Difference Between Law and Theory (With Table)

In scientific methods, theorizing and formulating laws are two important steps. Law and Theory are two words which are interrelated and used often when it comes to Science.   

People often think they can used alternatively,  however , they have very different meanings and understanding the differences is necessary to better understand Science. 

Law vs Theory 

The difference between Law and Theory is that a law is based on facts, it is a detailed explanation of how some part of the natural world works, and is generally based on mathematics and on the other hand a theory is a hypothesis that seeks to explain something which may be based on a coincidence or a fact that hasn’t been completely explained. 

Laws are universally recognised and are the foundations of science. They must never make a mistake. If a law is indeed proven to be inaccurate, all science based on it is also incorrect.

When a law is written, it contains no explanations, it is a fact based on observations. Science believes all scientific laws and theories to be valid. When new evidence arises, however, theories may be disproven. 

Theory is a proposed explanation that is based on rigorous studies and interpretation. Theories can be used to generate hypothesis and they allow for error and, as a result, allow for change as new discoveries either strengthen or radically change them. 

Comparison Table Between Law and Theory 

Parameters of comparison Law  Theory 
Definition A law is a universally accepted fact or equation that can be used to make accurate predictions. A theory is a comprehensive explanation based on well-documented and data from experiments that observe natural processes. 
Requirement  A law must be factual and should be unchanging. A theory must be substantiated, explanatory, predictive, and testable in order to be valid. 
Changes A law cannot be changed with time. A law is always constant. A theory can be changed or replaced after extensive research and by time. 
Example Mendel’s Law of Independent Assortment. The theory of the Big Bang or Darwin’s theory of Evolution. 

What is Law? 

A law is a verbal or mathematical statement that summarises a large number of experimental findings in science. It explains or forecasts those aspects of the natural world that never change under the same circumstances.  Law is any scientific theory that has been proven valid repeatedly and is thus accepted without doubt by the majority of people. 

The law of gravity is a prime example of this. It has been noted that an apple falls to the Earth’s surface. It’s a truth that can’t be denied. There are no exceptions to this rule. No one has ever seen a phenomenon in reverse or in the opposite direction. As a consequence, it is considered a law. 

It is something that has been proven to be true over time but has no real explanation for why it occurs. Hooke’s law, for example, does not explain why a spring works, Newton’s law of gravity does not explain why gravity exists.To put it another way, a law explains how something works but not why. 

Laws help you predict what will happen in specific situations. Newton’s third rule, for example, states that the harder a softball is struck with a bat, the faster and further the ball will fly away from the bat. 

What is Theory? 

In common usage, the term “theory” implies mere speculation, but in science, a theory is not considered a theory until it has been validated by several independent experiments. A theory is a well-supported interpretation of any aspect of the natural world based on evidence, assumptions, and laws. 

A theory is a formalised interpretation of observational evidence in the form of a law. In simple terms, a theory is the logic that underpins a law. A theory, as described by the scientific community, describes how nature acts under some circumstances. Theories appear to be as large as the empirical evidence that supports them allows. 

The beginning of a theory is a hypothesis, that is a proposed explanation for a natural phenomenon. Researchers develop scientific experiments to test their theories under natural conditions in order to transform a hypothesis into an established theory. Scientists collect enough evidence to prove their hypothesis, making it a theory with predictive ability, by following the scientific method and paying close attention to detail. 

Theories serve as the basis for advancing scientific understanding and putting the knowledge to practical use. Theories are used by scientists to create new inventions or find a cure for a disease. 

Theories can evolve, but it’s a long process. Many findings or pieces of evidence that the theory cannot explain are required for a theory to alter. 

Main Differences Between Law and Theory 

  1. Theories are scientifically supported explanations of observations that make valid predictions and have been scientifically tested in a variety of ways, while laws are widely accepted facts or equations capable of making true predictions. 
  2. Theories describe how nature functions, while laws describe what happens when those conditions are met. 
  3. Laws are a compilation of a vast number of facts, while theory is complicated and descriptive. 
  4. A theory may be substituted by a better theory; however, a law cannot be replaced. 
  5. According to the amount of evidence available, a theory may be strong or weak whereas law is a truth that is uniformly observed. 


A law is a statement that explains what has always been observed to happen under specific specified circumstances in a precise but short manner, and is often expressed as a single mathematical equation. 

Laws are distinct from theories in that they appear to describe a more limited range of circumstances. Theories tend to be more detailed, concentrating on the how and why of natural phenomena.  

A theory and a law are both generally acknowledged as valid by the scientific community as a whole. Both are used to make predictions about what will happen next and are working in the advancement of technology. 


  1. https://arch.alcaweb.org/archfs/v6/26044/o/3999de1f48b358e1dc0aafa9023dae7c.pdf
  2. https://eric.ed.gov/?id=EJ1057150
  3. https://search.proquest.com/openview/cc7b21eb88f453627695c0918a23e346/1?pq-origsite=gscholar&cbl=40590