Critical Thinking AS OCR

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Arguments, Reasons + Conclusions

  • Argument:
  • A piece of writing or speech that tries to persuade you to accept something
  • Conclusion:
  • The thing the argument is trying to persuade you to accept, this is backed up with reasons
  • Reasons:
  • The parts of the argument aiming to persuade you to accept the conclusion
  • Assertion:
  • A statement that isn't backed up by any reasons
  • An argument must have ONLY one conclusion and AT LEAST one reason
  • A difference of opinion is NOT an argument
  • Changing the order doesn't change the argument's structure 

e.g R1>R2>R3>C or R1>C>R2>R3

  • If asked to state something, must quote WHOLE thing (no ... or rephrasing)
  • Argument Indicators - help identify parts of the argument (conclusion, reason)
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Argument Indicators

  • They help identify parts of the argument (conclusion, reasons etc)
  • They don't always include them in exams!!
  • You can put them in yourself to see which parts are where
  • They can be used in other contexts as well
  • Reason Indicators: Because, since, due to, as, for etc.
  • Conclusion Indicators: Therefore, thus, so, consequently, should, which is why etc.

The Therefore Test:

  • Put the word "therefore" in front of a statement to see if it works as a conclusion
  • Then put the word "because" in front of the other statements to check the conclusion follows them as reasons
  • If it makes sense, you have identified them correctly
  • It can also be used to check if there are any misleading argument indicators in a text or none at all.
  • Therefore... because.... because
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Counter-Arguments and Counter-Assertions

  • Counter-arguments and counter-assertions disagree with the main conclusion
  • Showing why the counter-argument or counter-assertion is wrong can strengthen an argument's conclusion, this is called dismissing a counter-argument
  • Another reason for including them is to make it seem balanced and well thought out
  • They perform the same role
  • Counter-Arguments contain reasons, so are whole arguments
  • Counter-Assertions have no supporting reasons, so are just statements
  • To find one, look for the reason which doesn't support the author's conclusion

Also look for these words:

  • Despite this
  • Howeve
  • Although
  • It has been claimed
  • Contrary to this
  • Some people argue
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Simple Hypothetical Reasoning

  • Sometimes an argument will predict in a claim what might happen as a result of someting else
  • It's usually in the form of "If..... then...."
  • The then is not always included
  • Or the order may be reversed
  • Hypothetical reasoning can be used as a reason or the conclusion of an argument.

"If you buy a pet llama, then you will never run out of wool"

  • In the exam you may be asked to explain why something is hypothetical
  • Eg. "This is hypothetical reasoning because the conclusion refers to a consequencs (then..) that depends upon a conditional event (if....) in order to happen."
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  •  An unstated reason needed for the argument to make sense
  •  It must be necessary to the conclusion, and connects the reasons to the conclusion, without it the argument won't work
  • There can be more than one assumption
  • It doesn't mean an argument is weak if it relies on 

Argument: The weatherman said it's going to rain later on, so you should pack an umbrella

Assumption: You will want to protect yourself from the rain and an umbrella is the best way to do this

1) Identify the reasons and conclusion

2) Think about how they're connected - what are the missing steps joining them??

  • R1: It's the Police's duty to protect the public
  • R2: High-speed chases are the only way to catch some criminals
  •                   <--- A: significant proportion of criminals more dangerous than h-s chases
  • C: Therefore, high-speed chases are needed so the police can do their duty
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Assumptions 2

  • Be careful, clear and precise
  • This is too strong: All criminals are more dangerous than high-speed chases
  • This is too weak: A few criminals are more dangerous than high-speed chases
  • This isn't relevant: The police enjoy high-speed chases

Opposite test:

  • Check the assumptions are necessary
  • Insert the opposite of the assumptions and see if it still works
  • If it doesn't make sense with the opposite assumptions then it proves that the author has to make these assumptions for the argument to work
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Evidence and Examples


  • Used to support reasons
  • Results, proportions, percentages, graphs, quotes of opinions
  • Purpose: to support one of the reasons
  • Makes the argument more convincing - better argument
  • Can come from research, supports reasons by proving they're true
  • Research: Personal observation, statement, estimates, data from survey
  • Can be presented as statistics


  • They illustrate reasons with a description of a real situation where they're true
  • Usually only describe one situation-too specific to effectively support broad conclusion
  • Makes reasons more developed and convincing
  • Not used as a reason itself
  • can be used to illustrate evidence
  • They are NOT extra reasons- not essential, still works without them
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Evaluating Evidence

  • This means deciding if it's useful
  • Researchers need to survey a reasonable proportion (sample)
  • If a statement is about a large population and the sample is too small, it's called over-generalisation
  • Needs to be representative-people from different backgrounds, religions, ethnicities etc.
  • The methods used to gather evidence can affect how representative it is - where, when?
  • Statistics can be interpreted differently - misleading by using different types of average
  • Should be relevant - linked to and supports the reason
  • Can be interpreted in different ways to support the argument - there could be other explanations
  • There may be a more like interpretation of the evidence - doesn't support it the same
  • Evidence with many possible meaning is ambiguous (explanation)
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Providing Extra Reasons

  • You might have to provide extra reasons to support the conclusion in a given argument

1) Pick out the reasons already give (Don't repeat any!)

2) Identify the conclusion - It may have two or more different key points

3) make sure the reasons are relevant to the key points

  • DON'T rephrase a reason already there
  • DON'T make it irrelevant to the key points
  • DO make sure it supports the whole conclusion (strong reason)
  • DO combine it with another point to make it stronger, the two points must work together to support the whole conclusion
  • DO only write the reason, not examples or intermediate conclusions
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Do the Reasons Support the Conclusions?

  • Assess how strongly a conclusion is supported by the reasons
  • No need to say whether the argument is strong or weak overall, only need to pick out some strengths and weaknesses
  • Reasons MUST be relevant
  • Just because the argument has lots of reasons doesn't mean that the conclusion is well supported, it may contain lots of irrelevant and only a few relevant ones
  • To be relevant the reason must be about precisely the same thing
  • They can still be relevant if they're only linked to part of the conclusion - but the argument must contain reasons for the other part of the conclusion otherwise it's weakly supported
  • It should be consistent - If they cannot be true at the same time it's called inconsistent reasoning
  • Language also needs to be consistent
  • Conflation is when the person arguing uses two words as if they mean the same thing when they don't (may be subtle difference)
  • Weak reasons often rely on questionable assumptions - it is not something most people would agree with
  • Always discuss the example in the question - arguments etc. and give quotes
  • Should consider both strengths and weaknesses
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  • A claim is a statement that can be challenged (questioned)
  • An argument's reasons and conclusions are both claims
  • An event or outcome is plausible if it's like to happen- unlikely event = less plausible
  • A claim is plausible if it's reasonable (could be true)
  • Just because a claim is plausible doesn't mean it's definitely true

Judging how plausible a claim is:

  • You need to conclude that one effect is more likely than the other
  • It may only ask you how plausible a single claim is
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  • A claim is credible if it can be believed
  • Even if a claim is plausible it may not be creible
  • To help decide you can look at the credibilty of the source who made the claim
  • If the source is credible then their claims will be as well
  • Even a claim that is credible AND plausible can still be false

Judging the credibility of a source material:

  • Write about the credibility of the its writer/organisation - if they're not credible then their claim will be less credible too
  • You will either have to make a judgement on one person's credibilty or compare how credible two sides are
  • Bias
  • Experience
  • Consistency/Corroboration
  • Reputation
  • Ability to see or perceive
  • Vested interest
  • Expertise
  • Neutrality
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  • Bias only happens when there is an emotional link or belief
  • It effects how people see an issue

Bias may make people prejudiced for or against a certain view

  • Can be biased because of background or experiences
  • These opinions make people biased towardds one side of the argument

Can be caused by:

  • Religion
  • Past experience
  • Family/Friends
  • If someone is biased it decreases their credibility
  • Biased arguments often only put forwards one side of the debate
  • Check to see if there is any information left out which disagrees with their point - used facts selectively
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Vested Interest

  • Vested Interest can be caused by someone/organisation gaining something from it going their way e.g. power, money reputation
  • It can also be there if the argument going their way allows the to avoid something negative e.g. financial loss, damage to their reputation
  • It is similar to bias - a motive for one sided arguments
  • Likewise it can decrease the credibility of a source

But it doesn't automatically make them less credible:

  • If they have a lot to lose from lying, they have a vested interest in telling the truth
  • This increases the credibility of their claims
  • If their career or business depends heavily on their reputation, they will have a VE in telling the truth

Must be able to say how it affects credibility - What side? What gain/loss? More/less credible?

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  • Neutrality is the opposite of bias
  • A neutral witness isn't in favour of or against either side
  • They're not biased and have no vested interest - no motive to exaggerate or lie

Neutrality always increases credibility

  • Just because a souce is neutral doesn't mean it's the most credible source
  • Neutral sources are balanced or aren't linked to either side
  • Neutral sources can be manipulated or used selectively to put across a biased, one sided argument
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Experience and Expertise

Experience and expertise are NOT the same thing

  • Sources can have expertise, experience or a combination of both

Experience: knowledge gained from having done or encountered something before

Expertise: specialist skills and training that give someone knowledge that most people don't have

  • Experience and expertise both increase credibility - likely to know more than most people about their subject
  • Experience or expertise must be relevant - if it isn't it won't increase the credibility of any of their claims
  • Someone who has expertise or experience in onw field might not be qualified to comment on issue in a different field
  • They are often neutral and tend to give both sides of the argument but not always
  • Their claims aren't always the most credible - but it increases their credibility
  • Should check: relevant training, reputation, any vested interest
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Your reputation is the opinion people have of you

  • Positive reputation = increased credibility
  • Negative reputation = decreased credibility
  • Based on previous actions, or past actions of group members
  • Many people have a vested interest in retaining a positive reputation
  • Even if someone isn't an expert, a good reputation will make their view and argument more credible

Must be careful using it to judge credibility:

  • Just because someone has acted in one way in the past doesn't mean they can't change
  • When judging a group reputation, we're making a generalisation, there are always exceptions
  • Reputation isn't always  fair - based on rumours/2nd hand evidence?
  • Think about the relevance of the reputation
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Ability to See or Perceive

Someone who's witnessed an event has seen or perceived it

  • Perceive = experience of the senses - not just the eyes
  • Having access to relevant information can also affect someone's ability to see/perceive

Several Factors can reduce someone's ability to see/perceive:

  • They didn't observe the whole event
  • The conditions at the time reduced their ability to see/perceive
  • They were distracted by something
  • They were affected by drugs
  • They were under physical or emotional stress
  • They have a medical condition or disability which reduces ability to observe/recall
  • They've forgotten some details since the event
  • They didn't understand what was happening

Primary evidence is first-hand and direct

Secondary evidence is second-hand and less credible as it has been changed as it's retold - called hearsay. Rumours and gossip are both types of hearsay

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Corroboration and Consistency

Corroboration is when two different sources say the same thing (agree)

  • Increases credibility
  • Can still have their credibility affected by other criterion

Accounts are conflicting or inconsistent if they disagree with each other

  • This is the opposite of corroboration
  • Some sources agree on the main points but disagree on the details - the credibility will then depend on how important the details are and how many differences there are

Accounts are consistent if they don't conflict, but also don't corroborate

  • I all of the claims in a single piece of evidence can be true at the same time, it is consistent
  • A piece of evidence is inconsistent if it contains conflicting claims

Consistent accounts are always more credible than inconsistent ones

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Assessing Plausibility

Need to be able to assess the plausibility (reasonableness) of a claim

  • Assess means saying which factors make the claim seem more/less plausible and then deciding how plausible it is overall
  • Use information from the source and your own knowledge
  • The answer should end with a conclusion saying how plausible the claim is

Deciding which claim is the most plausible:

  • Look at both sides of the argument and say which side is most plausible and reasons why
  • Then decide which is the most plausible outcome based on these reasons
  • You can argue either way, but you MUST back it up with reasons
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Assessing Credibility

Deciding which source is most credible:

  • Use the credibilty criteria to judge their credibility
  • Don't use all of the credibiliy criteria at the same time - decide which are the most relevant for each source
  • Criteria can be used together to help decide
  • Increase = Good reputation, good ability to see/perceive, neutrality, corroboration, consistency, relevant experience/expertise
  • Decrease = Bad reputation, lack of ability to see/perceive, bias, vested interest, conflicy with other sources, lack of relevant expertise/experience
  • Some combinations give us a strong reason to believe a source:
  • The more criteria you have that increase credibility, the more credible the source is
  • Some combinations give us a strong reason to doubt a source:
  • The more criteria you have that decrease credibility, the less credible the source is
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Assessing Credibility

Making a desicion based on the relative credibility of two sides of an argument:

  • Assess each person/organisation's claim
  • Decide which credibility criteria to apply and how they affect the credibility
  • Keep the judgement based on comparing the credibility
  • Talk about the credibility of both sides
  • Decide what you think will happen due to their credibility - If the most credible source says something should happen, and the only one saying it shouldn't is not very credible, then it probably will happen

Sometime you need extra information to judge credibility properly:

  • Might be asked what extra info is needed to judge the credibility
  • The info will depend on the criteria you've used
  • E.g. You've said they have expertise - you need to know about qualifications
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