2. Critical thinking is...?
Critical thinking is a way to think about ideas. These
could be ideas you’ve come up with or ideas you’ve
heard or read. It covers a range of values, skills and
knowledge.
What a good idea!
Good ideas are based on accurate information. They can be used
to make decisions that are as predictable as possible.
Bad ideas can be based on information that is misleading or
wrong. Making decisions using a bad idea might end up
causing you to take wrong actions, or cost you more than
you’re willing to pay!
3. Don’t I already think well?
Your brain evolved to take in
information and use it to make
sense of your surroundings.
However, it requires a lot of
energy to do this.
So your brain uses a number of shortcuts to save energy. They work well
most of the time, but on some occasions it makes you more confident in an
idea than you should be.
4. Brain cheats!
Illusions are a result of your brain taking a shortcut.
Do these horizontal parallel lines look straight to you?
5. Elements of critical thinking
Critical thinking involves a variety of skills, values and knowledge.
Skills are thinking processes. They can involve the ability to:
• Reflect analytically
• Imagine broadly
• Relate to other people
• Communicate clearly
• Identify context and bias
• Apply logic effectively and recognise the application of poor logic
6. Elements of critical thinking
Knowledge: describes facts and theories such as:
• The structure of logic
• Measured observations
• Contemporary scientific theories
Values: are concepts you think are important.
They can involve an appreciation of:
• The diversity of ideas people can have
• The right to respectfully be critical of other’s ideas
• That good ideas depend on accurate information
• The usefulness of logic in forming new ideas
• That all people can have confidence in bad ideas
7. Activity 1 & 2: What do we value?
Values are what inform our decision making. Sometimes we might put a
priority on friendship, while other times it might be wealth. We might like
to put a value on thinking reasonably, but sometimes our fear or our
faiths and beliefs might take priority instead.
Knowing how to understand our own values and those of others is
important in making good decisions.
Read the Activity 1 & 2 handout: ‘What do we value?’ and complete the
exercises
Extension: Find a newspaper article or a ‘letter to the editor’ that you
disagree with.
Identify what values differ between you and the article’s author.
9. That’s debatable!
Your parents and teachers might not like you arguing, but in
critical thinking, knowing what makes for a good argument is
important.
An argument is a structured response to an idea that shows why
you should (or shouldn’t) have confidence in it.
It is made of two parts: premises and a conclusion.
• Premises are ideas that are already presumed be true.
• The conclusion is the idea to be accepted as true or false.
10. A valid argument
An argument is valid when:
a) It has a logical structure
b) Its premises are accepted as true
12. A valid argument
An argument is valid when:
a) It has a logical structure
b) Its premises are accepted as true
Example
Premise 1: Magnets attract iron
Premise 2: This object is made of iron
Conclusion: Magnets will attract this object
Both premises are accepted as true, and the relationship between the
premises and the conclusion is logical.
13. Invalid arguments
Arguments can be invalid if the relationship between the premises does
not lead to that conclusion.
Think of mathematical equations; just as 3 + 2 does not equal 1, an
incorrect relationship between premises will make a conclusion incorrect.
14. Invalid arguments
Example
Premise 1: Magnets attract iron
Premise 2: The object in my hand is attracted to a magnet
Conclusion: The object in my hand must be made of iron
While premises 1 and 2 are correct, they don’t combine to produce that
conclusion. In this case, the premises don't exclude the possibility that
other materials are also attracted to magnets.
15. False premises
Arguments can have a good logical structure but have false premises.
True premises come in three varieties:
• Axioms (self-evident truths, such as 'all squares have four sides')
• Observed facts
• Valid conclusions from other arguments
Critical thinking involves the ability to identify how likely it is a premise is
true or false.
16. Activity 3
Read the following four arguments.
Three of them are invalid.
Identify the invalid arguments and state whether the logic is flawed or the
premises are incorrect:
17. Argument 1
Premise 1: Jack started school in June.
Premise 2: Things started going missing from the change rooms
in July.
Conclusion: Jack is a thief.
18. Argument 2
Premise 1: Scientists rubbed nano-particles into the skin of the
mice.
Premise 2: The mice got cancer.
Conclusion: Humans can get cancer from nano-particles.
19. Argument 3
Premise 1: Bacteria are defined as prokaryotes.
Premise 2: Prokaryotes are defined as having no nucleus.
Conclusion: Bacteria do not have a nucleus.
20. Argument 4
Premise 1: All teachers are female.
Premise 2: Bill is a teacher.
Conclusion: Bill is female.
21. Answers
Argument 1
Invalid. Premises might be true, but there are other possible reasons
explaining why things started to go missing in June.
Argument 2
Invalid. Premises might be true, but humans and mice aren’t the same
animals, therefore logically the two premises aren’t comparable.
Argument 3
Valid. Premises are true and the conclusion follows from them.
Argument 4
Invalid. The structure is logical, but premise 1 is false – not all teachers are
female.
22. Video
Watch Video 3:
The man who
was made of
straw
23. Activity 4
Read the following four arguments and counter arguments. Each counter
argument is either off-topic, over simplified, exaggerated or subtly twisted,
identify which and why you think so.
24. Argument 1
Argument: The use of nanotechnology in products comes with benefits
and risks. We should continue research in nanotechnology so we can
understand what is safe and what is not.
Counter-Argument: Nanotechnology comes with risks, and knowing
what those risks are will allow people to misuse the technology.
Research into nanotechnology should be stopped.
25. Argument 2
Argument: We’re pumping more and more carbon dioxide into the air,
these gases trap heat in the atmosphere, and so through our actions
we are heating the planet. We must do something to reduce carbon
dioxide emissions and slow global warming.
Counter-Argument: Carbon dioxide is also absorbed by plants; more
carbon dioxide will just mean more plants. This cancels out any
concerns about global warming because the extra carbon we make
won’t stay in the atmosphere.
26. Argument 3
Argument: While there are ethical concerns regarding the use the
embryonic stem cells, research in this area could help improve the
lives of many people. We should continue with research in this area.
Counter-Argument: The world is over populated as it is. Medical
research just extends lives, leading to more over population. It’s
unnatural that we live so long, research in this area should be
stopped.
27. Argument 4
Argument: In law, a patent protects people’s work by giving them
exclusive rights to it. It costs a lot of money to isolate and identify
genes, and therefore it’s only right that you can patent genes. It
protects your investment.
Counter-Argument: Patenting genes means owning something which is
naturally occurring. Pretty soon only a handful of biotechnology
companies are going to own all our genetic material. Patenting of
genetic material should be stopped.
28. Answers
Argument 1: The counter-argument is overly simple.
Argument 2: The counter-argument twists facts to draw its conclusion.
Argument 3: The counter-argument is off topic. Ignoring the issue of ethics in
embryonic stem cell research to focus on over population issues.
Argument 4: The counter-argument exaggerates the issue at hand.
29. That’s debatable!
Extension: Are there parts of the counter-arguments that you found you
would like to agree with? How do these counter-arguments match
with your values from Activity 1?
Visit education.technyou.edu.au/critical-thinking and follow the links
to Wikipedia articles to find the arguments for and against these
issues. Also view the Discussion page on each issue to follow the
ongoing arguments between the writers of these articles.
Now write better arguments (for or against) the arguments presented
in Activity 3. Discuss with your class.
30. Social thinking
Your brain is a complex organ. However it is an organ nonetheless. It
evolved to work cooperatively with other brains, which means it uses
thinking tools that work well in groups.
The upside is that there is safety in numbers. The downside is that it
produces biases. These help us cooperate with people who share our
values and beliefs. But it also means we are more likely to dismiss the
ideas of people who we don't like or trust, or whose values aren’t the
same as ours.
Unfortunately this can persuade us to overlook invalid arguments, or to
dismiss valid arguments prematurely.
32. Social thinking
What sort of social factors affect our thinking?
Authority: We rely on experts who spend time researching facts to come
to conclusions. Identifying informed experts amongst a range of 'talking
heads' is a vital skill in today's world.
Popularity: Ideas we hear from people we view as friends or celebrities
are more easy to accept as valid.
Exclusivity: Ideas we hear from people we view as bad or our enemy are
more difficult to accept as valid.
Equivalence: Everybody has an equal right to hold an opinion. But not all
opinions are equally likely to prove to be right.
33. Activity 5
Rank from 1 to 10 (1 being least, 10 be most) whose opinions you value.
Business Executive, Government Official, Politician, TV Journalist, Blogger,
Friends, Teacher, Family Members, Environmental Activist, Scientist
Do these people have similar values to you?
Do you consider them experts?
What issues would you approach these different people about?
What additional people would you add to this list?
34. Misleading patterns
Our brains are good at identifying patterns in nature. Sometimes, they are
too good at identifying patterns and can see things that aren’t there.
In the following sequence of coin flips, which face is most likely to come
up next?
HHHHTHTTHHHTTTTTTHHTTTHHHTTTTTTTTT ?
35. Misleading patterns
Which of these three answers matches yours?
C. Either: Heads or tails are equally likely
D. Tails: It is having a good run
E. Heads: It is due to come up
The last two answers is known as the gambler's fallacy. The right answer is A.
It can be difficult to appreciate how probability works. Our difficulty
distinguishing what is probable from what is possible makes us identify
patterns in sequences where there are none.
37. Confirmation bias
Confirmation bias is a tendency we have to subconsciously look for
patterns that confirm ideas we already suspect are true. This means we
will be more likely to see sequences of events or listen to arguments that
support our point of view.
Unfortunately, if our idea is a bad one, it makes it less likely we’ll spot the
flaws in our arguments.
Critical thinking involves challenging our ideas. This often means asking
what the world would look like if our argument was wrong, and looking
for ways to disprove rather than prove our ideas.
38. Effective communication
While jargon, metaphors or even mathematics are
often useful in communicating ideas, they can
sometimes be confusing or misleading.
For example, metaphors are phrases or words that
compare a new idea with one you already know.
However they can sometimes imply unwanted
meaning.
DNA is like a ‘code’ where four base chemicals are
arranged in a sequence.
Codes are messages intentionally written. DNA might
be like a code, but that does not mean somebody
wrote it.
39. Who argues?
When is it important to be able to make a good argument?
Any time you need to persuade somebody that an idea is useful in making
a decision, it needs to be supported by a logically sound argument.
This is called the burden of proof. Even if you need to convince yourself
that your own idea is reliable, you should have a good argument to back it
up.
40. Precautionary principle
Sometimes people have to persuade others to accept the risks that come
from their actions, such as for adopting a new technology like genetic
engineering or nanotechnology. If a decision you make involves other
people, you have the burden of proof to convince them to accept any
risks.
This is no easy task – while our actions often have an effect on others, we
don't all have the same opinion about what risks are worth taking.
41. Precautionary principle
People can sometimes demand certainty that there be zero risk, when
applying the precautionary principle.
This is a misrepresentation of the principle though, and logically it is
impossible, for there will always be some doubt, even if an idea seems
certain. The precautionary principle not be interpreted as being about
100% risk free, but about having a clear understanding of the risks and
benefits of a decision, and knowing when to proceed cautiously .
42. Video
Watch Video 6:
The precautionary
principle
43. Activity 6: Pick your argument
New technology is often viewed with caution until it becomes familiar.
Given the mix of potential risks and benefits science can provide, it’s
important that decisions are made using critical thinking.
Read the handout titled Activity 6: ‘Pick your argument’.
Discuss which arguments are valid and which are invalid.
44. Activity 7: Classroom Discussion
Discuss the following issues with your class.
1. How safe is safe? At what point does something become safe or
unsafe? If it turned out to be the case that GM food was safe and could
save many people from starvation, would it have been an evil act to
delay introducing it?
2. A lot of people claim we should delay action on climate change until
all the science is in and we have absolute proof. Some people say the
same about new technologies, such as genetic engineering, but think
we should act now on climate change without waiting for absolute
certainty. Can these two completely contradictory positions be equally
legitimate?
45. Activity 7: Classroom Discussion
3. If new technologies were developed by a massive philanthropic
organisation, rather than by multinational corporations, would this
affect the merits of the technology or not? Would any philanthropic
organisation be acceptable? What if the philanthropy came with – for
example – religious or political strings?
46. Activity 7: Classroom Discussion
4. Here are three questions we could ask when applying the
precautionary principle to a new technology:
• What are the benefits that the new technology could provide –
what are the risks and uncertainties associated with the
technology?
• What are the risks and uncertainties attached to any current ways
we have of realising the same benefits using existing technologies?
• Do these work? What would you suggest?
