Lesson 2-04 Theory vs Hyphothesis

Opened 10/05 assignments due 10/07 

LESSON 2.04 – Theory vs. Hypothesis

Standard:  IE1.a, f, k




In this lesson you will learn the difference between a theory and a hypothesis.



1.    1.  Read the following:


Scientific Hypotheses


A scientific hypothesis is an "educated guess". 


A hypothesis must meet 2 criteria: it must be 1) testable and 2) falsifiable.  For a more complete explanation of the term "hypothesis", go to http://www.batesville.k12.in.us/physics/PhyNet/AboutScience/Hypotheses.html



Scientific Theories



Scientific theories are hypotheses which have stood up to repeated attempts at falsification and are thus supported by a great deal of data and evidence. Some well known biological theories include the theory of evolution by natural selection, the cell theory (the idea that all organisms are made of cells), and the germ theory of disease (the idea that certain microbes cause certain diseases). The scientific community holds that a greater amount of evidence supports these ideas than contradicts them, and so they are referred to as theories.



Scientific theories are the equivalent of what in everyday speech we would refer to as facts. In principle, scientific theories are always subject to corrections or inclusion in another, wider theory. As a general rule for use of the term, theories tend to deal with broader sets of phenomena than do hypotheses, which usually deal with much more specific sets of phenomena or specific applications of a theory.



A scientific theory must meet the following requirements:



·         it must be consistent with pre-existing theory in that the pre-existing theory has been experimentally verified, though it may often show a pre-existing theory to be wrong in an exact sense

·         It must be supported by many strands of evidence rather than a single foundation, ensuring that it is probably a good approximation, if not totally correct.

Also, a theory is generally only taken seriously if it:

·         Allows for changes to be made as new data are discovered, rather than claiming absolute certainty.

·         Is the most straight forward explanation, and makes the fewest assumptions about a phenomenon (commonly called “passing the Occam's razor test”).



This is true of such established theories as special relativity, general relativity, quantum mechanics, plate tectonics, and evolution. Theories considered scientific meet at least most, but ideally all, of these extra criteria.



In summary, to meet the status of a scientific theory, the theory must be testable.

Examples of scientific theories in different areas of science include:



·         Astronomy: Big Bang Theory

·         Biology: Cell Theory; Theory of Evolution; Germ Theory of Disease

·         Chemistry: Atomic Theory; Kinetic Theory of Gases

·         Physics: General Relativity; Special Relativity; Theory of Relativity; Quantum Field Theory

·         Earth Science: Giant Impact Theory; Plate Tectonics



Currently Unverifiable Theories



The term theory is sometimes stretched to refer to theoretical speculation which is currently unverifiable. Examples are string theory and various theories of everything. String theory is a model of physics, which predicts the existence of many more dimensions in the universe than the four dimensions that current science understands (length, width, height, and space-time). A theory of everything is a hypothetical theory in physics that fully explains and links together all known physical phenomena.



For a scientific theory to be valid it must be verified experimentally. Many parts of the string theory are currently untestable due to the large amount of energy that would be needed to carry out the necessary experiments as well as the high cost of conducting them. Therefore string theory may not be tested in the foreseeable future. Some scientists have asked if it even deserves to be called a scientific theory because it is not falsifiable.




  1. Create a Word document and save it as: “2.04-yourlastname.doc”
  2. In 100 words or more explain the difference between theory and hypothesis.   Give an example as part of your explanation.
  3. Turn-in your file into the drop-box.