosmic expansion that does not rely on the cosmic distance ladder [13].

j. 21-cm Cosmology. Observations of the hyperfine transition of neutral hydrogen promise to probe the dark ages, cosmic dawn, and reionization, potentially extending precision cosmology to very high redshifts [28].

Taken together, these probes form an interconnected observational network. They do not merely measure isolated quantities, but collectively test the internal consistency of the cosmic dynamical framework across epochs, length scales, and physical regimes. Moreover, this network does not operate as a one-directional verification mechanism. Instead, it establishes a dialectical interplay: precision observations reveal tensions and inconsistencies, such as the Hubble tension, that motivate the development of new theoretical syntheses, which in turn generate novel observational predictions and drive further experimental and methodological advances.

The defining feature of contemporary cosmology is not the mere existence of equations, but their systematic confrontation with an extensive and heterogeneous body of data. Cosmological parameters are now inferred through global likelihood analyses that combine multiple datasets, yielding constraints of unprecedented precision.

Equally important is the internal cross-consistency of cosmological inference. Independent probes constrain overlapping combinations of parameters, enabling non-trivial consistency tests of the underlying theoretical framework. Discrepancies, such as those involving the Hubble constant or the amplitude of matter fluctuations [14], arise precisely because cosmology has reached the level of precision required to expose the limitations of its effective laws.

In this sense, modern cosmology satisfies the operational criteria of a nomological science, including the formulation of general laws, predictive power, and systematic empirical testing [29][30][31][32][33]. It possesses universal equations, predictive structures, and a dense network of observational tests. The observable universe, once accessible primarily through philosophical reflection, has thus become an object of quantitative legislation.

It is this empirical, mathematical, and epistemic transformation that motivates the proposal to regard contemporary cosmology not merely as a logos of the cosmos, but as a genuine nomos of the cosmos.

The developments discussed in the previous sections invite a reassessment of the conceptual status of contemporary cosmology. Historically, cosmology was appropriately understood as a logos of the cosmos: a rational discourse aimed at organizing, interpreting, and philosophically situating the universe as a whole. This designation reflected both the nature of its subject matter and the epistemic tools available at the time. In the absence of global dynamical equations and precision observations, cosmology could not reasonably aspire to the formulation of laws in the strict sense.

This situation has now changed in a fundamental way. As shown in Section V, modern cosmology rests on a welldefined set of dynamical equations governing cosmic evolution, supplemented by a perturbative framework that predicts the formation and growth of structure. These equations are not merely formal constructions. They are systematically confronted with a broad and diverse body of observational data, and their parameters are inferred with increasingly high precision. In operational terms, they function as effective laws of nature.

At a deeper conceptual level, this transition mirrors the historical evolution from astrology to astronomy. Astronomy acquired its status as a “nomy” when celestial phenomena were shown to obey universal, predictive, and empirically testable laws. Once planetary motions could be derived from dynamical principles and subjected to falsification, the study of the heavens ceased to rely on qualitative interpretation and became an exact natural science. In an analogous manner, the observable universe itself has now become an object of quantitative legislation.

From an etymological perspective, this shift can be expressed as a passage from logos to nomos. The proposal to speak of cosmonomy is therefore not a semantic novelty, but a conceptual clarification. It reflects the fact that the cosmos is now investigated through laws that constrain its behavior and evolution, rather than through qualitative narratives alone.

In contemporary practice, the study of the observable universe satisfies the defining criteria of a nomological science. Cosmic evolution is described by equations that are universal in scope, predictive in content, and falsifiable in principle. These equations relate observables across cosmic time and length scales, enabling quantitative reconstruction of the universe’s history and constrained extrapolation toward its future.

Moreover, modern cosmology does not rely on a single observational handle. Instead, it operates through a tightly interconnected network of probes that test the same underlying laws from distinct physical perspectives. The consistency between background expansion, structure growth, gravitational lensing, and primordial anisotropies is not imposed by assumption, but established empirically. Where tensions arise, they serve as diagnostics of either unresolved observational systematics or the limitations of the effective laws themselves.

In this sense, cosmonomy denotes neither a claim of finality nor the discovery of immutable truths about the universe. Rather, it designates a mode of inquiry in which cosmic laws are treated as effective, testable, and revisable descriptions, in close analogy with the laws governing other complex physical systems. The universe remains unique, but it is no longer epistemically exceptional.

Importantly, cosmonomy is deeply connected to fundamental physics. Questions concerning the nature of dark energy, dark matter, gravity, and the “initial” conditions of the universe are now addressed within a framework that directly links theoretical principles to observation. Cosmic laws thus provide a bridge between fundamental physics and empirical reality, situating cosmonomy firmly within the core of modern physics.

The nomological character of cosmology is expected to be further strengthened by forthcoming observational programs. Next-generation surveys and multi-messenger observations will extend precision tests of cosmic laws to new regimes, higher redshifts, and previously inaccessible physical processes. The scope of cosmic legislation will therefore continue to expand, both in depth and in breadth.

At the same time, it is essential to recognize the intrinsic limits of law-based descriptions. Cosmic laws are necessarily effective, reflecting both the finite precision of observations and the theoretical assumptions underlying their formulation. The existence of horizons, the uniqueness of the universe, and the role of initial conditions impose fundamental constraints on what can be known and predicted. For this reason, a clear distinction must be drawn between the observable universe and the totality of reality. In this sense, the study of the cosmos should be regarded as a local science, while rational accounts of regions beyond the cosmological horizon remain within the domain of logos. Acknowledging these limits is a hallmark of a mature nomological perspective, not a refutation of it.

Against this background, the proposal to adopt the term cosmonomy should be understood as a reflection of the evolving identity of the field. It neither denies the historical roots of cosmology nor diminishes the philosophical depth of questions concerning the universe as a whole. Rather, it highlights the fact that cosmology has entered a stage in which its central activity consists in the formulation, testing, and refinement of cosmic laws.

In this work, we have examined the conceptual evolution of cosmology from a historical, epistemological, and methodological perspective, focusing in particular on the criteria that distinguish a qualitative discourse from a law-based scientific discipline. Our analysis shows that, for most of its history, cosmology was necessarily confined to the level of logos: a rational and often profound reflection on the universe as a whole, shaped by the absence of global dynamical laws and by severe observational limitations. This status was neither accidental nor provisional, but a faithful expression of the epistemic conditions under which the cosmos could be studied.

Over the last few decades, this situation has changed in a decisive way. Contemporary cosmology is now characterized by an unprecedented abundance of highquality data, originating from a wide spectrum of independent and complementary observational probes. Measurements of the cosmic microwave background, largescale structure, supernovae, baryon acoustic oscillations, cosmic chronometers, gravitational lensing, galaxy clusters, redshift-space distortions, gravitational waves, and emerging 21-cm observations collectively provide access to the universe across cosmic time and physical scale. Crucially, these datasets are not merely accumulated, but systematically integrated through mature statistical and computational frameworks that enable precision parameter estimation, consistency testing, and meaningful model discrimination.

At the theoretical level, this observational transformation is matched by a well-defined dynamical framework. The evolution of the universe is described by explicit equations at both the background and perturbative levels, allowing for quantitative predictions of expansion history, structure formation, and observable correlations.

These relations function operationally as effective laws: they are universal in scope, predictive in content, and continuously confronted with data. The tensions and discrepancies that arise within this framework should therefore not be interpreted as signs of conceptual fragility, but as indicators of a discipline that has reached the level of precision required to probe the limits of its own laws.

Taken together, these developments motivate a reassessment of the conceptual status of the field. Modern cosmology no longer consists primarily in the qualitative interpretation of the cosmos, but in the formulation, testing, and refinement of quantitative laws governing its evolution. In this sense, the observable universe has ceased to be epistemically exceptional. Despite its uniqueness, it is now investigated through methods that are operationally indistinguishable from those employed in other law-based branches of physics.

On this basis, we have suggested that the term cosmonomy may provide a more accurate descriptor of the present and emerging practice of the field, emphasizing its nomological, predictive, and falsifiable character. This proposal is not intended to erase the historical meaning of cosmology, nor to diminish the philosophical depth of questions concerning the universe as a whole, but it reflects the maturation of the discipline itself, and the fact that cosmology has acquired both the empirical foundation and the theoretical machinery required for genuine cosmic legislation.

Whether or not this terminology is ultimately adopted by the community, the transformation it seeks to articulate is already under way. The observable universe is no longer studied solely as an object of contemplation, but as a system governed by empirically grounded and quantitatively precise laws, persistently confronted with an ever-growing body of data. In this precise and limited sense, cosmology has effectively become cosmonomy.