What are LNAT assumption questions?
LNAT assumption questions ask you to identify something the author must believe to be true for their argument to hold – something they have not stated explicitly but have taken for granted. They are phrased as: “The author’s argument depends on the assumption that…”, “Which of the following is an assumption made in the passage?”, or “The argument above presupposes that…”
Assumption questions test a specific logical skill: the ability to identify the hidden premises that connect an author’s evidence to their conclusion. They are difficult because the assumption is by definition not stated in the text – you have to work out what must be true for the argument to make sense.
Understanding what an assumption is
The gap between evidence and conclusion
Every argument has a structure: evidence leads to a conclusion. An assumption is the unstated belief that bridges them. If the evidence is “students who practice more score higher” and the conclusion is “you should do more practice papers”, the assumption might be “you want to score higher” – something the author takes for granted without saying.
Identifying assumptions requires you to look at what the argument leaves out. What would someone need to believe for this argument to work? What is the author assuming about the world, about the reader, or about the relationship between their evidence and conclusion?
Assumptions must be necessary, not just plausible
A common mistake is identifying something that is consistent with the argument rather than something the argument depends on. The correct assumption must be one that, if it were false, would cause the argument to collapse. Ask yourself: “If this assumption were not true, would the argument still work?” If yes, it is probably not the correct answer.
The technique for answering assumption questions
Step 1: Identify the conclusion and the evidence
Before looking at the answer options, identify exactly what the author is concluding and what evidence they are using to support it. Write it out if you find it helpful: “The author concludes X because Y.” This gives you the two endpoints of the argument and makes the gap between them visible.
Step 2: Ask what must be true for Y to lead to X
What unstated belief connects the evidence to the conclusion? What is the author taking for granted about the relationship between them? This is your assumption. It is often something so obvious that the author did not think to state it – but that is exactly what makes assumption questions difficult.
Step 3: Apply the negation test
This is the most reliable technique for assumption questions. For each answer option, negate it – make it false – and ask whether the argument would fall apart. If negating the answer destroys the argument, it is the assumption. If the argument survives even if the answer is false, it is not the assumption.
Example: The argument is “This policy has worked in three European countries, so it will work here.” One answer option is “The conditions in this country are similar to those in the European countries.” Negate this: “The conditions are not similar.” Does the argument collapse? Yes – if the conditions are completely different, the evidence from European countries tells you nothing. This is the assumption.
Step 4: Watch out for over-specific answers
Wrong answers in assumption questions often introduce specific details that are not in the original argument. The assumption needs to be the minimal belief required to connect evidence and conclusion – not a broader claim about the world, not a specific empirical fact, and not a value judgment the author has not made.
Common types of assumptions in LNAT passages
Certain types of assumptions come up repeatedly in the LNAT. Comparative assumptions bridge evidence from one context to another (“what worked there will work here”). Causal assumptions link correlation to causation (“X caused Y” rather than “X occurred alongside Y”). Population assumptions generalise from a sample to a whole group. Recognising these common types helps you identify assumptions more quickly under time pressure.
Build the skill through practice
Assumption questions become significantly easier with practice because you develop an instinct for the kinds of logical gaps that appear most often. Work through our free LNAT practice paper and pay particular attention to assumption questions in your review sessions. Our full-length LNAT practice tests give you the volume of practice needed to make this technique reliable under exam conditions.
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