I believe Aristotle’s idea of spontaneous generation is a good example. You might think this is ludicrous, but for thousands of years it was believed that life did not start from reproduction as we think today. This was Aristotle’s belief and it was based on the ideas of some philosophers like Anaximander, Hippolytus, and Anaxagoras who believed life arose from non-living objects like mud and slime when exposed to sunlight. Aristotle, as a conformist scientist also did his experimentation to further confirm this hypothesis. He was able to show that maggots spontaneously appeared on the carcasses of animals when left in sunlight. Some scientists after him used microscopes to view microorganisms but did not know where they came from. Unfortunately this became more evidence for spontaneous generation. However they believed big animals had parents. In the 1800s, the Paris Academy of Science offered a prize for whoever was able to carry out and experiment to resolve an argument between two scientists over this issue. Louis Pasteur claimed the prize by disproving Aristotle’s theory in an experiment where he put meat in a jar and left it for some days. Fortunately he covered one of the jars unlike the other scientists before him, and he observed there were no maggots in the sealed jar. This proved that the maggots could have only come from the bacteria in the atmosphere. This was further proven after the use invention of powerful microscopes. It was realised that the same insects which formed on the meat were also formed under the microscope by some micro-organism over time. I think this was believed because the observations of this experiment were everyday things. Whenever anyone left a dead animal on a dump site it developed maggots. I believe the empirical evidence provided was strong enough. A lot of experiments were conducted which just added more evidence to this belief. Also the development of microscopes in this era also allowed them to see micro-organisms, which worsened matters because they did not know how they came about.
D. B. Fankhauser, J. Stein Carter. “Spontaneous Generation.” 2 January 2004. Clermont College Biology . 2 February 2011 .

Mawupemor,

This is certainly a very interesting and relevant example. I would just add that it would be good if you could indicate clearly which parts of your post are taken from your source.

I would encourage you and everyone else to find out about the Italian scientist Francesco Redi and his experiment in the 17th century that first cast doubt on the idea of spontaneous generation. His experiment is often cited as the first truly SCIENTIFIC experiment - whether or not this is true (or whether we can ever know that for sure), what features of his simple investigation would support the idea that it was rigorously scientific?

It is easy to get the information about Redi - you know how! So let's see some replies in this, as well as other suggested responses to Thaler...

Aside Galileo, Francesco Redi was one of the scientists who challenged Aristotle's theories in the 17th century. He is known for challenging the theory of spontaneous generation and introduced the use of controlled experiments.

Redi disproved the theory of spontaneous generation, developed in Aristotle's time, which stated that living things could be generated from inanimate objects through a controlled experiment which was done to determine if maggots could be generated from meat.

He conducted this experiment by obtaining 8 jars which contained meat each, covering 4 with muslin and leaving the other 4 bare. At the end of the experiment, only the 4 setups which were not covered with muslin contained maggots in them. This sparked up the need for a control in every experiment that is conducted by a scientist, thus, placing Redi's experiment among one of the truly scientific experiments to be conducted. Redi contributed to the addition of an important criteria for the reliability of a scientific experiment, since controlled experiments are widely used and usually required by regulatory bodies.


To answer Thaler's question, a theory which was one considered true but has been recently disproved is the Phlogiston theory. The theory discovered by Johan Joachim Becher in 1667, stated that every material which was able to burn contained an element known as phlogiston, which was released during burning, and made the process of combustion possible. Phlogiston was said to be without color, odor or taste, but could only be visualized in flammable objects. The object was said to exist in its natural, true form, "calx", after all the phlogiston had been burnt out of the material. Aside explaining combustion, this theory also sought to explain the rusting of metals and also the process of breathing, as pure oxygen was referred to as "dephlogistated" air. However, in later years, it was realized that most of the experiments conducted using the phlogiston model were ludicrous. An example is it was realised that some metals gained weight when they were heated, rather than losing weight, if phlogiston was being given off. The idea was later abandoned and is now being explained by more reliable theories like oxidation.

That is also a very good example, Crystal.

Spontaneous generation -> cell theory
Phlogiston -> oxygen

Do you think these are examples of "paradigm shifts"? Why or why not?

I think both theories are paradigm shifts because they both have been nullified and are generally accepted in the scientific world to be false. There has been a shift in the originally held belief in these theories and now newer theories have been discovered to rectify the misconceptions and falsities in those originally held beliefs and explain the phenomena which led to the development of those theories.

Another theory which was once considered to be true but was disproved was Maternal Impression. This was an old belief whereby a mother's thoughts while pregnant could impart special characteristics onto the unborn child. For many years this theory was used to explain congenital disorders and birth defects.For example: Joseph Merrick, who was also known as The Elephant Man was a severely deformed man in the 19th century London. It was suggested that his mother was frightened by an elephant while pregnant and imprinted the memory of an elephant on her child. Also, mental problems such as schizophrenia and depression were believed to be manifested as a result similar disordered feelings in the mother.So if a mother experienced great sadness in her life while pregnant, it was likely that her child would suffer from depression in his/her life. However, this theory was abandoned and debunked in the 20th century due to the development of modern genetic theories, which explained the ideas of molecular structure and function of genes as well as heredity and variation in living organisms.

A couple of quotations from Kuhn himself.

First, perhaps this is what Hikari is suggesting happens most of the time in scientific work:

"'Normal science' means research firmly based upon one or more past scientific achievements, achievements that some particular scientific community acknowledges for a time as supplying the foundation for its further practice.

And then there is the question of how large a change needs to be for it to count as a paradigm shift:

"Scientific development depends in part on a process of non-incremental or revolutionary change. Some revolutions are large, like those associated with the names of Copernicus, Newton, or Darwin, but most are much smaller, like the discovery of oxygen or the planet Uranus. The usual prelude to changes of this sort is, I believed, the awareness of anomaly, of an occurrence or set of occurrences that does not fit existing ways of ordering phenomena. The changes that result therefore require 'putting on a different kind of thinking-cap', one that renders the anomalous lawlike but that, in the process, also transforms the order exhibited by some other phenomena, previously unproblematic."

Source for both quotations: http://www.todayinsci.com/K/Kuhn_Thomas/KuhnThomas-Quotations.htm

I think we must be careful to make a distinction - simply falsifying a hypothesis is not really a paradigm shift. Remember that a pardigm is a matrix of beliefs and assumptions, and a shift must disturb this matrix of acceptance. So let's take our examples and put our "scientific thinking caps" on: what associated beliefs and assumptions would have been disturbed by the coming of a correct understanding of oxidation, or of a true account of the origins of cells? How far would the ripples of change spread out across the field of knowledge?

A paradigm is "a view, interpretation and perception of the world" in all these cases,the scientists made observations and then tried to interpret it in a way sensible to THEM. Other scientists came around and interpreted these observations in a different light,as also most sensible to THEM, as in the case of the development of spontaneous generation. Since there has been a shift in these interpretations(which were made to the best of knowledge of both scientists)one can conclude on a case of paradigm shift. one must also not ignore the fact that their interpretations were also believed in for a long time before the other interpretations creeped in to prove theirs wrong.

Interesting stuff going on here. For the spontaneous generation example, I believe the paradigm shift was from believing that the "free air" as the scientists of that time called it, was the vital force in abiogenesis (Spontaneous generation) to accepting the maggots came from flies which laid their eggs on the meat. After Francesco Redi had performed his experiment where he put meat in jars and covered some of them with rubber bungs, the scientists who believed in biogenesis, disagreed with him based on the idea that the free air was the vital force in the spontaneous generation of life. So he performed the experiment again but this time covered some of the jars with muslin instead of a rubber bung to allow the free flow of air. However like the previous experiment, the one covered in muslin did not get any flies going in to lay eggs so it had no maggots. Even after this evidence, John Needham still opposed him by conducting an experiment where he used chicken broth and corn infusions. Even after heating, when he poured them into the jars, after some time he saw tiny organisms in the covered ones too. This gave him more reason to believe the organisms came spontaneously. However in recent times it has been realised that Needham did not heat his corn infusions well leaving some bacteria alive. I believe the paradigm here was the "free air" being a vital force in spontaneous generation, and it changed to biogenesis.

These are some very interesting contributions and I have one to add to the topics of discussion.
We all thought that there were 9 planets, until recently when it was discovered that Pluto may not necessarily be able to be classified as a planet. However, much before all of this, in 1843, a French mathematician, Urbain Jean Joseph Le Verrier found some unusual behaviour of the orbit of Mercury when he compared it to Newton's Law of Gravitation. His explanation for these peculiarities was that there was a planet between the sun and the moon. He named this planet Vulcan. After his "discovery" of Vulcan, there were even alleged observations of the planet as dark spots in front of the sun. The theory of Vulcan being an existent planet lasted for a little over 50 years, past the death of Le Verrier, until 1915 when Albert Einstein used his theory of relatively to explain the peculiarities in Mercury's Motion. The idea of Vulcan has not died out and there are still a few people who believe in it's existence.
Just thought it would be interesting to add that the creators of the popular TV show "Star Trek" decided to use the concept and name one of the main planets in the show after it.

The above are all most interesting examples. The challenge is to understand what each of them might show about the nature of science, beyond the obvious fact that some hypotheses turn out to be wrong, some ideas become obsolete. It is important to be able to relate them to the kinds of concepts we employ when discussing science in TOK, such as a paradigm, or the doctrine of falsification.

I think some of us have visited the web page at:

http://www.toptenz.net/top-10-most-famous-scientific-theories-that-turned-out-to-be-wrong.php

Does anyone have any comments for or against this web page as a reliable source for this topic?

I think this web page will indeed aid in finding examples that are related to the topic at hand. However I don't think it is reliable as a sole source of information. Even if one finds an example from one of their ten "Famous Scientific Theories That Turned Out To Be Wrong", I think it is necessary to conduct some further research on the example, to know exactly what it was about and if it is in accordance with Mr Kidane's request.

Hi everyone
As I science student I am very interested in the whole concept of paradigm shifts.
It fascinates me to know that just with one discovery, all the knowledge I have been taught all my life could be made irrelevant. It’s amazing how at a point in time scientist are so convinced in what they believe to the extent that any other idea that is brought up is viewed as nonsense. Galileo’s example is a big cliché but it proves how preconceptions, emotions and feelings should be set aside when it comes to studying the sciences. It also emphasis on the uncertainty of science since it could mean that a lot of things scientist observe are just observed in a particular way due to limitations in the apparatus and technology we possess .
Galileo Galilei (15 February 1564 – 8 January 1642), was an Italian physicist, mathematician, astronomer and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations, and support for Copernicanism.
Galileo's championing of Copernicanism was controversial within his lifetime, when a large majority of philosophers and astronomers still subscribed to the geocentric view that the Earth is at the centre of the universe. After 1610, when he began publicly supporting the heliocentric view, which placed the Sun at the centre of the universe, he met with bitter opposition from some philosophers and clerics, and two of the latter eventually denounced him to the Roman Inquisition early in 1615. In February 1616, although he had been cleared of any offence, the Catholic Church nevertheless condemned heliocentrism as "false and contrary to Scripture", and Galileo was warned to abandon his support for it—which he promised to do. When he later defended his views in his most famous work, Dialogue Concerning the Two Chief World Systems, published in 1632, he was tried by the Inquisition, found "vehemently suspect of heresy", forced to recant, and spent the rest of his life under house arrest.
I would like all of you to do something. Imagine there is nothing like gravity. And that the only reason what goes up comes down is because there are some certain obstacles which the human eye cannot view which pushes everything back down. Imagine it is some special type of gas which we feel as if it is normal air yet its only function is to bring as back to the ground when we jump. Or imagine that the only reason the earth isn’t colliding with the sun is that there are some special celestial bodies that occupy the space between the earth and the sun, some celestial body which can withstand the heat of the sun and be in close contact with it. Now imagine all of a sudden some genius comes up with some special eye piece that enables us to view these impossible things. What would become of our lifetime g=9.81ms-2 and all the so called calculations we have made. I know this is impossible but as scientist (future/current) we are supposed to be open-minded and accept what we think is not possible. We are supposed to be willing to get up one day and accept that “Pluto is a dwarf planet” or that the earth is not the centre of the earth.
It’s funny to think about how just one discovery can disprove something that was experimented on so many times that it moved on from a theory to a law. Many of us think that technology has reached its peak and that nothing else can be invented but believe it or not that is what was thought many years ago. Charles H. Duell, Commissioner, U.S. patent office, 1899 (attributed) once said “Everything that can be invented has been invented.” This obviously was not the case and is not the case now. I think we should be ready for future paradigm shifts. Kuhn used the duck-rabbit optical illusion to demonstrate the way in which a paradigm shift could cause one to see the same information in an entirely different way. What if really everything we are seeing, we are just seeing because we have been made to see that way?

sources
information about Galileo taken from www.wikipedia.com
Quote by Kuhn taken from www.wikipedia.com
quote by Charles taken from
http://www.quotationspage.com/quote/22779.html