Watson Glaser Deduction — How to Apply Strict Logic
Master the Watson Glaser Deduction section. Learn the strict formal logic rules, common traps, and step-by-step strategies to answer Follows / Does Not Follow.
What the Deduction Section Tests
The Watson Glaser Deduction section presents you with a short set of premises — statements you must accept as true — followed by a conclusion. Your job is simple in theory: decide whether the conclusion Follows or Does Not Follow strictly and necessarily from the premises.
This is not a general-knowledge test. It is not asking whether the conclusion is true in the real world. It is asking whether, given only the information in the premises, the conclusion is logically required. If you can construct even one scenario where the premises are true but the conclusion is false, the answer is Does Not Follow.
The section typically contains 5 items in the standard Watson Glaser format, and it is consistently the section where candidates make the most errors. Why? Because human brains are wired to use prior knowledge. Formal deductive logic demands you switch that wiring off.
For a full overview of all five sections of the test, see the Watson Glaser Critical Thinking Test — Complete Guide 2026. If you want to practise inference questions alongside deduction, visit Watson Glaser Inference — How to Master the Hardest Section.
Follows vs Does Not Follow — The Core Distinction
The Watson Glaser scoring guide defines the two answer choices precisely:
- Follows — The conclusion follows beyond reasonable doubt from the premises, using only the information provided. No additional assumptions are needed.
- Does Not Follow — The conclusion requires information not supplied in the premises, or is contradicted by the premises, or is merely probable but not certain.
Notice that probable is not enough. A conclusion that is likely to be true, plausible, or sensible in the real world still receives Does Not Follow if it is not necessarily true given the premises. This is the trap that costs most candidates marks.
Test yourself on real questions at the Watson Glaser Practice Test 2026 after working through the examples below.
The Four Statement Types and How to Reason Through Each
"All A are B" means every single member of group A belongs to group B — no exceptions. From this you can safely conclude that any specific member of A is also B. You cannot conclude that all B are A (that would be the converse fallacy). Example: "All lawyers passed the bar exam. Sarah is a lawyer." → "Sarah passed the bar exam" Follows. → "Everyone who passed the bar exam is a lawyer" Does Not Follow.
"Some A are B" tells you only that at least one member of A is also B. You cannot conclude anything about the rest of A, nor can you conclude that any specific A you are given is necessarily B. This is the most dangerous type — candidates routinely over-read "some" as "most" or assume it transfers to a named individual. Stick strictly to what the word "some" logically permits.
"No A are B" means zero overlap between the two groups — ever. From this you can always validly reverse direction: if no A are B, then no B are A. This is the one universal negative where the converse holds. You can also conclude that any specific A is not B and any specific B is not A. Do not confuse this with "Some A are not B", which is a much weaker statement.
"If P then Q" means whenever P is true, Q must be true. Two valid moves: (1) Modus Ponens — P is true, therefore Q is true. (2) Modus Tollens — Q is false, therefore P is false. Two invalid moves (classic traps): Affirming the consequent — Q is true, therefore P is true (wrong). Denying the antecedent — P is false, therefore Q is false (wrong). These two invalid moves appear frequently in Watson Glaser Deduction items.
Worked Examples and Common Errors
Example 1 — The Real-World Knowledge Trap
Premises: All members of the senior leadership team have completed the compliance training. James has not completed the compliance training.
Conclusion: James is not a member of the senior leadership team.
Answer: Follows. This is a valid Modus Tollens: if all SLT members completed training and James has not, James cannot be in the SLT. Notice this works purely from the premises — no outside knowledge is needed or used.
Example 2 — The "Some" Trap
Premises: Some project managers in the company hold a PMP certification. Alex is a project manager in the company.
Conclusion: Alex holds a PMP certification.
Answer: Does Not Follow. "Some" project managers hold PMP — not all. Alex could be one of those who does not. The premises give no specific information about Alex's certification status. Candidates who know that PMP is common among experienced PMs may be tempted to mark Follows — that is real-world knowledge contaminating the logic.
Example 3 — The Converse Fallacy
Premises: No candidates who scored below 70 were offered a position. Miranda was offered a position.
Conclusion: Miranda scored 70 or above.
Answer: Follows. "No below-70 candidates were offered" means all offered candidates scored 70+. Miranda was offered, so she scored 70+. This is a valid application of the universal negative conversion.
Example 4 — If-Then Affirming the Consequent (Trap)
Premises: If an employee passes the probation review, they receive a permanent contract. Chen received a permanent contract.
Conclusion: Chen passed the probation review.
Answer: Does Not Follow. The premises say passing the review leads to a permanent contract — but they do not say a permanent contract can only come from passing the review. Chen may have received it through another route. This is the affirming-the-consequent fallacy. Candidates find this difficult because in most workplaces the scenario seems obvious. Ignore what you know about workplaces.
For tips on approaching the test as a whole, including how to manage time across all five sections, see Watson Glaser Test: 7 Tips to Know to Pass Your Assessment.
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About the Author
Educational Psychologist & Academic Test Preparation Expert
Columbia University Teachers CollegeDr. Lisa Patel holds a Doctorate in Education from Columbia University Teachers College and has spent 17 years researching standardized test design and academic assessment. She has developed preparation programs for SAT, ACT, GRE, LSAT, UCAT, and numerous professional licensing exams, helping students of all backgrounds achieve their target scores.