1

2

Describe this picture?

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Describe this picture?

<Mother and Son>

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• 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.

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On March 18, 2003

Pathology DepartmentSingapore General Hospital

Singapore’s Defence Medical Research Institute

National Microbiology LaboratoryWinnipeg

Institute for Medical Virology, Goethe University, Frankfurt

Bernhard Nocht Institute, Hamburg

CUHK

Paramyxovirus

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On March 21, 2003Institute for Medical VirologyGoethe University, Frankfurt

HKU

National Influenza CentreErasmus University, Rotterdam

CDCAtlanta, Georgia

HK Government Virology Lab

Coronavirus

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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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Coronavirus

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. 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!

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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?

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What have you learnt about the nature of science?What have you learnt about the nature of science?

Scientists aim to be objective, however Scientists aim to be objective, however observations are observations are theory-ladentheory-laden

Scientific knowledge is Scientific knowledge is tentativetentative It It changeschanges due to new evidence and new ways due to new evidence and new ways

of looking at existing evidenceof looking at existing evidence

SummarySummary

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Acknowledgements

Prof. Dennis Lo

Department of Chemical Pathology,Faculty of Medicine,The Chinese University of Hong Kong