Natural Science

What is Science?• ‘Science’ can be defined simply as a methodology of

testing knowledge claims through empirical observation (experimentation)– Hypothesis– Experimentation– Analysis of results– Develop scientific laws– Develop scientific theories– Repeat the cycle

• This is integrated with publication, peer review, replication and falsification

‘science’ is therefore not really just a body of knowledge, as is commonly thought

The Scientific Method Law

Hypothesis (must be falsifiable)

Experiment (with independent, dependent and control variables)

Conclusion

Theory

Peer review, replication of experiments, scrutiny by the scientific community and attempts at falsification

A paradigm shift may (but not always) lead to changes in scientific laws

The Scientific Method

• The scientific method is a fairly simple idea

• But it took us over 2000 years to perfect it

• In fact, the last piece was only added in the 1960s when Karl Popper (1902-1994) proposed the principle of falsification

The Scientific Method• The principle of falsification dictates that a scientist should abandon a theory

when it is falsified

• Sometime this doesn’t happen - it may be difficult for a scientist to admit their (lifetime’s?) work is incorrect

• However the falsification itself may be incorrect (or limited by available information):– When Newton was asked why gravity did not cause the Universe to collapse he stated

that God was counteracting it (we now know the Universe is actually expanding, overcoming gravitational attraction between galaxies)

– When Mendeleev saw that some atomic masses did not fit into his periodic table, he concluded that experimental error was to blame (it was actually due to the occurrence of isotopes)

– Lord Kelvin had measured the rate of cooling of the Earth and concluded (incorrectly) that the Earth was approximately 100 million years old. When Darwin realised this would mean the Earth was too young to support his theory of evolution by natural selection, he merely stated that Kelvin was wrong Therefore, is there a level of subjectivity to the Popper’s principle of falsification?

What is Pseudoscience• When a knowledge claim purports to be scientific but does not meet

the requirements of the scientific method, we label it pseudoscience

• Such claims are often falsifiable or make such vague claims that they cannot be falsified (often supporters simply reject any falsification)

• They are often based on belief systems which are not supported by empirical observation

• While a good scientist (hopefully) should reject a hypothesis if it is falsified, a pseudoscientist will often introduce ad hoc exceptions to avoid doing so http://edrontheoryofknowledge.blogspot.mx/2013/12/the-difference-between-quantum.html

However, just because something is not scientific does not mean it is automatically pseudoscientific. A pseudoscience claims to be scientific when it is not

A Scientific Knowledge Claim

Is this scientific?

Two Different Ideas

• The Story of Creation in Genesis

• Darwin’s Theory of Evolution by Natural Selection

Which is scientific and why?

Pseudoscience or science?

• Acupuncture• Astrology• Intelligent design• Crystology • Feng shui• Graphology• Homeopathy• Phrenology

If it works for people, why bother about whether it is scientific or not?

But if it works then surely we should find out WHY. Won’t this then involve a scientific hypothesis and testing and therefore make it scientific?

Can something be unscientific but NOT pseudoscience

Can something that has been regarded as pseudoscience become accepted as science?

Science• Name as many sciences as possible

• What do they have in common?

• Science is thought of as being based on inductive logic (observing the general and moving towards the specific) – in other words, it is knowledge through verification

• However, in his essay ‘Science as Falsification’ Karl Popper showed that scientific conclusions are reached via falsification rather than verification

• Therefore the scientific method is not entirely inductive

The Problems of Science• Since science is based on empirical observation, it is affected by the

problems that beset observation:

– Sometimes your expectations can lead you to see things that are not really there. e.g. Planet Vulcan

– Acceptance of expert opinion or a fixed idea can lead you to not see (or overlook) things that are really there. e.g. in May 1952 (a year before Watson and Crick made their model) Rosalind Franklin had all the evidence she needed to conclude that DNA was a double helix, but she didn’t interpret the information correctly

– The act of observation itself has an effect on results (the observer effect). e.g. placing a thermometer in a liquid affects the temperature of the liquid

– There are some things that the human brain doesn’t seem to be able to understand (or things that lie outside our experience). e.g. The Bell Experiment

Rationalism vs. Empiricism• Rationalists look to reason to support knowledge claims while empiricists embrace

experience (observation)

• You might think this is the same thing, but while a rationalist would support a beautiful theory over observational evidence, an empiricist would support the observation over the theory (falsification)

• The correct stance in terms of the scientific method is really to be empirical. Reason is limited by unconscious prejudices (although you could argue that our sense perception has similar problems)

• In practice, science progresses through an uneasy mixture of rationalism and empiricism

• This introduces problems into our idea of falsification. While a scientific theory can never be proved (certainly not in the same way as a mathematical theorem), perhaps it may not be possible to properly falsify either. However, be careful not to equate this to relativism

Perhaps Newton, Mendeleev, Darwin and Einstein were rationalists rather than empiricists. When Einstein was asked what he would have felt if Eddington’s observations had failed to support his Theory of General Relativity, he said “Then I would feel sorry for the Good Lord. The theory is correct.” (Einstein was, after all, an ‘armchair theorist’)

The Nature of Scientific Discovery• Paradigm ‘A framework of belief, usually applied to ruling

theories of science’

• Paradigm shift ‘A complete change from one paradigm to another, due to a major change in scientific thinking’

• The term was first used by philosopher Thomas Kuhn in his book ‘The Structure of Scientific Revolutions’ (1962)

• Kuhn used the duck/rabbit illusion to show how a paradigm shift could lead to you seeing the same information in a completely different way

Examples of Paradigm Shifts in Science• The Copernican Revolution• The replacement of phlogiston theory with Lavoisier’s ideas

of chemical reactions (‘The Chemical Revolution’)• The publication of On The Origin of Species by Charles Darwin• The acceptance of Mendelian inheritance rather than

Darwin’s idea of ‘pangenesis’ (the idea that all of the characteristics of a parent are heritable)

• From Newton’s idea of gravity to Einstein’s view of relativity • Publication of Heisenberg’s Uncertainty Principle• The elucidation of the structure and function of DNA

Note that paradigms exist in all areas of knowledge, not just natural scienceWe associate paradigm shifts with the idea of ‘genius’Note that the IB does not like you to use clichéd examples of paradigms in your essay

Recognising a Paradigm Shift• Sometimes a paradigm shift occurs very suddenly – e.g. Sir

Arthur Eddington proved Einstein’s Theory of General Relativity correct by observing a solar eclipse on 29th May 1919

• Sometimes it takes time for scientists to recognise a paradigm shift. Thomas Kuhn likened this to religious conversion

• Sometimes claims are made for a paradigm shift which the scientific community rejects. e.g. homeopathists claim that their remedies work because water molecules have a ‘memory’ of a cure and pass this on to their patients. This would require a new paradigm in chemistry and biology to be correct

Reaction to Paradigm shifts• Reaction to a paradigm shift can be very negative, sometimes violent and

sometimes very long-lasting (often in opposition to the scientific evidence)

• e.g. The Catholic Church condemned Copernicus and imprisoned Galileo

• e.g. There is widespread opposition to the teaching of evolution in schools

• On 31 October 1992, Pope John Paul II expressed regret for how the Galileo affair was handled, and officially conceded that the Earth was not stationary, following a study conducted by the Pontifical Council for Culture

(Galileo was kept under house arrest by the Church from 1633 until his death in 1642)

• On 15 February 1990, in a speech delivered at the University of Rome, Cardinal Ratzinger cited current views on the Galileo affair as forming what he called "a symptomatic case that permits us to see how deep the self-doubt of the modern age, of science and technology goes today“

• He stated that the treatment of Galileo by the Inquisition was “rational” and “just”

Progress in Science• Kuhn claimed that progress in science is punctuated - i.e.

there are periods of crisis which result in scientific revolutions

• He stated there are periods where paradigms exist together and scientists must choose between them. At other times scientists simply work within the existing paradigm without even questioning it

• Popper felt that scientific progress was much smoother with new paradigms being accepted much more easily into the body of scientific knowledge

Interestingly, a similar argument exists in evolutionary biology - Stephen Jay Gould developed a theory of punctuated equilibrium in which evolution occurs in marked jumps. Richard Dawkins believes gaps in the fossil record which support this are due to migration events

Reductionism• Reductionism is an approach to building descriptions of

systems out of the descriptions of the sub-systems that they are composed of

• Biology: atoms form molecules form organelles form cells form tissues form organs form organ systems form bodies form species form communities ….and so on

• Physics: atoms form molecules form minerals form rocks form planets form solar systems form galaxies… and so on

• The idea is that if we fully understand atoms we can understand basic systems, and then we can understand the systems that are formed from them

Chaos Theory• In mathematics and science, chaos theory describes the behavior of

certain systems which evolve with time – these may be highly sensitive to initial conditions (popularly referred to as the butterfly effect)

• This occurs due to the exponential growth of perturbations in the initial

conditions and the behavior of chaotic systems appears to be random

• This happens even though chaotic systems are deterministic (their future dynamics are fully defined by their initial conditions with no random elements involved)

• Chaotic behavior is also observed in natural systems, such as the weather, and mathematical patterns such as fractals

http://edrontheoryofknowledge.blogspot.mx/2012/11/chaos-theory-and-butterfly-effect.html

Emergence

• The observation that from chaotic behaviour, order can spontaneously arise. Examples include hive behaviour of insects, schooling of fish, flocking of birds and even the predictable movements of a crowd of people

http://edrontheoryofknowledge.blogspot.mx/2014/08/emergent-behaviour.htmlhttp://edrontheoryofknowledge.blogspot.mx/2009/05/what-are-emergent-properties.html

The Game of Life• The Game of Life is a computer simulation devised in the

1960's by the mathematician John Horton Conway. It's a very good example of how a few simple rules can quickly create order out of chaos, resulting in emergent behaviour. The simulation takes place on a 2-dimensional grid divided into cells. Each cell has eight neighbouring cells and can be either "alive" or "dead". The rules which determine it's fate are very simple:

• 1. If a cell has one or no living neighbours, it will die of loneliness.2. If it has too many neighbours - four or more - it will die from overcrowding.3. New cells are "born" whenever an empty square has exactly three living neighbours.

http://edrontheoryofknowledge.blogspot.mx/2009/05/the-game-of-life.html

Science and Truth• Science is a tool for getting closer to the truth

• There are problems involved in falsification and a scientific theory by definition can never be claimed as fact (some people think the use of the word ‘theory’ in science equates to a lack of certainty)

• However, perhaps paradoxically it is the best method we have for approaching truth about our observations of the Universe around us

• If a scientific theory has supporting evidence, corresponds to previous knowledge, coheres to the current paradigm and is pragmatic then we can accept it as true (at least until a better version of the theory comes along or there is a paradigm shift)

“Science does not aim at establishing immutable truths and eternal dogmas; its aim is to approach the truth by successive approximations, without claiming that at any stage final and complete accuracy has been achieved.”- Bertrand Russell