No, Scientific Hypotheses, Theories, and Laws Aren’t the Same

But science isn’t “truth” or even “a body of knowledge that is backed by substantial evidence.” Rather, science is a systematic process. It’s a methodology that allows us to study and understand the world objectively, relying on testable hypotheses instead of guesswork or opinion. 

And here’s where we begin to run into problems.

Defining the problem 

In science, we frequently use terms like “hypothesis.” This word is one of the cornerstones of science, and so it has a precise definition to those in the scientific community. Unfortunately, the general public often defines this term very differently. 

Most people today know that a person who says “evolution is just a theory” and literally means “evolution is just a guess” isn’t using the term “theory” correctly. However, many other misunderstandings are still unfortunately commonplace. 

For example, many people see scientific hypotheses, theories, and laws as a staircase, where one set of steps leads you reliably to the higher levels. They think, “If the evidence supports a hypothesis, it is upgraded to a theory. If the theory gets even more support, it may be upgraded to a law.” However, hypotheses, theories, and laws differ in scope and never in level of support. 

As the University of California, Berkeley notes, “hypotheses, theories, and laws are rather like apples, oranges, and kumquats: one cannot grow into another, no matter how much fertilizer and water are offered.” It’s absurd how far off we were, right?

Here’s how things actually work: A hypothesis is a testable explanation for a specific observation. A law is a detailed description of how a specific aspect of the world behaves, usually expressed via a mathematical formula (but not always). Theories are deep explanations that cover a broad range of phenomena, incorporating many hypotheses and laws. 

But the former paragraph was a bit of a mouthful, and it leaves a lot left unsaid. So in a (probably, but hopefully not) vain attempt to eliminate any future problems and ensure we are all on the same page, let’s go back to the basics and define what these terms mean, starting with the definition of “science.”

Science

(noun) A method of studying the natural world and establishing facts through observations and experiments.

Science is a system of methods that scientists use to study everything, from the subatomic particles that make up matter to the massive quasars at the very edges of the ever-expanding universe. It’s about making observations, asking good questions, searching for plausible explanations, putting these hypotheses to the test, and rethinking anything (if needed) based on the results of those experiments. 

In short, science is about seeking evidence to gain new knowledge, and it gives us a formula to follow to reliably get the evidence we need to create this knowledge. 

The formula is called the “scientific method,” and here’s how it works: 1) Ask a question. 2) Conduct necessary research to gather information. 3) Form a hypothesis based on research and observations. 4) Create an experiment to test the hypothesis. 5) Evaluate whether the experiment is working (if it’s not, return to four. If it’s working, move on to six). 6) Analyze the results of the experiment and form conclusions. 7) If the results align with your hypothesis, you are done. If the results don’t align with your hypothesis, return to three and repeat.

Hypothesis

(noun) A proposed explanation for a phenomenon that can be tested 

A hypothesis is a tentative explanation for a specific observation or phenomenon. Of course, there are two big dangling qualifiers here. For a hypothesis to be scientifically valid, first, the explanation needs to be testable in an experiment. And second, the experiment needs to be falsifiable. 

In other words, it must be possible to test the hypothesis and (potentially) prove that it’s not true. 

For example, let’s take a look at the following statement. “Male athletes are better at running than female athletes.” The statement isn’t a viable scientific hypothesis because “better” is inherently subjective i.e., the word means different things to different people. To make it a testable claim, we could try to reword the statement to something that’s not opinion-oriented, like “male athletes run two miles 20% faster than female athletes.” To test this hypothesis, we could ask people from both groups to participate in a study that measures their physical capabilities to determine if the statement is true or false — and the degree to which it is consistently true or false. 

But while some untestable statements can be easily reworded to make them testable, there’s often no saving unfalsifiable claims. An example of an unfalsifiable claim is, “a flying spaghetti monster created the universe." This isn’t a scientific hypothesis because there’s no way to prove the claim wrong. 

And, of course, hypotheses are only the beginning. After a scientist comes up with a valid hypothesis, they test it over and over and over again. Once they think that they’ve done enough experiments and collected enough information to show that their hypothesis is true, the torch is handed over to other experts, who test the hypothesis many times in multiple contexts to ensure that the results are reproducible (can be replicated with a high degree of reliability when the experiment is repeated).

Scientific Fact

(noun) a basic statement established by experiments or observations

An everyday person might think of facts as something obvious, like the Sun being yellow. But something seeming obvious isn’t enough for scientists. Scientists think of facts as empirical evidence or an indisputable observation of a phenomenon. 

The difference between the two is a little hard to see but, in essence, scientific facts never rely on any kind of value judgment or assumption 

For a fact to come from empirical evidence, observations are carefully and repeatedly measured to the point that statistical analysis places the result within a small, acceptable margin of error. In fact (pun intended), scientists repeat an experiment over and over again to get a big enough sample size to (hopefully) put their results in the 95 percent (or even 99 percent) confidence interval. That’s a margin of error of just 5 percent (or 1 percent)! 

All that said, most scientists usually don’t say something “is a fact” or “is not a fact.” Instead, scientists tend to discuss how much evidence supports or refutes an idea. 

Oh, and fun fact, the Sun isn’t really yellow. 

Theory

(noun) a well-substantiated explanation of a phenomenon that can incorporate laws, hypotheses, and facts.

Some people think that a theory is an educated guess that hasn’t quite been proven to be true — but that’s absolutely not the case. A theory explains the “why” or “how” of an observation or phenomenon, and this explanation is rooted in scientific evidence.

Kenneth Angielczyk, the MacArthur Curator of Paleomammalogy and Section Head at the Negaunee Integrative Research Center, explains that a theory is “a carefully thought-out explanation for observations of the natural world that has been constructed using the scientific method, and which brings together many facts and hypotheses.” Theories have been substantiated through repeated experiments or testing. They are concise, cohesive, systematic, predictive, and broadly applicable — often integrating and generalizing multiple hypotheses. 

Essentially, theories are the be-all and end-all for scientific inquiries. 

But of course, that doesn’t mean that scientific theories are immutable. They evolve as new evidence comes to light and, like all things in science, can be proven false. However, changing a theory is far from easy because, as previously mentioned, they have been substantiated through repeated experiments.

The strength of a scientific theory depends on how simple it is, the array of phenomena it can be used to explain, and the amount of evidence and observations that support it. 

All that said, there are theories that have been so well-established and have so much evidence backing them up that it’s highly unlikely they will ever be disproven, such as the theory of evolution by natural selection, the theory of plate tectonics, and cell theory — just to name a few. These theories have endured years of experiments and have been confirmed time and time again. 

On the other hand, some theories are new ideas with limited scientific evidence and are slightly more likely to be amended. They may change as scientists learn more and include more facts. 

Some people think that when theories “graduate,” they become laws. That couldn’t be further from the truth. Theories and laws serve completely different purposes. How’s that? Theories explain the “why” and “how” of the phenomenon. Laws don’t.

Law

(noun) the description of an observed phenomenon.

Scientific laws are statements or descriptions of phenomena that are true every time they are tested. In short, laws describe what happens. Notably, they don’t explain why a phenomenon happens, what causes it, etc. That’s what scientific theories are for. Instead, laws typically describe relationships between things and how objects behave in specific circumstances.

For example, the laws of thermodynamics basically describe how the energy in a system changes.

Laws can even be (and often are) equations, like in the case of the ideal gas law, which describes how a gas’ pressure, volume, and temperature are related to one another but doesn’t describe how gasses must behave in general. For many modern scientists, laws are actually the starting point. They take what is known and, from there, ask deeper, more novel questions. 

Scientific laws usually remain consistent. However, from time to time, scientists modify or reject laws if new, unexpected data comes to light. For example, Newton's law of universal gravitation was “tweaked” as new evidence came in and was superseded by Albert Einstein's theory of general relativity, 

Pseudoscience

(noun) a statement that is presented as a valid scientific theory or fact but is incompatible with — and can be disproven using — the scientific method.

Pseudoscience is a belief that is mistakenly regarded as being based on the scientific method. Proponents of pseudoscientific ideas claim their statements are factual, but they’re actually based on assumptions, inaccurate information, ideas that aren’t testable, and so on. 

The difference between science and pseudoscience is a lot like answering the question: What’s the difference between astronomy and astrology? Astronomy is the scientific study of celestial bodies and phenomena. Astrology is divination i.e, predictions aren’t based on evidence, aren’t testable, aren’t falsifiable, and aren’t reproducible.

Ultimately, the primary problem with pseudoscience isn’t simply that it’s wrong. It’s that it actively claims to be real science. As a result, it has the potential to be really dangerous for society. We saw how far things could escalate during the Covid-19 pandemic, when cures for the virus included cow urine, bleach, and cocaine. Unfortunately, many of these Covid-19 therapies were then backed by various governments. Their messages were, in turn, amplified by social media algorithms. And the consequences to human health and life were terribly real.

So, what’s the best way to fight misinformation? Good science is truly the only valuable tool we have in this fight. Use it wisely.