Do Theories Ever Become Laws?

STEMgineer’s Guide to Problem Solving Workbooks

What differentiates a scientific theory from a law? Most people believe that a scientific theory becomes a law if there’s enough proof to back it up, but this is actually a misconception. Theories and laws serve different purposes in science. Many people confuse the two because they both describe scientific phenomena. The biggest difference is that laws explain what happens, and theories explain why or how something happens.

What Is a Scientific Law?

A scientific law describes what happens in nature. They are based on repeated observations and measurable patterns. Most laws are written like mathematical equations that explain the relationship between variables. For example, the law of universal gravitation states that all objects with mass are attracted to each other, and the attraction is stronger when the object has more mass. This means that when you drop an apple, it will fall toward the ground because the Earth has significantly more mass than the apple. Similarly, the law of conservation of mass states that mass can change form in a chemical reaction, but it doesn’t disappear. For example, when you burn wood, the mass of the wood doesn’t disappear; it becomes ash and smoke.

What Is a Scientific Theory?

A scientific theory explains why or how something happens. Theories are also built from observation and testing. They provide a framework for explaining why a law happens. For example, the law of universal gravitation is explained by the theory of relativity. When you drop an object, you can see it fall, but you can’t observe why it falls. The theory of relativity explains that bends in the fabric of spacetime cause gravity. For the law of conservation of mass, the reason why the mass stays the same is explained by atomic theory. The number of atoms stays the same in a chemical reaction; they’re just rearranged into different forms. This means the mass stays the same. Theories don’t have to be connected to a scientific law. For example, germ theory isn’t connected to a law, but it explains how diseases can spread through microorganisms. Most theories are supported by extensive evidence, but no amount of evidence can change a theory into a law.

Why Understanding This Difference Matters

Theories and laws answer different questions. Laws describe while theories explain. A theory cannot “graduate” into a law. Knowing this difference helps students understand scientific discussions. Theories aren’t less trustworthy or true because they aren’t laws. Many scientific theories, like germ theory and relativity, have been proven by repeated scientific experiments. Other theories are continually tested and refined to further our understanding of the world.

Science Is Always Evolving

Science constantly improves as new evidence emerges. Our understanding of the world is always getting closer to the truth, but we may never have absolute certainty. Like a curve that approaches a line but never reaches it, our scientific knowledge is close to reality, but discoveries and innovations are always changing our understanding. Students should understand that science is evolving, but that doesn’t mean that our current theories are completely incorrect. Many discoveries support or refine existing theories. 

Laws Describe, Theories Explain

Understanding the difference between a scientific theory and a law is crucial to improve students’ critical thinking skills. They play different roles, but that doesn’t mean that one is better than the other. Laws describe what happens, and theories explain why it happens. Both are essential to understanding the world, and knowing the difference helps students think critically about scientific research and discussions.

Read more deep dives from STEM to Stern at the links below.

STEM Education Works is dedicated to providing cost-effective and user-friendly access to top-notch STEM curricula and technologies, driven by our mission to transform students’ lives. Learn more about what we do through our socials, Facebook,  Twitter,  Youtube,  LinkedIn,  Instagram, and TikTok.