Scientific Principle — Definition & Examples

Principle vs. Law

A law describes an event, but it does not explain why the event happens. Laws describe relationships, specific situations, and conditions. This is different from a principle, which tells us why and how things happen.

Principles

Principles are ideas based on scientific rules and laws that are generally accepted by scientists. They are fundamental truths that are the foundation for other studies. Principles are qualitative.

They aren't really rules that can be written down with mathematical symbols. They are more like guiding ideas that scientists use to make predictions and develop new laws.

Principle of Relativity: Physical laws take the same form in all systems of reference. (Albert Einstein)

Principle of Special Relativity: The speed of light is the same for all observers. (Albert Einstein)

Pauli Exclusion Principle: No two particles with the same quantum numbers can be at the same position in space and time. (Wolfgang Pauli)

Laws

Newton's law of gravitational attraction describes how objects are influenced by gravity. If you drop an apple, it will fall. If you throw an apple in the air, it will follow a specific path while falling down. Newton's laws don't tell us why the apple falls or what causes it to fall, just that it does fall.

Similarly, the law of conservation of mass says that mass can't be created or destroyed. It doesn't say why this is true, neither does it say how it is true. It just says what happens—mass is always conserved.

Scientific laws can be written as mathematical equations, so they are called quantitative. However, there aren't very many laws in biology. They are more common in physics and chemistry. I listed a few of these equations below.

Newton's 2nd Law: F = ma

Hooke's Law: F = kx

Gauss' Law: ∇E=ρ

Sometimes, people use the terms "principle" and "law" interchangeably. This is because both result in reliable predictions of natural phenomena.

Principal Principle

What Is a Scientific Principle?

A principle is defined as a culmination of the scientific laws and theories that have been previously studied.

The terms principle and law are sometimes used interchangeably because both result in true predictions of natural phenomena over a large period of time.