A law is a universal principle that describes the fundamental nature of something, the universal properties and the relationships between things, or a description that purports to explain these principles and relationships.

Laws of nature

For example, physical laws such as the

law of gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the str ...

scientific law Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term ''law'' has diverse usage in many cases (approximate, accurate, broad, or narrow ...

s attempt to describe the fundamental nature of the universe itself. Laws of

mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...

and

logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from prem ...

describe the nature of rational thought and inference (

Kant Immanuel Kant (, , ; 22 April 1724 – 12 February 1804) was a German philosopher and one of the central Enlightenment thinkers. Born in Königsberg, Kant's comprehensive and systematic works in epistemology, metaphysics, ethics, and aest ...

transcendental idealism Transcendental idealism is a philosophical system founded by German philosopher Immanuel Kant in the 18th century. Kant's epistemological program is found throughout his '' Critique of Pure Reason'' (1781). By ''transcendental'' (a term that dese ...

, and differently G. Spencer-Brown's work '' Laws of Form'', was precisely a determination of the ''

a priori ("from the earlier") and ("from the later") are Latin phrases used in philosophy to distinguish types of knowledge, justification, or argument by their reliance on empirical evidence or experience. knowledge is independent from current ex ...

'' laws governing human thought before any interaction whatsoever with experience). Within most fields of study, and in science in particular, the elevation of some principle of that field to the status of law usually takes place after a very long time during which the principle is used and tested and verified; though in some fields of study such laws are simply postulated as a foundation and assumed. Mathematical laws are somewhere in between: they are often arbitrary and unproven in themselves, but they are sometimes judged by how useful they are in making predictions about the real world. However, they ultimately rely on arbitrary

axioms An axiom, postulate, or assumption is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments. The word comes from the Ancient Greek word (), meaning 'that which is thought worthy or f ...

Laws in social sciences

Laws of

economics Economics () is the social science that studies the production, distribution, and consumption of goods and services. Economics focuses on the behaviour and interactions of economic agents and how economies work. Microeconomics anal ...

are an attempt in

modelization A mathematical model is a description of a system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used in the natural sciences (such as physics, ...

of economic behavior.

Marxism Marxism is a Left-wing politics, left-wing to Far-left politics, far-left method of socioeconomic analysis that uses a Materialism, materialist interpretation of historical development, better known as historical materialism, to understand S ...

criticized the

belief A belief is an attitude that something is the case, or that some proposition is true. In epistemology, philosophers use the term "belief" to refer to attitudes about the world which can be either true or false. To believe something is to tak ...

in eternal laws of economics, which it considered a product of the

dominant ideology In Marxist philosophy, the term dominant ideology denotes the attitudes, beliefs, values, and morals shared by the majority of the people in a given society. As a mechanism of social control, the dominant ideology frames how the majority of the ...

. It claimed that in fact, those so-called laws of economics were only the historical laws of

capitalism Capitalism is an economic system based on the private ownership of the means of production and their operation for profit. Central characteristics of capitalism include capital accumulation, competitive markets, price system, private ...

, that is of a particular historical social formation. With the advent, in the 20th century, of the application of mathematical, statistical, and experimental techniques to economics, economic theory matured into a corpus of knowledge rooted in the scientific method rather than in philosophical argument.

Miscellaneous

Finally, the term is sometimes applied to less rigorous ideas that may be interesting observations or relationships, practical or ethical guidelines (also called

rules of thumb In English, the phrase ''rule of thumb'' refers to an approximate method for doing something, based on practical experience rather than theory. This usage of the phrase can be traced back to the 17th century and has been associated with various t ...

), and even humorous parodies of such laws. Examples of scientific laws include

Boyle's law Boyle's law, also referred to as the Boyle–Mariotte law, or Mariotte's law (especially in France), is an experimental gas law that describes the relationship between pressure and volume of a confined gas. Boyle's law has been stated as: The ...

of gases,

conservation law In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves over time. Exact conservation laws include conservation of energy, conservation of linear momentum, c ...

Ohm's law Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equa ...

, and others. Laws of other fields of study include

Occam's razor Occam's razor, Ockham's razor, or Ocham's razor ( la, novacula Occami), also known as the principle of parsimony or the law of parsimony ( la, lex parsimoniae), is the problem-solving principle that "entities should not be multiplied beyond neces ...

as a principle of

philosophy Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, knowledge, values, mind, and language. Such questions are often posed as problems to be studied or resolved. ...

and

Say's law In classical economics, Say's law, or the law of markets, is the claim that the production of a product creates demand for another product by providing something of value which can be exchanged for that other product. So, production is the source ...

. Examples of observed phenomena often described as laws include the Titius-Bode law of planetary positions, Zipf's law of linguistics,

Thomas Malthus Thomas Robert Malthus (; 13/14 February 1766 – 29 December 1834) was an English cleric, scholar and influential economist in the fields of political economy and demography. In his 1798 book ''An Essay on the Principle of Population'', Mal ...

's Principle of Population or Malthusian Growth Model,

Moore's law Moore's law is the observation that the number of transistors in a dense integrated circuit (IC) doubles about every two years. Moore's law is an observation and projection of a historical trend. Rather than a law of physics, it is an empi ...

of technological growth. Other laws are pragmatic and observational, such as the law of unintended consequences. Some humorous parodies of such laws include

adage An adage (; Latin: adagium) is a memorable and usually philosophical aphorism that communicates an important truth derived from experience, custom, or both, and that many people consider true and credible because of its longeval tradition, i ...

s such as Murphy's law and its many variants, and Godwin's Law of

Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, p ...

conversations.

Laws of nature

Laws in social sciences

Miscellaneous

See also