Infectious diseases

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Activity 3
How did the SARS scientists work?
Part 2
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• Describe this picture?

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ltMother and Songt

• Describe this picture?

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• Observations are affected by ones background
  knowledge and what one wants to see
• We can describe it as observations are theory
  laden
• Discussion
• In the following two slides we will look at how
  different scientists came up with two different
  claims for the pathogen causing SARS, try and see
  if you notice some theory-laden observations.

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On March 18, 2003
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On March 21, 2003
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Discussion Time
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Do you notice?

• Once the possible pathogen causing SARS was
  identified and announced, other groups would
  quickly read of its existence
• Their observations were biased by what they were
  prepared to see or what other scientists may have
  seen earlier
• - Observations are theory laden -

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• In the story of different scientists coming up
  with two different claims for the pathogen
  causing SARS, what else can you say about the
  nature of science apart from Observations are
  theory laden?
• Hint The identity of the SARS virus?

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• Got the answer already? If not, watch the
  following video and think again.
• Post-video discussion
• After scientists have developed a scientific
  theory or a scientific law, does the theory/ law
  ever change? Why?

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Paramyxovirus
new evidence
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Discussion Time
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• Scientific knowledge changes or evolves due to
• New discoveries
• Advances in technology
• New ways of looking at existing evidence

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How about the story of a recent Nobel prize
winner Dr. Barry Marshall

• For many years, doctors thought that stomach
  ulcers were a lifestyle disease. It was said to
  be stress that caused excessive secretion of acid
  in the stomach.
• However, Dr. Barry Marshall suspected that the
  bacteria he found in patients stomachs might be
  causing the ulcers.
• Homework How would you get evidence for Dr.
  Marshalls hypothesis?

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The story of stomach ulcers
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Discussion( Extension Activity )

• It took more than 10 years for Marshalls ideas
  about the role of bacteria in formation of ulcers
  to be generally accepted! Why? Check it out on
  internet!
• What elements of the nature of science can you
  find in Dr. Marshalls story?

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Summary

• What have you learnt about the nature of science?
• Scientists aim to be objective, however
  observations are theory-laden
• Scientific knowledge is tentative
• It changes due to new evidence and new ways of
  looking at existing evidence

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Acknowledgements
Prof. Dennis Lo Department of Chemical
Pathology, Faculty of Medicine, The Chinese
University of Hong Kong