Home/MDCAT/Logical Reasoning/Critical Thinking
Chapter 1 of 6 · Logical Reasoning
Critical Thinking
Critical thinking MCQs test assumption-finding, argument evaluation, and conclusion validity; identify the premise, the conclusion, and the gap between them before judging the answer.
Critical Thinking is a Logical Reasoning chapter on the official PMDC MDCAT 2026 syllabus, contributing roughly 2 MCQs to the 9-MCQ Logical Reasoning section. Mastering the core concepts below typically secures the full chapter weightage.
The structure of every critical-thinking item
Every UHS critical-thinking MCQ presents a short argument: one or two premises and a conclusion. Your job is to detect what the argument assumes, what would weaken it, what would strengthen it, or whether the conclusion actually follows. Before reading options, isolate three things on the question paper margin: P (premise), C (conclusion), and the unspoken bridge between them.
Worked example: spotting an assumption
"All medical students who study for six hours daily pass the UHS test. Ali studies for six hours daily, so Ali will pass." Premise: six-hour studiers pass. Conclusion: Ali will pass. The argument assumes (a) Ali is a medical student, and (b) the rule applies in his test cycle. Any option that questions either assumption weakens the argument; any option that confirms one strengthens it.
The four common question stems
- Strengthen: which fact, if true, makes the conclusion more likely?
- Weaken: which fact, if true, makes the conclusion less likely?
- Assumption: what must be true for the conclusion to hold?
- Inference: what conclusion is best supported by the premises?
Common logical fallacies tested
Recognising fallacies by name speeds up elimination.
- Hasty generalisation: drawing a broad conclusion from a single example.
- Post hoc ergo propter hoc: assuming that because B followed A, A caused B.
- Ad hominem: attacking the person rather than the argument.
- Circular reasoning: the conclusion is restated as a premise.
- False dilemma: presenting only two options when more exist.
The negation test for assumptions
To verify that an option is the necessary assumption, negate it and re-read the argument. If the negation breaks the conclusion, the option is the correct assumption. If the argument still stands after negation, the option is not the assumption.
Time discipline
Critical thinking items are slow. Cap each at 75 seconds. If you cannot map P, C, and bridge in 30 seconds, mark and move. RS Aggarwal's A Modern Approach to Verbal & Non-Verbal Reasoning contains 200 worked items in this format and is the standard practice source.
Key Concepts
- Argument structure
- Assumptions
- Strengthen/weaken
- Inference
- Logical flaws
Worked MCQs
Q1. Argument: 'Whenever the city installs more streetlights, crime drops. Therefore, brighter lighting deters criminals.' Which option, if true, most weakens this argument?
- A. Streetlights are expensive to install.
- B. The city also doubled police patrols in the same areas where lights were installed. ✓
- C. Crime rates fluctuate seasonally.
- D. Some criminals operate in daylight.
Explanation: If patrols doubled at the same time, the drop in crime may be due to patrols, not lighting — an alternative cause that breaks the inference.
Common trap: Common trap: cost (option A) is irrelevant to whether lighting deters crime; eliminate options that do not address the causal claim.
Q2. All doctors are graduates. Some graduates are researchers. Which conclusion validly follows?
- A. All doctors are researchers.
- B. Some doctors are researchers.
- C. No doctors are researchers.
- D. None of the above can be concluded. ✓
Explanation: From 'all doctors are graduates' and 'some graduates are researchers', we cannot identify whether the 'some' overlap includes doctors. No definite conclusion follows.
Frequently Asked Questions
Is critical thinking the same as logical deduction?
They overlap but differ. Deduction works on formal premises (all/some/none); critical thinking evaluates real-world arguments and looks for assumptions and fallacies.
How do I improve quickly?
Drill 10 strengthen/weaken questions per day from RS Aggarwal or Dogar's MDCAT LR section, and write down the assumption for each before checking the key.
Are these questions opinion-based?
No. Each item has a single defensible answer that follows from the stated premises. Personal opinions are irrelevant.
How many critical-thinking MCQs appear per paper?
1 to 2 per UHS paper, sometimes blended with cause-and-effect items.
How Critical Thinking Is Tested
MDCAT questions on Critical Thinking are a mix of recall (definitions, classifications), application (predict outcomes, interpret diagrams), and basic numerical/analytical reasoning. PMDC papers from 2020–2025 emphasized the concepts above; older UHS papers (2008–2019) tested them too, with slight variations in question framing.
Practice
Drill Critical Thinking and the rest of Logical Reasoning — free, no signup.
See the full MDCAT 2026 syllabus or browse all Logical Reasoning chapters.