UCAT Decision Making Definitions: Every Logical Word and Its Trap

At TheUKCATPeople, I am Dr Akash, and this is the shortest route to a higher Decision Making score that I know of. The logical words used in Decision Making have fixed meanings, those meanings are narrower than everyday English, and a large share of wrong answers are not reasoning failures at all. They are vocabulary failures. A student who treats "few" as though it means "some" will get a run of questions wrong while reasoning perfectly.

This page is the reference sheet: every logical word, what it allows in numbers, and the specific trap built on each one. It is worth learning to the point of recall, because unlike almost everything else in the UCAT, this part is finite and it is entirely within your control.

In the 2026 UCAT, Decision Making is 35 questions in 37 minutes, just over a minute per question, with a simple on-screen calculator and no negative marking (UCAT Consortium).

These definitions are used most heavily in syllogisms, and they interact with the notation method in the formal logic guide. For the section as a whole, start at the Decision Making complete guide.

Every UCAT logical word at a glance

Read down the third column before the second. The number range is what actually decides answers, and it is the part students never quite pin down.

The one picture that fixes most of these

Almost every definition error is a student placing a word in the wrong part of the same 0 to 100 per cent scale. Rather than learning the words in groups, learn where each one sits on one line, and the overlaps that cause the confusion become visible instead of abstract.

Three things the picture tells you that a list does not

• Few is a claim, some is not. Few asserts a minority. Some asserts only that at least two qualify and at least one does not, and is silent about proportion.
• Not all starts further left than some. One exception satisfies not all, whereas some requires more than one member on each side.
• Most and few cannot both describe the same subgroup, because their ranges do not touch. If a premise gives you most, any conclusion using few about that same group is No.
• All and none sit outside every other band. Most, some, many, few and not all all exclude 100%, so an "all" premise does not support any of them. That is the rule most students get backwards, and it has a section of its own below.

Absolute words: all, none, no, nothing, always, never

These are categorical, meaning they hold in every case with no exceptions. They are the strongest claims available and, usefully, the only ones you can safely rearrange, provided you rearrange them correctly.

• All, every, each and any behave identically. Whichever word appears, the claim is 100% with no exceptions.
• No and none are the same claim. "None of the A" and "no A" are interchangeable.
• Always and never describe occasions rather than members, so they attach to actions. Treat always as all and never as none and you will read them correctly.
• A single counterexample destroys any of these. That is what makes them worth attacking first when you are looking for a No.

Majority words: most, majority, few

These three are relative: they compare a subgroup to half. They are useful precisely because they are bounded, and they are dangerous because students round them to the nearest absolute word under time pressure.

• Most and majority both mean more than half but not all. They are interchangeable, and neither can be 100%: if it were, the correct word would be all.
• Few means less than half. It is a positive claim about a minority, not a vague word for "not many".
• Most and few are complementary but not exhaustive. Subtracting the majority from the whole leaves a minority, but the stimulus may also contain a subgroup it never mentions, so do not assume most plus few accounts for everyone.

Vague words: some, many, several, not all

This group makes the weakest claims, and weak claims are usually easier to support. From a mid-scale premise a conclusion using some is more often Yes than one using most, simply because there is less to prove. The exception is an "all" premise, which supports neither, because some and many both require at least one member outside the group.

• Some means more than one but less than all. Both halves matter: it needs at least two members in, and at least one out.
• Many is defined as similar to some. It does not imply a majority, and upgrading many to most is a standard trap.
• Several is not on the official list but appears in official practice questions, used as a synonym for some or many. Treat it as some.
• Not all is the weakest of the four. It needs only one exception, so a premise stating that a single member does not qualify is enough to support it.

Linking words: only, unless, either, both, neither, at least, at most

These do not describe proportions. They describe structure: which condition depends on which. They are the hardest of the definitions and, conveniently, the ones that formal logic notation handles best.

The notation for only, the only, only if and unless, with the contrapositive of each and worked five-statement sets, is in the formal logic notation guide.

The range test: does the premise fit inside the conclusion?

This is the skill the definitions exist to support, and it is the fastest single check I teach. Put the premise band and the conclusion band on the scale above, then ask one question: does the whole of the premise band sit inside the conclusion band? If it does, the conclusion is supported. If any part of the premise band falls outside, it is not.

That test is more reliable than the usual advice about "weakening" a claim, because it gets the top of the scale right, and the top of the scale is where most students go wrong.

• Upgrading is never safe. Some does not support most, most does not support all, and many does not support most.
• Downgrading is safe only in the middle of the scale. Most supports some and not all. All supports none of them, because every weaker word excludes 100%.
• Direction is a separate check. A conclusion can pass the range test and still be No because it swaps the two terms.
• Two rows carry a "more than one" condition. Few and not all can both be satisfied by a single member, while some cannot. Where a stimulus fixes the number at exactly one, "not all" is supported and "some" is not.

The same word in different question types

The definitions hold across the whole of Decision Making, but they bite differently depending on what the question is asking you to do. Knowing which job the word is doing saves you from checking the wrong thing.

Each of those has its own method guide: syllogisms, interpreting information, logical puzzles and strongest argument questions.

How to memorise these in three sittings

This list is short enough to know cold, and knowing it cold is worth more than another week of untimed practice. The protocol below is what I set for students who are losing marks on definitions rather than on reasoning.

1. Sitting one, about twenty minutes. Copy the scale figure out by hand from memory: the six positions from none through to all, with the number range under each. Check it against this page, correct it, then do it again. Handwriting the scale is what fixes the overlaps.
2. Sitting two, the next day, about fifteen minutes. Cover the middle column of the table at the top of this page and define each word aloud. Any word you fumble goes on a short list. Then define only the short list twice more.
3. Sitting three, two or three days later, about twenty minutes. Do not revise. Go straight into a timed set of syllogisms and mark it, then classify every error as either a definition error or a reasoning error. If fewer than a fifth are definition errors, this list is no longer your limiting factor and your revision should move on.

Spot the definition error

Eleven rapid statements, each built on a single misread word. Decide what is wrong before you read the verdict. These take about ten seconds each and they are the fastest diagnostic on this page.

• "All the seminars are recorded, so all the recordings are seminars." Wrong: the reversal trap on all. Plenty of other things get recorded.
• "Few of the students are graduates, so most of them are not." Correct, and worth noticing. Few caps the group below half, so the remainder is above half.
• "Some of the samples are contaminated, so some are not." Wrong, but only just. Some does guarantee at least one clean sample, because some means less than all. It does not guarantee more than one, and "some are not" needs more than one.
• "Not all the beds are occupied, so some are free." Wrong at the same boundary. A single free bed satisfies not all but not some.
• "Many of the tutors are examiners, so most are." Wrong: many carries no majority claim. This is the commonest upgrade in the section.
• "All the wards are staffed, so most of them are." Wrong, and it surprises people. Most means more than half but NOT ALL, so an "all" premise cannot support it.
• "Only nurses can administer the drug, so all nurses can." Wrong: the reversal trap on only. It tells you everyone who can administer the drug is a nurse, not that every nurse can.
• "Neither option was chosen, so not both were chosen." Correct, but weaker than the premise. Neither rules out each individually; not both still allows one.
• "At most three delegates attended, so three attended." Wrong: at most three includes two, one and zero.
• "The sample is either frozen or refrigerated, and it is frozen, so it is not refrigerated." Correct. Either in Decision Making excludes both, so establishing one settles the other.
• "No consultant is on the rota, so no one on the rota is a consultant." Correct. A "no" statement is the one type that reverses safely, because the negative does the work.

The seven confusion pairs, settled

• Few against some. Few claims a minority, under half. Some claims only that more than one qualifies and at least one does not. Few supports some wherever more than one member qualifies; some never supports few.
• Most against many. Most is a majority. Many is not, and is simply a larger-sounding some. Most supports many; many never supports most.
• Not all against none. Not all means at least one does not and at least one does. None means zero do. Not all is far weaker, and reading it as none is a common and costly slip.
• All against most and some. Most and some both exclude 100%, so an "all" premise supports neither. Only "at least one" survives a downgrade from all.
• Only against the only. Plain only reverses the sentence order, so only A are B means every B is an A. The only behaves like all and keeps the order.
• Either against both. Either means exactly one of the two. Both means the pair together. In Decision Making, either positively excludes both.
• Neither against not both. Neither rules out each of them individually. Not both still allows one of them, so it is the weaker claim.

Worked examples

Five sets in the exam format, each built to test the definitions rather than the reasoning. If you know the words, these are quick.

Worked example 1: the proportion words

Most of the tutors at a centre have taught for over five years. Few of the tutors hold a teaching qualification. All of the tutors have an enhanced DBS check.

For each statement, decide whether it follows from the information given:

1. Some tutors have taught for over five years.

Answer: Yes. Most means a majority, which is more than one and less than all, so it supports some. This is a safe downgrade.

2. Most tutors hold a teaching qualification.

Answer: No. Few caps that group below half, and most requires more than half. The ranges do not overlap.

3. Not all tutors have taught for over five years.

Answer: Yes. Most excludes all, so at least one tutor has not, which is exactly what not all claims.

4. Some tutors do not have an enhanced DBS check.

Answer: No. All of them do, so this directly contradicts the premise.

5. At least one tutor holds a teaching qualification.

Answer: Yes. Few means a small number under half, but it is a positive claim, so at least one does.

Statements 1 and 3 are both downgrades of the same premise and both Yes. Getting comfortable with how many valid conclusions a single "most" premise supports is worth real marks.

Worked example 2: only, unless and either

Only members may borrow from the library. A book is not renewed unless it is returned on time. Each returned book is either shelved or repaired.

For each statement, decide whether it follows from the information given:

1. Everyone who borrows from the library is a member.

Answer: Yes. Only marks the necessary condition, so borrowing guarantees membership. This is the premise read in the correct direction.

2. Every member borrows from the library.

Answer: No. The reversal trap on only. Membership permits borrowing, it does not require it.

3. A book that was not returned on time has not been renewed.

Answer: Yes. Unless makes on-time return the requirement for renewal, so failing it rules renewal out.

4. A returned book that has been repaired has not been shelved.

Answer: Yes. Either in Decision Making means exactly one of the two, so repaired excludes shelved.

5. A book returned on time is renewed.

Answer: No. On-time return is required for renewal, not sufficient for it. This reverses the condition.

Statements 3 and 5 are the two directions of the same premise, and only one of them follows. If you find yourself accepting both, you have read "unless" as though it worked both ways.

Worked example 3: the fussy boundaries

A committee has ten members. Exactly one member abstained from the vote. At least two members voted in favour. Neither of the two co-chairs voted against.

For each statement, decide whether it follows from the information given:

1. Not all members voted.

Answer: Yes. One member abstained, and a single exception is enough to satisfy not all.

2. Some members did not vote.

Answer: No. Some requires more than one, and exactly one member abstained. This is the boundary where not all holds and some does not.

3. At least one member voted in favour.

Answer: Yes. At least two voted in favour, and at least two entails at least one.

4. Exactly two members voted in favour.

Answer: No. At least two means two or more, so the figure is not fixed at two.

5. Both co-chairs voted in favour.

Answer: No. Neither voted against, and only one member abstained in total, so at least one co-chair did vote in favour. The other could be the single abstainer, so both voting in favour does not follow.

This set is deliberately pedantic, because so is the mark scheme. Statement 2 in particular separates students who know the definitions from students who know roughly what the words mean.

Worked example 4: absolute words and their reversals

All of the ward clerks have completed fire training. None of the ward clerks holds a clinical qualification. Every member of staff who holds a clinical qualification has completed fire training.

For each statement, decide whether it follows from the information given:

1. Everyone who has completed fire training is a ward clerk.

Answer: No. The reversal trap. Clinically qualified staff have completed it too, and the premise never limits fire training to clerks.

2. No one who holds a clinical qualification is a ward clerk.

Answer: Yes. A "no" premise reverses safely, because complete separation works in both directions.

3. Some ward clerks have not completed fire training.

Answer: No. All of them have, so this contradicts the premise directly.

4. Every member of staff has completed fire training.

Answer: No. Two groups are covered, ward clerks and the clinically qualified. Nothing is said about anyone else on the staff.

5. Someone who has not completed fire training does not hold a clinical qualification.

Answer: Yes. The contrapositive of the third premise: qualification guarantees training, so no training guarantees no qualification.

Statement 4 is the scope trap rather than a definition trap. Two "all" premises about two groups never combine into a claim about everybody.

Worked example 5: mixed strengths in one stimulus

Most of the practices in the region offer evening appointments. Few of the practices offer weekend appointments. Not all of the practices have on-site parking.

For each statement, decide whether it follows from the information given:

1. Some practices in the region offer evening appointments.

Answer: Yes. Most is a majority, which is more than one and less than all, so the downgrade to some is safe.

2. Most practices offer weekend appointments.

Answer: No. Few caps that group below half. Most requires more than half, and the two ranges cannot both hold.

3. At least one practice has on-site parking.

Answer: Yes. Not all means at least one does not and at least one does. Students who read not all as none mark this No, which is the trap the wording is built on.

4. All practices that offer weekend appointments also offer evening appointments.

Answer: No. Two separate proportions of the same population tell you nothing about the overlap between them.

5. Not all practices offer evening appointments.

Answer: Yes. Most excludes all, so at least one practice does not, which is exactly the not all claim.

Statement 4 is the overlap trap and it is worth dwelling on. Knowing what proportion of a group has property X and what proportion has property Y never tells you how the two properties are distributed across the same members.

Test yourself

Work these before you read the answers below the list. Retrieval beats rereading: if you can state each definition and its number range from memory, the words will stop costing you marks.

1. A premise states that few of the delegates are consultants. Does it follow that some of the delegates are consultants?

2. A premise states that many of the applicants hold a degree. Does it follow that most of them do?

3. What is the difference between "not all patients were seen" and "no patients were seen"?

4. "Only postgraduate students may use the study room." Does every postgraduate student use the study room?

5. A statement says each sample is either frozen or refrigerated. How would you disprove it?

6. What does "at most three" allow?

Answers

1. Yes in any realistic stimulus, with one caveat worth knowing. Few is a positive claim about a minority, so at least one delegate is a consultant. Strictly, some also needs more than one, and few can be satisfied by a single delegate, so the conclusion follows wherever more than one qualifies.

2. No. Many is defined as similar to some and carries no claim about a majority. This is an upgrade and is always No.

3. Not all means at least one was not seen and at least one was, anywhere from 1% to 99%. None means zero were seen. Not all is far weaker, and treating the two as equivalent is one of the commonest definition errors.

4. No. Plain only marks the necessary condition and reverses the English order: everyone using the room is a postgraduate, but postgraduates need not use it.

5. Find a sample that is both frozen and refrigerated, or one that is neither. In Decision Making, either means exactly one of the two, so both and neither are each enough to disprove it.

6. Three, two, one or none. The commonest slip is forgetting that at most includes zero.

Once the definitions are secure, the next gain is in how you apply them under time. Work through the syllogisms guide for the Venn method, the formal logic guide for conditional statements, and the 17 Decision Making tips for the section-level tactics. You can drill the words themselves on our free syllogism foundations trainer.

Key Takeaway: Learn where each word sits on one 0 to 100 per cent scale rather than as a list. None is zero and all is 100. Few is under half, most and majority are over half, and some and many sit anywhere between more than one and less than all while claiming nothing about proportion. Not all needs only a single exception, which is why it is weaker than some. Upgrading a claim is never safe, and downgrading is safe only in the middle of the scale: most supports some, but all supports neither most nor some, because both of those exclude 100%. Only, unless and either describe structure rather than proportion, so they are checked for direction instead.