Hypothesis, Theory, Law, Fact. What's the Difference?

   Question: what is a scientific theory? What differentiates a scientific theory and its ilk, hypotheses, laws, fact, et cetera? Is scientific fact immutable? Unfortunately, many people lack an understanding on how scientific definitions are defined and how the scientific method is applied in the fields of science. In a sense, it is understandable as fields like science, social science, and the rest often have definitions and uses that vastly differ from the common language. For example, 'heat' in regards to animal behavior in the field of anthropology can refer to estrus and how/when a species enters a period of sexual receptivity. However, as humans, we do not use the word often or confuse heat/estrus with its more typical definition because humans—human females—are in the category of animals that have a hidden estrus. A scientific control, a noun, differs from the average control that often used as a verb; the scientific control is method by which a variable or variables is usually held constant so that the impact of a certain factor may be accounted for in a test. [1] Within the English language, especially in the American dialect, a theory is often synonymous with a guess or hypothesis. So, naturally, when one who knows not better hears of a scientific theory or, even, hypothesis, one may simply regard them as simply a guess. Vernacular aside, in science, a scientific theory is defined as something like

1) The grandest synthesis of a large and important body of information about some related group of natural phenomena (Moore, 1984)  

2) A body of knowledge and explanatory concepts that seek to increase our understanding ("explain") a major phenomenon of nature (Moore, 1984). 

3) A scientifically accepted general principle supported by a substantial body of evidence offered to provide an explanation of observed facts and as a basis for future discussion or investigation (Lincoln et al., 1990). 

4) 1. The abstract principles of a science as distinguished from basic or applied science. 2. A reasonable explanation or assumption advanced to explain a natural phenomenon but lacking confirming proof (Steen, 1971). [NB: I don't like this one but I include it to show you that even in "Science dictionaries" there is variation in definitions which leads to confusion]. 

5) A scheme or system of ideas or statements held as an explanation or account of a group of facts or phenomena; a hypothesis that has been confirmed or established by observation or experiment, and is propounded or accepted as accounting for the known facts; a statement of what are held to be the general laws, principles or causes of something known or observed. (Oxford English Dictionary, 1961; [emphasis added]).

 6) An explanation for an observation or series of observations that is substantiated by a considerable body of evidence (Krimsley, 1995). [2]

With the scientific theory being defined, a scientific hypothesis is quite similar. Britannic defines the scientific hypothesis as an idea that proposes a tentative explanation about a phenomenon or a narrow set of phenomena observed in the natural world. The two primary features of a scientific hypothesis are falsifiability and testability, which are reflected in an “If...then” statement summarizing the idea and in the ability to be supported or refuted through observation and experimentation. [3] So, essentially, a hypothesis can be hold true and, even then, can still remain a hypothesis due to several reasons. One of those reasons being that a hypothesis can be tested, verified, and or falsified. As my biology professor instructed me, a theory and hypothesis can differ in four or more ways.

I. Theories are supported by multiple lines of evidencesII. Theories tends to explain more phenomena and have more explanations.III. Theories may not be testable.IV. Theories tend to have more supporting evidences. 

In short, hypotheses may explain phenomena, in a narrow sense, while also being testable and or falsifiable. [4] Theories may explain phenomena in a broad sense while likely embodying related hypotheses and evidences and having few exceptions to what it predicts. [5] [6]

   Scientific laws are rarely, if ever, contested by those not in the science fields but I feel inclined as to define and explain what a scientific law is and its relevance to hypotheses and theories. Laws are often defined as a scientific law is a description of a natural phenomenon or principle that invariably holds true under specific conditions and will occur under certain circumstance. [7] [8] In a sense, laws account for their own exceptions with explanations like in the case of Mendel's laws of Independent assortment and or Law of Segregation. This being so and with the addition of scientific fact being mutable and subject to change, I like to think of science as being pragmatic—open to change and improvement. Berkeley explains what scientific facts mean much better than I may describe it be.

Facts are statements that we know to be true through direct observation. In everyday usage, facts are a highly valued form of knowledge because we can be so confident in them. Scientific thinking, however, recognizes that, though facts are important, we can only be completely confident about relatively simple statements. For example, it may be a fact that there are three trees in your backyard. However, our knowledge of how all trees are related to one another is not a fact; it is a complex body of knowledge based on many different lines of evidence and reasoning that may change as new evidence is discovered and as old evidence is interpreted in new ways. Though our knowledge of tree relationships is not a fact, it is broadly applicable, useful in many situations, and synthesizes many individual facts into a broader framework. Science values facts but recognizes that many forms of knowledge are more powerful than simple facts.  [9]

Scientific fact holds a much different meaning than in the vernacular to some; one may think or regard fact, scientific or not, is absolute and immutable but this is rarely the case. Lastly, one may easily think that a scientific hypothesis may evolve into a theory or law—or theory to law/fact. However, this is not so; hypotheses tend to remain as hypotheses, laws as laws, and facts as facts. In some cases, a theory may be both theory and fact like in the case of evolution. [10] [11] [12] 

TL;DR: hypotheses may hold true and not be regarded as a theory; a theory may hold true and not be regarded as a law or fact; a law or fact may hold true but may be subject to change so to accord with current evidences. 

Link to image: http://www.slideshare.net/michael_gezae/hypothesis-7600477




1: http://undsci.berkeley.edu/glossary/glossary.php
2: http://science.kennesaw.edu/~rmatson/3380theory.html
3: http://www.britannica.com/topic/scientific-hypothesis
4: http://undsci.berkeley.edu/article/howscienceworks_19
5: http://undsci.berkeley.edu/article/howscienceworks_19
6: http://sci.waikato.ac.nz/evolution/Theories.shtml
7: http://sci.waikato.ac.nz/evolution/Theories.shtml
8: http://science.kennesaw.edu/~rmatson/3380theory.html
9: http://undsci.berkeley.edu/teaching/misconceptions.php#a1
10: http://www.evolution.mbdojo.com/theory.html
11: http://www.stephenjaygould.org/library/gould_fact-and-theory.html
12: https://en.wikipedia.org/wiki/Evolution_as_fact_and_theory