Critical Reasoning

Evidence + Assumption = Conclusion

Evidence - explicit stated support for conclusion
Assumption(s) - unstated support for conclusion
Conclusion - main point

Assumption Strategy:
1) Identify the conclusion
• sounds most important and general
• sounds like an opinion
• preceded by conclusion keywords (therefore, thus, so)
2) Identify the evidence
• sounds like factual info
• sounds like it is contributing to believability of something
• keywords (because, claimed, as)
• is always true (no need to question it)
3) Identify the assumption
• fills the gap between the evidence and the conclusion, a general rule that ties the two
• must be true, if the author didn't believe it, the conclusion would be invalid

Red flags in answer choices:
• extreme statements (keywords: only, never, always)
• opposite
• irrelevant (often irrelevant comparison)
• out of scope (introduces new information)

Stem based approach:
1) Identify the question type
2) Untangle stimulus (read the stimulus)
3) Predict an answer (before looking at the answer choices)
4) Match the prediction with an answer choice

Strengthen / Weaken:
Manipulate the assumption. Correct answer doesn't need to fully prove or disprove the conclusion, just strengthen or weaken it.
Denying an assumption invalidates the conclusion.
Strengthening argument must cause the conclusion to make sense.

Causation:
If X & Y happen at the same time and it is assumed that X causes Y, it could be argued that:
- the reverse is true, Y causes X
- something else caused Y, Z causes Y
- it is just a coincidence

Logical opposite of X is not X

Inference:
What must be true based on what was said in the statement.

Inference Strategy:
1) Logically link each sentence
2) Paraphrase the argument
3) Go through answer choices one by one (difficult to predict an answer)

Degrees of certainty:
- Must be true
- Must be false
- Could be true
Think of what is being asked! All true except - means that can be either 'must be false' or 'could be true'


Some - Most
- Some - at least one
- Most - more than half
Cannot be determine which is greater
Most + Some = Some

Common Wrong AC:
- extreme
- could be true (new info that wasn't mentioned in the stimulus)
- opposite

Formal Logic
X -> Y
not Y -> not X