Theories and laws in Science

September 26, 2016


Slide 47


The process of works at multiple levels — from the small scale (e.g., a comparison of the genes of three closely related North American butterfly species) to the large scale (e.g., a half-century-long series of investigations of the idea that geographic isolation of a population can trigger speciation). The process of science works in much the same way whether embodied by an individual scientist tackling a specific problem, question, or over the course of a few months or years, or by a community of scientists coming to agree on broad ideas over the course of decades and hundreds of individual and studies. Similarly, scientific explanations come at different levels:

Hypotheses
Hypotheses are proposed explanations for a fairly narrow set of phenomena. These reasoned explanations are not guesses — of the wild or educated variety. When scientists formulate new hypotheses, they are usually based on prior experience, scientific background knowledge, preliminary, and logic. For example, scientists observed that alpine butterflies exhibit characteristics intermediate between two species that live at lower elevations. Based on these observations and their understanding of speciation, the scientists hypothesized that this species of alpine butterfly evolved as the result of hybridization between the two other species living at lower elevations.

Theories on the other hand, are broad explanations for a wide range of phenomena. They are concise (i.e., generally don't have a long list of exceptions and special rules), coherent, systematic, predictive, and broadly applicable. In fact, theories often integrate and generalize many hypotheses. For example, the theory of natural selection broadly applies to all populations with some form of inheritance, variation, and differential reproductive success — whether that population is composed of alpine butterflies, fruit flies on a tropical island, a new form of life discovered on Mars, or even bits in a computer's memory. This theory helps us understand a wide range of observations (from the rise of antibiotic-resistant bacteria to the physical match between pollinators and their preferred flowers), makes predictions in new situations (e.g., that treating AIDS patients with a cocktail of medications should slow the evolution of the virus), and has proven itself time and time again in thousands of experiments and observational studies. "JUST" A THEORY?

Occasionally, scientific ideas (such as biological evolution) are written off with the putdown "it's just a theory." This slur is misleading and conflates two separate meanings of the word theory: in common usage, the word theory means just a hunch, but in science, a theory is a powerful explanation for a broad set of observations. To be accepted by the scientific community, a theory (in the scientific sense of the word) must be strongly supported by many different . So biological evolution is a theory (it is a well-supported, widely accepted, and powerful explanation for the diversity of life on Earth), but it is not "just" a theory.

Words with both technical and everyday meanings often cause confusion. Even scientists sometimes use the word theory when they really mean hypothesis or even just a hunch. Many technical fields have similar vocabulary problems — for example, both the terms work in physics and ego in psychology have specific meanings in their technical fields that differ from their common uses. However, context and a little background knowledge are usually sufficient to figure out which meaning is intended.

Over-arching theories
Some theories, which we'll call, are particularly important and reflect broad understandings of a particular part of the . Evolutionary theory, atomic theory, gravity, quantum theory, and plate tectonics are examples of this sort of over-arching theory. These theories have been broadly supported by multiple lines of evidence and help frame our understanding of the world around us.

Source: undsci.berkeley.edu
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Is evolution theory or law in science? | Yahoo Answers

Evolution is a theory. Gravity is both a theory and law -- it is a law to the extent that we have definitively determined the measure of force exerted upon objects by the mass of the Earth, but it is a theory because we don't actually know why mass has a gravitational effect on other bodies of mass. In any event, theories do not graduate to become laws. Theories and laws describe different things in a scientific context.
Bear in mind, though, that the term "theory" has a different meaning when talking about a scientific theory as opposed to a layman's theory. Scientific theories are ex…

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