The principles and theories of science have been established through repeated experimentation and observation and have been refereed through peer review before general acceptance by the scientific community. Acceptance does not imply rigidity or constraint, or denote dogma. Instead, as new data become available, previous scientific explanations are revised and improved, or rejected and replaced. Science is a way of making sense of the world, with internally-consistent methods and principles that are well described. There is a progression from a hypothesis to a theory using testable, scientific laws. Only a few scientific facts are natural laws and many hypotheses are tested to generate a theory. Find out how scientific hypotheses, theories and laws describe the natural world. Show
A hypothesis is an idea or proposition that can be tested by observations or experiments, about the natural world. In order to be considered scientific, hypotheses are subject to scientific evaluation and must be falsifiable, which means that they are worded in such a way that they can be proven to be incorrect. Example: When Gregor Mendel in 1865 studied the pattern of single trait inheritance of garden peas he formed a hypothesis on the manner of how these traits were inherited. The hypothesis he formed based on his observations included the following:
To scientists, a theory is a coherent explanation for a large number of facts and observations about the natural world. A theory is:
In popular use, a theory is often assumed to imply mere speculation, but in science, something is not called a theory until it has been confirmed over many independent experiments. Theories are more certain than hypotheses, but less certain than laws. The procedures and processes for testing a theory are well-defined within each scientific discipline. Example: Between 1856 and 1863 Mendel cultivated and tested some 28,000 pea plants which brought forth two theories of how character traits are inherited. Ironically, when Mendel's paper was published on 1866, it had little impact. It wasn't until the early 20th century that the enormity of his ideas was realized. A scientific law is a description of a natural phenomenon or principle that invariably holds true under specific conditions and will occur under certain circumstances. Example: In the early 20th century, after repeated tests and rejection of all competing theories Mendel's Laws of Heredity were accepted by the general scientific community.
Lots of historical and scientific information about Gregor Mendel and his work can be found at the Mendel Museum. Example 2: In the late 17th Century, Nicholas Steno established some natural laws relating to geology. \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)
Learning Objectives
Although many have taken science classes throughout the course of their studies, people often have incorrect or misleading ideas about some of the most important and basic principles in science. Most students have heard of hypotheses, theories, and laws, but what do these terms really mean? Prior to reading this section, consider what you have learned about these terms before. What do these terms mean to you? What do you read that contradicts or supports what you thought? What is a Fact?A fact is a basic statement established by experiment or observation. All facts are true under the specific conditions of the observation. What is a Hypothesis?One of the most common terms used in science classes is a "hypothesis". The word can have many different definitions, depending on the context in which it is being used:
What is a Theory?The United States National Academy of Sciences describes what a theory is as follows: "Some scientific explanations are so well established that no new evidence is likely to alter them. The explanation becomes a scientific theory. In everyday language a theory means a hunch or speculation. Not so in science. In science, the word theory refers to a comprehensive explanation of an important feature of nature supported by facts gathered over time. Theories also allow scientists to make predictions about as yet unobserved phenomena." "A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experimentation. Such fact-supported theories are not "guesses" but reliable accounts of the real world. The theory of biological evolution is more than "just a theory." It is as factual an explanation of the universe as the atomic theory of matter (stating that everything is made of atoms) or the germ theory of disease (which states that many diseases are caused by germs). Our understanding of gravity is still a work in progress. But the phenomenon of gravity, like evolution, is an accepted fact. Note some key features of theories that are important to understand from this description:
What is a Law?Scientific laws are similar to scientific theories in that they are principles that can be used to predict the behavior of the natural world. Both scientific laws and scientific theories are typically well-supported by observations and/or experimental evidence. Usually scientific laws refer to rules for how nature will behave under certain conditions, frequently written as an equation. Scientific theories are more overarching explanations of how nature works and why it exhibits certain characteristics. As a comparison, theories explain why we observe what we do and laws describe what happens. For example, around the year 1800, Jacques Charles and other scientists were working with gases to, among other reasons, improve the design of the hot air balloon. These scientists found, after many, many tests, that certain patterns existed in the observations on gas behavior. If the temperature of the gas is increased, the volume of the gas increased. This is known as a natural law. A law is a relationship that exists between variables in a group of data. Laws describe the patterns we see in large amounts of data, but do not describe why the patterns exist. What is a Belief?A belief is a statement that is not scientifically provable. Beliefs may or may not be incorrect; they just are outside the realm of science to explore. Laws vs. TheoriesA common misconception is that scientific theories are rudimentary ideas that will eventually graduate into scientific laws when enough data and evidence has accumulated. A theory does not change into a scientific law with the accumulation of new or better evidence. Remember, theories are explanations and laws are patterns we see in large amounts of data, frequently written as an equation. A theory will always remain a theory; a law will always remain a law. Video \(\PageIndex{1}\): What’s the difference between a scientific law and theory?Summary
Contributions & Attributions
1.6: Hypothesis, Theories, and Laws is shared under a CK-12 license and was authored, remixed, and/or curated by Marisa Alviar-Agnew & Henry Agnew. What is needed for a theory to be scientific?Scientific theories are testable. New evidence should be compatible with a theory. If it isn't, the theory is refined or rejected. The longer the central elements of a theory hold—the more observations it predicts, the more tests it passes, the more facts it explains—the stronger the theory.
What does a scientific theory need to be valid?Answer and Explanation: A theory is supported by scientific evidence and verified research. A theory predicts certain results, which are verified by experiments or observations. If experiments or observations do not verify the predictions made by a theory, then the theory is not said to be valid.
What makes a good scientific theory?Characteristics of a good theory
Theories are concise, coherent, systematic, predictive, and broadly applicable, often integrating and generalizing many hypotheses."
What is the most important feature that a theory must have to be scientific?The most important feature of a scientific theory is that is supported by data from research studies.
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