2. Authorship
Who says so?
Authority
Who is he/she?
Are his/her views
shared?
Accuracy
Provenance
Evaluating
evidence’s
credibility &
relevance
Is it accurate?
Is this a primary or a
secondary source?
Nature
Facts or opinions?
Context
When was it reported?
Is it focussed?
Is it representative?
3. How to assess arguments?
5 Steps:
1
STRUCTURE
2
CLARITY
3
EVIDENCE
4
LOGIC
5
EVALUATION
4. Step 1
STRUCTURE
Identify:
• Evidence
• Conclusion
Two thousand years ago, the Earth was home to just 300 million humans, roughly the
population of the United States today. Two hundred years ago, 1 billion humans lived
on our planet Earth. The world population is now at over 6 billion and growing rapidly.
Thus, if current trends continue, we will add another 1 billion to the world population
every 13 or 14 years.
(Extract from www.umac.org/ocp/CausesofGrowth/info.html)
7. Step 4
LOGIC
Identify fallacies
Fallacy
Misleading or unsound argument
Formal fallacies
Mistakes in logic that are
independent of the
argument’s content.
(Flaws in the form of the
argument)
Informal fallacies
Mistakes in logic that
arise from the content.
(Flaws in the content of the
argument)
8. Informal fallacies
• False dilemma
(offers only 2 options when many more are possible)
“To lose weight, you either stop eating fries or have liposuction”
• Correlation proves causation
(assumes that correlation between two variables implies that one causes the other)
“Whenever I clean my car, it rains.”
• Cherry picking
(Only uses evidence that seem to confirm a particular position, while ignoring a significant portion of evidence
contradicting that position)
9. Informal fallacies
• Ad Hominem
(attacks the opponent rather than the argument)
“What does Prof Popper know about global warming? She drives a Range Rover”.
• Appeal to motive
( questions the motives of the proposer to dismiss the proposer’s point )
“Of course Prof Popper says climate change is dangerous! She holds the Chair of
Innovation in Heuristic Climate Change Modelling”.
• Appeal to emotions (uses emotion rather than evidence)
“We must stop climate change or your children will drown under rising sea levels”
• Straw man
(misrepresents the opponent’s argument)
“Prof Popper believes that an increase in rainfall will destroy crops but if there was no rainfall crops
would not grow in the first place”
10. How to assess arguments?
5 Steps:
1
STRUCTURE
2
CLARITY
3
EVIDENCE
4
LOGIC
11. Step 5
EVALUATION
Is the argument clear, with
valid evidence and logic ?
No
Yes
Strong
argument
Weak argument
12. How to assess arguments?
5 Steps:
1
STRUCTURE
2
CLARITY
3
EVIDENCE
4
LOGIC
5
EVALUATION
