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| Introduction to scientific method | |
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See also: History of scientific method and Timeline of the history of scientific method
Ibn al-Haytham (Alhazen), 965–1039 Iraq. The Arab scholar who lived during the Islamic golden age is considered the father of modern scientific methodology
"Modern science owes its present flourishing state to a new scientific method which was fashioned by Galileo Galilei (1564-1642)" —Morris Kline[5]
Johannes Kepler (1571–1630). "Kepler shows his keen logical sense in detailing the whole process by which he finally arrived at the true orbit. This is the greatest piece of Retroductive reasoning ever performed." —C. S. Peirce, circa 1896, on Kepler's reasoning through explanatory hypotheses[6]
Ibn al-Haytham (Alhazen, 965–1039), is considered the father of the scientific method. According to Shmuel Sambursky, his emphasis has been on seeking truth:
Truth is sought for its own sake. And those who are engaged upon the quest for anything for its own sake are not interested in other things. Finding the truth is difficult, and the road to it is rough.[7]
"Light travels through transparent bodies in straight lines only" — Alhazen in Book of Optics (1021 Arabic: Kitāb al-Manāẓir) as shown in a Basle 1572 Latin translation, Friedrich Risner, ed., Opticae Thesaurus Alhazeni Arabis,[8] frontispiece showing optical phenomena: transmission of light through the atmosphere, reflection of light rays from parabolic mirrors during the defense of Syracuse by Archimedes against ships of the Roman Republic, refraction of light rays by water, and the production of colors in a rainbow.
How does light travel through transparent bodies? Light travels through transparent bodies in straight lines only.... We have explained this exhaustively in our Book of Optics. But let us now mention something to prove this convincingly: the fact that light travels in straight lines is clearly observed in the lights which enter into dark rooms through holes.... [T]he entering light will be clearly observable in the dust which fills the air.[9]
The conjecture that "light travels through transparent bodies in straight lines only" was corroborated by Alhazen only after years of effort. His demonstration of the conjecture was to place a straight stick or a taut thread next to the light beam,[10] to prove that light travels in a straight line.
Scientific methodology has been practiced in some form for at least one thousand years.[11] There are difficulties in a formulaic statement of method, however. As William Whewell (1794–1866) noted in his History of Inductive Science (1837) and in Philosophy of Inductive Science (1840), "invention, sagacity, genius" are required at every step in scientific method. It is not enough to base scientific method on experience alone;[12] multiple steps are needed in scientific method, ranging from our experience to our imagination, back and forth.
In the 20th century, a hypothetico-deductive model[13] for scientific method was formulated (for a more formal discussion, see below):
1. Use your experience: Consider the problem and try to make sense of it. Look for previous explanations. If this is a new problem to you, then move to step 2.
2. Form a conjecture: When nothing else is yet known, try to state an explanation, to someone else, or to your notebook.
3. Deduce a prediction from that explanation: If you assume 2 is true, what consequences follow?
4. Test: Look for the opposite of each consequence in order to disprove 2. It is a logical error to seek 3 directly as proof of 2. This error is called affirming the consequent.[14]
This model underlies the scientific revolution. One thousand years ago, Alhazen demonstrated the importance of steps 1 and 4.[15] Galileo 1638 also showed the importance of step 4 (also called Experiment) in Two New Sciences.[16] One possible sequence in this model would be 1, 2, 3, 4. If the outcome of 4 holds, and 3 is not yet disproven, you may continue with 3, 4, 1, and so forth; but if the outcome of 4 shows 3 to be false, you will have to go back to 2 and try to invent a new 2, deduce a new 3, look for 4, and so forth.
Note that this method can never absolutely verify (prove the truth of) 2. It can only falsify 2.[17] (This is what Einstein meant when he said, "No amount of experimentation can ever prove me right; a single experiment can prove me wrong."[18]) However, as pointed out by Carl Hempel (1905–1997) this simple view of scientific method is incomplete; the formulation of the conjecture might itself be the result of inductive reasoning. Thus the likelihood of the prior observation being true is statistical in nature[19] and would strictly require a Bayesian analysis. To overcome this uncertainty, experimental scientists must formulate a crucial experiment,[20] in order for it to corroborate a more likely hypothesis.
In the 20th century, Ludwik Fleck (1896–1961) and others argued that scientists need to consider their experiences more carefully, because their experience may be biased, and that they need to be more exact when describing their experiences.[21]
Tags:Science,Logic,Phenomena,Hypotheses,Experimental,Methodology,Ibn Al-haytham,Iraq,Islamic Golden Age,Galileo Galilei,Johannes Kepler,Book Of Optics,Arabic,Basle,Friedrich Risner,Syracuse,Archimedes,Roman Republic,Rainbow,William Whewell,Experience,Hypothetico-deductive Model,Affirming The Consequent,Scientific Revolution,Experiment,Two New Sciences,Falsify,Carl Hempel,Inductive Reasoning,Bayesian,Crucial Experiment,Ludwik Fleck,Truth,Certain,Explanations, | |
| DNA example | |
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Four basic elements of scientific method are illustrated by the following example from the discovery of the structure of DNA:
DNA characterization: Although DNA had been identified as at least one and possibly the only genetic substance by Avery, Macleod and McCarty at the Rockefeller Institute in 1944, the mechanism was still unclear to anyone in 1950.
DNA hypotheses: Crick and Watson hypothesized that the genetic material had a physical basis that was helical.[22]
DNA prediction: From earlier work on tobacco mosaic virus,[23] Watson was aware of the significance of Crick's formulation of the transform of a helix.[24] Thus he was primed to recognize the significance of the X-shape in photo 51, the remarkable photograph of the X-ray diffraction image of DNA taken by Rosalind Franklin.
DNA experiment: Watson saw photo 51.[25]
The examples are continued in "Evaluations and iterations" with DNA-iterations.[26]
Tags:Genetic,Dna,Avery, Macleod And Mccarty,Rockefeller Institute,Crick,Watson,Tobacco Mosaic Virus,Photo 51,Rosalind Franklin, | |
| Truth and belief | |
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Main article: Truth
In the same way that Alhazen sought truth during his pioneering studies in optics 1000 years ago, arriving at the truth is the goal of a scientific inquiry.[27]
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| Beliefs and biases | |
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Flying gallop falsified; see image below.
Belief can alter observation; human confirmation bias is a heuristic that leads a person with a particular belief to see things as reinforcing their belief, even if another observer might disagree. Researchers have often noted that first observations are often somewhat imprecise, whereas the second and third were "adjusted to the facts". Eventually, factors such as openness to experience, self-esteem, time, and comfort can produce a readiness for new perception.[28]
Eadweard Muybridge's studies of a horse galloping
Needham's Science and Civilization in China uses the 'flying gallop' image as an example of observation bias:[29] In these images, the legs of a galloping horse are shown splayed, while the first stop-action pictures of a horse's gallop by Eadweard Muybridge showed this to be false. In a horse's gallop, at the moment that no hoof touches the ground, a horse's legs are gathered together—not splayed. Earlier paintings show an incorrect flying gallop observation.
This image illustrates Ludwik Fleck's suggestion that people be cautious lest they observe what is not so; people often observe what they expect to observe. Until shown otherwise; their beliefs affect their observations (and, therefore, any subsequent actions which depend on those observations, in a self-fulfilling prophecy). This is one of the reasons (mistake, confusion, inadequate instruments, etc. are others) why scientific methodology directs that hypotheses be tested in controlled conditions which can be reproduced by others. The scientific community's pursuit of experimental control and reproducibility, diminishes the effects of cognitive biases.
Tags:Reproduce,Falsified,Confirmation Bias,Heuristic,Openness To Experience,Self-esteem,Eadweard Muybridge,Horse,Galloping,Needham's, | |
| Certainty and myth | |
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Any scientific theory is closely tied to empirical findings, and always remains subject to falsification if new experimental observation incompatible with it is found. That is, no theory can ever be seriously considered certain as new evidence falsifying it can be discovered. Most scientific theories don't result in large changes in human understanding. Improvements in theoretical scientific understanding is usually the result of a gradual synthesis of the results of different experiments, by various researchers, across different domains of science.[30] Theories vary in the extent to which they have been experimentally tested and for how long, and in their acceptance in the scientific community.
In contrast to the always-provisional status of scientific theory, a myth can be believed and acted upon, or depended upon, irrespective of its truth.[31] Imre Lakatos has noted that once a narrative is constructed its elements become easier to believe (this is called the narrative fallacy).[32][33] That is, theories become accepted by a scientific community as evidence for the theory is presented, and as presumptions that are inconsistent with the evidence are falsified. -- The difference between a theory and a myth reflects a preference for a posteriori versus a priori knowledge. --[citation needed]
Thomas Brody notes that confirmed theories are subject to subsumption by other theories, as special cases of a more general theory. For example, thousands of years of scientific observations of the planets were explained by Newton's laws. Thus the body of independent, unconnected, scientific observation can diminish.[34] Yet there is a preference in the scientific community for new, surprising statements, and the search for evidence that the new is true.[1] Goldhaber & Nieto 2010, p. 941 additionally state that "If many closely neighboring subjects are described by connecting theoretical concepts, then a theoretical structure acquires a robustness which makes it increasingly hard —though certainly never impossible— to overturn."
Tags:Knowledge,Empirical,Theories, | |
| Elements of scientific method | |
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There are different ways of outlining the basic method used for scientific inquiry. The scientific community and philosophers of science generally agree on the following classification of method components. These methodological elements and organization of procedures tend to be more characteristic of natural sciences than social sciences. Nonetheless, the cycle of formulating hypotheses, testing and analyzing the results, and formulating new hypotheses, will resemble the cycle described below.
Four essential elements[35][36][37] of a scientific method[38] are iterations,[39][40] recursions,[41] interleavings, or orderings of the following:
Characterizations (observations,[42] definitions, and measurements of the subject of inquiry)
Hypotheses[43][44] (theoretical, hypothetical explanations of observations and measurements of the subject)[45]
Predictions (reasoning including logical deduction[46] from the hypothesis or theory)
Experiments[47] (tests of all of the above)
Each element of a scientific method is subject to peer review for possible mistakes. These activities do not describe all that scientists do (see below) but apply mostly to experimental sciences (e.g., physics, chemistry, and biology). The elements above are often taught in the educational system as "the scientific method".[48]
The scientific method is not a single recipe: it requires intelligence, imagination, and creativity.[49] In this sense, it is not a mindless set of standards and procedures to follow, but is rather an ongoing cycle, constantly developing more useful, accurate and comprehensive models and methods. For example, when Einstein developed the Special and General Theories of Relativity, he did not in any way refute or discount Newton's Principia. On the contrary, if the astronomically large, the vanishingly small, and the extremely fast are removed from Einstein's theories — all phenomena Newton could not have observed — Newton's equations are what remain. Einstein's theories are expansions and refinements of Newton's theories and, thus, increase our confidence in Newton's work.
A linearized, pragmatic scheme of the four points above is sometimes offered as a guideline for proceeding:[50]
Define a question
Gather information and resources (observe)
Form an explanatory hypothesis
Test the hypothesis by performing an experiment and collecting data in a reproducible manner
Analyze the data
Interpret the data and draw conclusions that serve as a starting point for new hypothesis
Publish results
Retest (frequently done by other scientists)
The iterative cycle inherent in this step-by-step methodology goes from point 3 to 6 back to 3 again.
While this schema outlines a typical hypothesis/testing method,[51] it should also be noted that a number of philosophers, historians and sociologists of science (perhaps most notably Paul Feyerabend) claim that such descriptions of scientific method have little relation to the ways science is actually practiced.
The "operational" paradigm combines the concepts of operational definition, instrumentalism, and utility:
The essential elements of a scientific method are operations, observations, models, and a utility function for evaluating models.[52][not in citation given]
Operation - Some action done to the system being investigated
Observation - What happens when the operation is done to the system
Model - A fact, hypothesis, theory, or the phenomenon itself at a certain moment
Utility Function - A measure of the usefulness of the model to explain, predict, and control, and of the cost of use of it. One of the elements of any scientific utility function is the refutability of the model. Another is its simplicity, on the Principle of Parsimony more commonly known as Occam's Razor.
Tags:Physics,Chemistry,Biology,Social, | |
| Characterizations | |
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Scientific method depends upon increasingly sophisticated characterizations of the subjects of investigation. (The subjects can also be called unsolved problems or the unknowns.) For example, Benjamin Franklin conjectured, correctly, that St. Elmo's fire was electrical in nature, but it has taken a long series of experiments and theoretical changes to establish this. While seeking the pertinent properties of the subjects, careful thought may also entail some definitions and observations; the observations often demand careful measurements and/or counting.
The systematic, careful collection of measurements or counts of relevant quantities is often the critical difference between pseudo-sciences, such as alchemy, and science, such as chemistry or biology. Scientific measurements are usually tabulated, graphed, or mapped, and statistical manipulations, such as correlation and regression, performed on them. The measurements might be made in a controlled setting, such as a laboratory, or made on more or less inaccessible or unmanipulatable objects such as stars or human populations. The measurements often require specialized scientific instruments such as thermometers, spectroscopes, particle accelerators, or voltmeters, and the progress of a scientific field is usually intimately tied to their invention and improvement.
"I am not accustomed to saying anything with certainty after only one or two observations."—Andreas Vesalius (1546) [53]
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zote monety |