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2 Describe this picture?

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4 Observations are affected by one’s 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.

5 On March 18, 2003 Pathology Department Singapore General Hospital Singapore’s Defence Medical Research Institute National Microbiology Laboratory Winnipeg Institute for Medical Virology, Goethe University, Frankfurt Bernhard Nocht Institute, Hamburg CUHK Paramyxovirus

6 On March 21, 2003 Institute for Medical Virology Goethe University, Frankfurt HKU National Influenza Centre Erasmus University, Rotterdam CDC Atlanta, Georgia HK Government Virology Lab Coronavirus

7 Discussion Time

8 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 -

9 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……?

10 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?

11 Coronavirus Paramyxoviru s new evidence

12 Discussion Time

13 Scientific knowledge changes or evolves due to: - New discoveries - Advances in technology - New ways of looking at existing evidence

14 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. Marshall’s hypothesis?

15 The story of stomach ulcers Medicine can only relieve your pain, it can’t cure stomach ulcer. How can there be so many bacteria in such an acid environment? Perhaps over secretion of gastric juice is caused by bacteria and not stress. This antibiotic should work. Great! The antibiotic can cure gastric ulcer. My theory is right!

16 Discussion( Extension Activity ) It took more than 10 years for Marshall’s 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. Marshall’s story?

17 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 It changes due to new evidence and new ways of looking at existing evidence Summary

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