Science 101: How does a scientific theory become a scientific law? by: William C. Robertson, Ph.D.

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A theory doesn’t become a law. End of story, end of this issue of Science 101. Just kidding—it’s all about the how and why, and that hasn’t been answered. See if this sounds familiar: Scientists begin with a hypothesis, which is sort of a guess of what might happen. When the scientists investigate the hypothesis, they follow a line of reasoning and eventually formulate a theory. Once a theory has been tested thoroughly and is accepted, it becomes a scientific law. Nice progression, and not what happens. To understand how scientists proceed in their investigations, it will help to understand each term individually. What’s a hypothesis, what’s a theory, and what’s a law?

  • Elementary
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Reviews (5)
  • on Thu Mar 22, 2012 3:36 PM

This is a delightful little article that explains words that are tossed around a lot in science class, but unfortunately are not very well understood by many people. This article is great starting point for anyone who is confused about the difference between law, theory, and hypothesis.

Eric Carlson  (Royal City, WA)
Eric Carlson (Royal City, WA)

  • on Tue Oct 25, 2011 10:46 PM

Dr. Robertson has successfully summarized the differences between laws, theories, and hypotheses in this short article. Within this article, we learn that laws describe, theories explain and hypotheses are tentative explanations. This article should be part of every pre-service science curriculum, in my opinion.

Kathryn Kennedy  (Saint Paul, MN)
Kathryn Kennedy (Saint Paul, MN)

  • on Mon Aug 01, 2011 10:56 PM

I also like the way Bill Robertson explains the notion of a hypothesis. One of my biggest gripes is that students are told that a hypothesis is an "educated guess." According to Bill, "A hypothesis is an educated guess coupled with an explanation for why that guess should come true." Even in high school, students are still struggling with that concept. Extending on that idea, "A true test of these hypotheses should include a test of the explanations as well as what they observe." We need to explain the results - confirming or negating our hypothesis. Excellent differentiation of the concepts for all levels.

Jennifer Rahn  (Delafield, WI)
Jennifer Rahn (Delafield, WI)

  • on Thu Jun 30, 2011 11:17 AM

The difference between a hypothesis, theory and law is explained in this article. The process and order of these concepts are also explained and rightfully so because there seems to be a misconception of how one moves from a hypothesis into a law and/or theory. A must read to set the record straight.

Adah  (San Antonio, TX)
Adah (San Antonio, TX)

  • on Wed Apr 27, 2011 6:58 PM

The answer is, it doesn't. Robertson chattily explains the difference between scientific law (a law just states what scientists find, every time they test it); a theory (a theory is a mechanism that explain laws—NOT the same usage as in everyday life); and hypotheses (one of the normal steps to develop understanding of a problem). This article will help boost your science background before you misuse the terms--just in case you might do that. The article ends with a discussion of calling evolution "just a theory."

Allison Cooke
Allison Cooke

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