TOK Certainty and Paradigm shifts

To what extent is Science true, or certain?

Some would say that Darwin's theory of evolution is a scientific fact, other claim that the evidence is insufficient. Using an entertaining video clip from Friends this activity explores the way that Science puts forward knowledge claims and to what extent Science can be true, or certain.  

Further research from an historical scientific lecture and quotes from famous scientists complete this activity which will provide students with some clear notes about the nature of scientific knowledge and some resources for a TOK presentation or ToK essay.


Activity 1:  Friends Episode

In this activity we will explore the nature of Scientific knowledge.

This clip from an episode of Friends explores the debate between those who see evolution as scientific fact and those who don't.  There are some excellent illustrations of the nature of scientific knowledge.

The key moment is when Ross admits that there is a 'teeny tiny possibility that evolution doesn't exist'

To Do

Watch this clip then complete some answers in the first ideas column of the worksheet.

Try to explain what you understand about the nature of Scientific knowledge as you answer the questions in the first column..

Activity 2: Science Lecture

Richard Feynman was a Nobel prize winner, a theoretical physicist and popular lecturer. His views on Science.back in the 1960s are still valid today.  This is a clip from a serious lecture and a real contrast to the Friends episode.  However, the content is surprisingly similar, although the example is not evolution.

To Do

Watch this video explanation of the scientific method and add details of your ideas to the worksheet.

Activity 3: Quotes on Science and Truth

There are thousands of quotes from famous scientists that can add to this discussion.  The worksheet includes a few examples, like the ones below.

To do

 Read the quotes on the last page of the worksheet and add your thoughts to the worksheet.


A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather its opponents eventually die, and a new generation grows up that is familiar with it.
— Max Planck                Scientific Autobiography and Other Papers, trans. F. Gaynor (1950), 33. 

<-- click the triangular play button to hear Max Plank 

...I believe there exists, and I feel within me, an instinct for the truth, ... something of the same nature as the instinct of virtue, and that our having such an instinct is reason enough for scientific research without any practical results.
— Charles Darwin             The Correspondence of Charles Darwin, Vol. 4. (1847-50) 

<-- click the triangular play button to hear Charles Darwin


Further Reading / Extension

Read the article Ancient Penguin DNA.

Can you determine how the researchers determined the chronological age of the fossils?  

With this article, you could discuss the idea of mutation clocks based on mutation rates.  On what basis are these clocks operating?  Is the data from the ancient penguins able to upset the mutation clock mechanisms scientists have been using?

What happens when long established ideas are put into question?  This is often referred to as a "Paradigm shift".  What other paradigm shifts have occurred in Biology and what provoked each one?

For example, until 1665 all that we knew about organisms was that they had organs inside.  Along comes Robert Hooke who first described cells in cork tissue.  His use of a microscope allowed him to see what had never been seen before.  Not long after that Anton van Leeuwenhoek described single celled organisms or "animalcules".  This was revolutionary as no one had seen organisms so small.

Of course this lead on to the development of the cell theory, the abolishment of the idea of spontaneous generation, the development of the germ theory from the works of Louis Pasteur and Robert Koch.  All through the 1880's to 1950's discovery after discovery of the organelles provided the stimulus for more and more research into cell structure and function. 

Climate Change

Scientists grapple with the disparity of data supporting Global warming.  This links to Topic 5.2 Greenhouse Gases.   The evidence seems conclusive so why is there still doubt.
There is a good discussion from the Economist here and you can read the related article here

Description: Teachers notes about how to use the activity.


To understand what is meant by Scientific Fact and that Science is never 100% certain.

Activity 1:  (15- 20  minutes)

Student's watch the short Friends video clip and try to answer the questions in the worksheet, recording answers in the second column called 'First Thoughts'

It is a good idea to check that everyone has completed some of these points and understands the issues before starting acticity 2.

Activity 2:  (20 minutes)

Using the second video clip of the historical lecture Feynman made about the scientific method students add some further scientific examples of the problems of scientific knowledge.  

Record answers / notes  in the third column of the worksheet

See the suggestions in the teachers reference sheet, but these are only suggestions.  

Activity 3; (15 minutes)

Read the quotations and add some notes about the views of these scientists into the last colum of the worksheet.  These notes could be linked to the quotation in a TOK essay.

Plenary / General Points

  • Science is never 100% certain.
  • Vague untestable hypotheses cannot be called science
  • Some scientific theories have not yet been fully tested.
  • Scientific theoies gradually get refined over time.

Extension Ideas

Recent evidence from DNA analysis has further supported the theory evolution of natural selection.  The Further reading about mutations in Penguins gives just one example of this.

Scientists grapple with the disparity of data supporting Global warming.  This links to Topic 5.2 Greenhouse Gases.   The evidence seems conclusive so why is there still doubt.
There is a good discussion from the Economist here and you can Read the related article here

David Faure, 2012.

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