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“”Science is far from the perfect instrument of knowledge. It's just the best we have.
|—Carl Sagan. The Demon-Haunted World, Science as a Candle in the Dark|
The scientific method is an epistemological system for deriving and developing knowledge. It is considered the best method for making useful and practical additions to human knowledge about the physical world, and has resulted in the technological leaps made since it developed in the western world. At the core of the method is the idea that the value of a hypothesis, theory, or concept is best determined by its ability to make falsifiable predictions that can be tested against an empirical reality.
The scientific method means that supernatural entities or concepts that are meaningless or logically contradictory cannot be included in a scientific hypothesis (not least because you can't put a sample of a god in a test-tube). Consequently, when carrying out investigations scientists assume a position of methodological naturalism.
Humans, including scientists, are fallible and irrational apes by nature. The scientific method, therefore, helps these highly imperfect beings iron out their biases and develop good and useful results.
 How to do science
The scientific method isn't a simple, linear process, but is wrapped up in the complexities of research in the real world and the practicalities of what is possible. However, the idea of testing a hypothesis and refining knowledge based on observation is a constant theme of science.
Despite the lack of simple linearity in reality, the method has often been codified into stages that make it easier to understand. Essentially, the following five steps make up the scientific method:
- Observe - Look at the world and find a result that seems curious. As Isaac Asimov put it, "The most exciting phrase to hear in science, the one that heralds new discoveries, is not Eureka! (I found it!) but rather, 'Hmm... that's funny...'"
- Hypothesize - Come up with an explanation.
- Predict - The most important part of a hypothesis or theory is its ability to make predictions about result that have yet to be observed. These predictions should be falsifiable and specific.
- Experiment - Compare the predictions with new empirical evidence (usually experimental evidence, often supported by mathematics). This step is the reason why a hypothesis or theory has to be falsifiable – if you can't prove it wrong, you can't really prove it right. Information from these predictions can lead to a refinement of the hypothesis.
- Reproduce - ensure the result is a true reflection of reality by verifying it with others.
The testing of hypotheses allows for error correction and the development of better models. One of the notable examples is the development of atomic theory - the theory that describes what atoms "look like". From Dalton's indivisible model, to Thomson's "plum pudding" model, to Rutherford's teeny-tiny nucleus model, and then to the Bohr Model and modern quantum physics, the atom developed in steps because each model made predictive statements that could be tested. Thus the theory is refined over time and as observational evidence increases in support of it. That evidence supports a hypothesis implies that the hypothesis is stronger (and more likely to be valid) than before the test. On the other hand, evidence against a hypothesis makes it invalid, thus falsifying it. It is an inductive method, although its results can be used deductively as well.
All but the first two steps are omitted from the process in pseudosciences such as intelligent design (where step 3 would be impossible) and most borderline-supernatural alternative medicines like homeopathy. Pseudosciences do observe the world, and do come up with explanations, but are often unable or unwilling to follow through in testing them more thoroughly. Refining the hypotheses is also undesirable in pseudoscience as this could lead to abandoning the central dogma of the belief - imagine where modern technology would be if the scientists of the 20th century refused to modify the structure of the atom as new observational evidence came in? However, because observations and explanations still form a part of pseudoscience and can be phrased in a scientific style, pseudosciences may mistakenly appear to have scientific authority.
Galileo Galilei and Francis Bacon were among the first scientists to use the scientific method in the modern, western world, taking over from the Greek method that prioritised rational thought over empiricism. Prior to this, the scientific method was used widely in the "Islamic Golden Age", a time between the 7th and 12th Centuries and Arabic Science even generated a system of peer review. Arabic science went into a steady decline as the Mongol invasion ravaged the Islamic world in the 13th century. The scientific method was not always accepted during its period of development and the work of Ignaz Semmelweis provides a telling example of what happens when the method, or the conclusions arrived at by its use, are ignored.
Scientific skepticism is a vital element in the scientific process, ensuring that no new hypothesis is considered a Theory (capped T) until sufficient evidence is provided and other scientists have had their chances to debunk it. Even then, all of science is always considered a "good working model" and the "best understanding we have at the present time". No scientific idea is ever considered "the final word," nor the Word of God. It is always assumed that someone, somewhere is out to disprove the current theory.
 Philosophical perspectives
Philosophy of science dates back to the Greeks, but it began to take its modern form during the scientific revolution. Two competing schools of thought emerged at this point: The rationalist tradition associated with René Descartes and the empiricist tradition of Francis Bacon. During the 18th century, David Hume philosophically undermined the scientific method with his problem of induction and his deconstruction of causation. A synthesis of rationalism and empiricism arose in the 18th century with the work of Immanuel Kant and continued in the 19th century among pragmatist philosophers such as Charles Sanders Peirce. During the 20th century, the logical positivists attempted to do away with pesky metaphysics and a number of other branches of philosophy altogether. The enterprise failed when it was noticed that the verification principle it was built on was self-refuting. Karl Popper replaced verifiability with falsifiability, that is, for an idea to be "scientific" it must be possible to devise an experiment (even a thought experiment) that could render it false. Falsification was intended as both a solution to the demarcation problem and a workaround for Hume's problem of induction. Thomas Kuhn took a more historical approach, aiming to get a better picture of how science was practiced in reality. He described the dynamics of scientific change, coining the terms scientific revolution and paradigm shift to help described what he saw as the way a fundamentally conservative set of ideas could be overturned and become a new, different set of conservative ideas. Kuhn rejected the idea that there was only one scientific method. This influenced the practitioners of what would become the sociology of science as well as other philosophers, such as Imre Lakatos. Lakatos conceived of science as split into numerous paradigms he called "research programmes," each making use of its own methodology and assumptions. Summary: Humans remain humans and don't naturally think in a scientific manner, but have to learn it, and easily backslide.
There are other schools of "scientific criticism" that look at science critically from an economic perspective, or that focus on discourse, but these are more academic and less practical critiques.
 The problem of solipsism
Solipsism proposes that the only thing we can be sure of - i.e., the only thing that can be conclusively proven without any prior assumptions - is that we experience therefore we exist, in some form at least. The scientific method requires certain a priori assumptions of epistemology and metaphysics in order to even get out of the starting gate. It assumes you are not a brain in a vat and that Last Thursdayism does not apply. If you are trapped in some sort of Descartian nightmare of being certain of your own "existence" and rejecting everything else then there is nothing for science to do.
In order to demonstrate that the scientific method is the single best source for knowledge of the natural world, two major axioms have to be set. The first is that "some ideas are more wrong than others," and the second is that "our sensory experiences correlate with some sort of external reality". Specifically, the scientific method assumes these axioms because there is no reason or evidence available via the scientific method to say otherwise. This is slightly circular but it does lead to science being internally consistent. If you agree to those first assumptions regarding the nature of reality, the scientific methods falls out pretty quickly as the path to knowledge.
 Unintentional short circuiting of the scientific method
In order to look for "data" you need to have a model or "structure" of how the world works. The problem as James Burke pointed out in the "Worlds Without End" episode of Day the Universe Changed that structure can drive every part of your research even what you accept as reliable data.
This possibility of the structure driving the data rather than the data driving the structure had been hammered home in anthropological circles back in 1956 with Horace Miner's bitingly satirical "Body Ritual among the Nacirema"  Often referenced as a satirical look at American culture is "Body Ritual among the Nacirema" was also a satirical look at anthropological work of the time and the 'Look at these poor primitives who believe in magic that we are so much wiser than' attitude so common in professional publications of the time. Miner showed that with that model any culture even that of then modern 1950s United States could be dismissed as a bunch of magic using savages.
In "Worlds Without End" Burke points out one of the reasons the Piltdown hoax lasted as long at it did was it fitted the then prevalent structure of finding a human like skull with an ape like face. In fact, in 1923 Franz Weidenreich stated after careful examination that the Piltdown find was a modern human cranium and an orangutan jaw with filed-down teeth but because Piltdown fit the structure so well other scientists let the model drive their thinking rather then the evidence itself.
 Cheating the scientific method
Pseudoscientists have discovered an obvious way to 'cheat' the scientific method.
It goes like this:
- Pick a personal belief that you want to 'prove' is true.
- Make new observations or experiments, and note the results.
- Think up some clever way by which to shoehorn your personal belief to said results.
- Falsely claim that your personal belief predicts the particular results, and that the observations/experiment confirmed your suspicions.
This manner of cheating has been used by proponents of intelligent design.
Note that this isn't limited to pseudoscientists such as those trying to grant legitimacy to intelligent design, but is a mistake frequently made even by "proper" scientists, if they focus too much on finding evidence that supports their hypothesis (their "belief"), instead of focusing on attempting to find evidence that would refute it, or on attempting to find evidence that would refute competing hypotheses.
 See also
- Introduction to the scientific method, Frank Wolfs, University of Rochester
- In Our Time: The Scientific Method, BBC Radio 4
- ↑ It was also developed elsewhere, such as in the Islamic Golden Age, around 8th to the 13th Centuries in the Middle East - where Jābir ibn Hayyān developed experimental methods for chemistry. See Falagas et al 2006.
- ↑ Robinson, W. R. "The Inquiry Wheel, An Alternative to the Scientific Method." J. Chem. Ed. 2004(81): 791-2.
- ↑ As in, not the same one from the "observe" stage.
- ↑ That the scientific method works this way is implied by Bayesian mathematics.
- ↑ Amad Y Hassan. Factors Behind the Decline of Islamic Science After the 16th Century. History of Science and Technology in Islam
- ↑ The Problem of Induction: Hume, Induction, and Justification, Stanford Encyclopedia of Philosophy
- ↑ David Hume: Causation, Internet Encyclopedia of Philosophy
- ↑ Immanuel Kant, Stanford Encyclopedia of Philosophy
- ↑ Charles Sanders Peirce: Pragmatism, Pragmaticism, and the Scientific Method, Stanford Encyclopedia of Philosophy
- ↑ Interestingly, both the positivists and Popper acknowledged that their principles could not live up to their own standards (i.e., the principle of verification was itself unverifiable and falsification was unfalsifiable, but they did not consider this to be a problem.
- ↑ Miner, Horace (1956) "Body Ritual among the Nacirema" American Anthropologist Anthropologist 58:3, June 1956.
- ↑ MacRitchie, Finlay (2011). Scientific Research as a Career. CRC Press. p. 30. ISBN 1439869650.