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A philosophy interview at Oxford or Cambridge is the stuff of legend. The example Oxbridge Philosophy interviews you may have heard might be terrifying.

Have you heard about the person that proved the existence of God in their interview? Or the person that walked out of the room when the interviewer asked them what bravery was? Or the interview where the student set the interviewer’s desk chair on fire in an effort to prove objects exist outside of our mind? This is all a little hyperbolic, but Oxbridge philosophy interviews are still pretty scary things.

However, to disillusion some of the myths for you, we have here a rough transcript of three different questions you may get asked in an Oxbridge philosophy interview, written by myself and Jamie Slagel, a current Oxford undergraduate. We’ve commented on the interview throughout, explaining exactly what’s good about each student’s responses.

If you’d like to know more about Oxbridge philosophy interviews, take a look at our guide to preparing for Oxbridge philosophy interviews, or our reading lists for getting started with philosophy.

Question One: Thinking about ideas

Interviewer and student meet, introduce themselves, shake hands. 

Interviewer: So, how do we know this chair is blue?

This is quite common; Philosophy interviews often start with a broad general question, and then the interviewer will watch where the student takes it, and develop it.

Student: Well, we know the chair is blue because it fits the idea of blue we have grown accustomed to from observing many different blue objects. For example, I know that my top is also blue, and that this pen is blue, and I can see that there is something common in each of these objects, and that that common thing is blue-ness. 

Interviewer: But would you say the blue in your pen is the same as the blue in your top which is the same as the blue in this chair? 

This is also common in Philosophy interviews: the interviewer will ask you something they know not to be true, so that they can further press you on a point you have made.

Student: No, they are all different shades of blue. 

Interviewer: But then what is the underpinning thing that makes them all blue?

Student: Well, I have an idea of what constitutes something being blue. And it is clear that the chair, the pen and my top all satisfy this idea. Although they all form different types of blue, they clearly all come under the umbrella term of blue. 

Interviewer: Where did you get this idea of blue you suppose you have? 

Student: Well, through lots of instances of seeing blue. I read about Locke’s Theory of Abstract Ideas, where he talks about abstracting the quality blue from many particular instances of blue. We can then form an abstract general idea of blue, in which it contains all the different shades of blue.

This is good, as the student has linked in some of the reading they have done to the question, but it is not shoe-horned in, as it would have been if they had immediately jumped in with Locke’s Theory of Abstract Ideas. 

Interviewer: Interesting point. But what then would you say an abstract general idea is? 

Student: Well, I would say an abstract general idea is something that does not actually exist in the world, but something that exists in our minds – for example, the colour blue. Or the idea of a sphere – there is no abstract idea of a sphere in the world, but there are lots of particular instances of a sphere, such as in an apple or a tennis ball. 

Interviewer: Okay, so Locke also says in his Theory of Abstract Ideas that not only do abstract general ideas contain all the qualities of particular instances of that idea, but also none of these at the same time? 

Student: I’m sorry, I don’t think I really follow.

It is definitely better to admit not knowing something than to pretend you do. Also, remember the interviewer will obviously know a lot more about any philosophical theories than you do, so don’t be disheartened if they correct any points you make. I don’t think anyone properly understands Locke anyway. 

Interviewer: Let me clarify. So Locke says that an abstract general idea of something contains all the possible qualities that can belong to that idea when it occurs in the world, but also none of these at the same time. For example, the abstract general idea of an apple contains just the property of apple-ness, and none of its particulars, but also the property of being a Braeburn and a Granny Smith, as well as being round, bruised, perfect, crisp, soft, bitter, or sweet. 

Student: But isn’t that a contradiction? Surely nothing can be sweet and bitter at the same time?

Here the student is engaging with the interviewer’s new piece of information, which is a good skill to show.

Interviewer: Well, exactly, the famous example is of the triangle that must be isosceles, scalene and equilateral, whilst being none of these at all. But this all depends on how you define an idea. How do you define an idea?

The interviewer is taking the question off on a tangent here. This is very common, so they can see how you develop different concepts. 

Student: Well, I would say that an idea is something in my mind that reflects something I have seen in the external world. So I have an idea of that blue chair because I can see it using my sense of sight. 

Interviewer: So ideas form images of the external world? 

Student: Yes, I would say so, because when I am thinking about things, I see a reflection of what it looks like to me.

Interviewer: So do blind people have no ideas? 

Student: I would say a blind person can have ideas of sounds but not sights, in the same way that a deaf person could have ideas of sights but not sounds. 

Interviewer: Okay, so you’re saying that all our ideas are gained from the external world?

Here the interviewer is pushing the concept introduced by the student. This is a good thing, as it shows they are interested in the view she poses.

Student: Well, not all of them. Well, I don’t think we can form all of our ideas from the external world, as not everything we think about is in the external world, surely. For example, I can think about situations that cannot possibly occur in the external world, such as flying pigs, or unicorns.

It is okay that the student here is going back on their original view. You do not have to stick completely to everything you started saying; the interviewer wants to see you thinking and rethinking.

Interviewer: But can you not construct your idea of a flying pig or a unicorn from data your senses have given you? 

Student: Yes, I suppose you could, because you could imagine attaching a pair of wings to the body of a pig. 

Interviewer: Exactly. But what about other types of ideas, such as that of infinity? We have no idea of infinity in the external world. 

Student: But surely we could gain an idea of the infinite from looking at the world, by just imagining a road that goes on interminably. 

Interviewer: Ah, but there is no such road in the world. And you cannot gain such a road by sticking together different roads, like sticking a pair of wings to a pig, as all roads are finite so their sum will also be finite. Essentially the world is finite, so nothing infinite can surely be contained within it? 

Student: I see, but do we really have any idea of the infinite? Is it just an empty concept used in mathematics so that we can manipulate extreme cases of our systems? I can’t actually imagine anything going on infinitely, so do I truly actually have any idea of it? I suppose, if our ideas are strictly contained to what is in the world, I cannot know anything about the infinite.

Extending the Question:

Here the interviewer may introduce another question or further explore the concept of infinity. They may ask you something like, “How would you define infinity?” or “Are there are any real examples of infinity or zero?” 

Alternatively, the interviewer may redirect the question towards the discussion of ideas and ask you a more abstract question, such as “Where do ideas come from?” or “Are ideas subjective or objective?”. 

What is the Question Testing?

As with all philosophy interview questions, this question is testing your ability to think broadly and clearly about complicated, unanswerable topics. They are not expecting you to present a solid answer, because nobody can do that, but they are expecting you to weigh up different sides of the argument, and make a careful and considered overall judgement. 

Related Topics at University: 

Looking at the theory of ideas is a central part of studying philosophy, as ideas are vital for understanding human knowledge and how it functions. 

Question Two: Valid arguments

Interviewer: An argument is valid if it’s impossible for the premises to be true and the conclusion false. Can you tell me whether the following argument is valid or invalid?

“If I am happy, then I am not sad. I’m not happy. Therefore I’m sad.”

Student: Ok, so, I’d say this is valid.

Interviewer: Why?

Student: [pause] I guess because if I’m not happy then I must be sad.

Interviewer: Ok. Imagine someone who feels quite neutral. Do they feel happy or sad?

Student: Neither, I guess. [pause] Oh—so that means that just because someone isn’t happy, doesn’t mean they’re sad.

If you realise, following an interviewer’s prompt, that something you just said is wrong, then you should definitely explain how your viewpoint has changed and what caused it to change—the interviewer’s prompt is trying to get you to do just this.

Interviewer: Exactly. So, is the argument valid?

Student: Well, I guess there is a case when the premises are true and the conclusion is false. If I am happy, then I’m not sad, but it may be the case that I’m neutral, so I’m neither happy nor sad. Then the conclusion is false, but the premises are true.

Interviewer: Right. What if there are only two states of being, either happy or sad—there’s no neutral feeling—is the argument valid then?

Student: [pause] Well, then, if you’re not happy, you must be sad. So the argument is valid, because there’s never a case where you’re not happy but aren’t sad either.

Interviewer: Are you sure?

The interviewer may say this to ensure that you’re not guessing or to try and show you that you’re wrong—the best thing to do in such a case is to go through your reasoning.

Student:  Well, if I’m not happy, then I must be sad. Since I’m not happy, I must be sad.

Interviewer: Does that follow from the premises? The argument just mentions that if I’m not happy, then I’m sad.

Student: I suppose. The argument itself may not suggest that if I’m not happy, I must be sad—but if there are only two states of being, then there are only two situations—either I’m happy, or I’m sad. So, if I’m not happy, then I’m sad. When we talked about there only being two states of being, that’s an added premise: “Either I’m happy or I’m sad”. Then the argument is valid.

The interviewer has brought a new piece of information in but is asking a question in terms of the original outline. Here, you’ve given a good answer by explaining how this new information means that you’re correct.

Interviewer: Ok, good. Now we’ll take a look at another argument. “No one knows who I am. Only I know who I am. Therefore I am Batman.”

Student: Well, the premises don’t lead to the conclusion. I don’t really see how knowing who I am has anything to do with being Batman. So I’d say it’s invalid.

Interviewer: Do premises need to lead to the conclusion for valid arguments?

Student: [looks at definition of “validity” again] Oh, I suppose not. But it is possible for the premises to be true and the conclusion false. I mean, it might be the case that only I, Spiderman, know who I am, and no one knows who I/Spiderman is—but that doesn’t mean that I’m Batman. I am Spiderman.

The student has done the correct thing and has readjusted their answer based on the question and the interviewer’s prompt.

Interviewer: Can it be the case that I know who I am and no one knows who I am?

Student: Oh…no. Because I am someone. So if I know who I am, then it can’t be the case that no one knows who I am.

Interviewer: Exactly.

Student: Oh, wait… if we can’t have it be the case that both premises are right, then I guess it’s never possible for the premises to be true. So, it’s never possible for the premises to be true and the conclusion false. So, the argument is valid.

Interviewer: Fantastic. Now I’d like you to construct some arguments for me. Can you come up with an invalid argument where the premises are all true and the conclusion is true too?

Student: Ok, sure. Well, let’s take “the sky is blue” as the first premise. That’s true. And then as a second premise, “grass is green”. And then as a conclusion, we could have “I am happy”.

Interviewer: Is that an invalid argument?

Even though you may have given a correct answer, the interviewer might question you to ensure that you do understand the question and to prompt you to give your reasoning.

Student: Well, yeah. Because even if the sky is blue and the grass is green, it might be the case that I am sad. So, it’s invalid.

Interviewer: Right, exactly. But are the premises and conclusion true?

Student: Um… yes? [pause] Sorry, I’m not entirely certain what you mean.

If you don’t really understand the question asked, you should ask the interviewer for clarification.

Interviewer: Well, is it always true that the sky is blue or that you are happy?

Student: Oh, well I guess in that case they’re not always true. But we can easily imagine a scenario where they are all true – the argument would still be invalid.

Interviewer: Ok, sure. Consider the original definition of validity. Does this mean that it must be impossible for the premises to be true and the conclusion false in all scenarios we can imagine, or just in one?

Student: I mean, I guess if something is impossible, then it must be the case in any scenario we can imagine. So, if an argument is valid, then in all possible scenarios, it can’t be the case that the premises are true and the conclusion false. [pause] Well, I guess then my premises aren’t always true. They might be false in a possible scenario. Maybe I can give an example where all the premises and the conclusion are always true but the argument is invalid…

Interviewer: Yes, that’s a good idea. So, can you give an example of something that is always true?

It’s often a good idea to start with building blocks and work your way up to a full answer.

Student: “A bachelor is an unmarried man”. That’s always true, by definition.

Interviewer: Exactly. So can you formulate an argument then?

Student: Sure. “A bachelor is an unmarried man. 2 + 2 = 4. Therefore, the sky is the sky.”

Interviewer: Ok, so I think those are all true. But is it an invalid argument?

Student: Um. I think so. Because we can have it such that the first two definitions are correct but then that the sky is not the sky… oh wait, that makes no sense! Of course, if the conclusion is always true, then there’s no possible way the premises can be true and the conclusion false. So, that can’t be an invalid argument.

Interviewer: Exactly. So do you think you can find an invalid argument with premises and conclusion all true?

Student: Well, yes, my original argument. Because clearly a premise or conclusion can be true without always being true. Validity is really when there is no possible scenario where the premises are true and the conclusion is false. In the scenario that we are currently in, this interview, my original example about the sky, grass and sea includes only true sentences, but there are many possible scenarios where the premises could be true and the conclusion false. So, yes. I guess in a sense it depends on what you mean by ‘true’, but I take that to mean true in the possible scenario which we’re talking in. If it means in every possible scenario, then there can be no such invalid argument because if the conclusion is true in every possible scenario, then there’s no scenario in which it’s false and so the argument must be valid.

Further Hints

While some students may immediately grasp the concepts on offer, others will initially feel a little more confused. In this example the student makes a couple of natural errors but is quick to pick up on them and provide good answers. Further hints may include the interviewer asking whether or not two of the student’s positions are compatible, working through a few examples of basic arguments or getting the student to explain what the definition of validity is.

With regards to the last question, which is quite tricky, the interviewer may ask what it might mean for something to be true, or to consider other possible scenarios i.e. at night when the sky is not blue.

Extending the Question

Many students may jump to the answer a lot quicker, especially if they’ve had any experience with logic before. The interviewer may suggest other potential arguments, or they may ask some more technically difficult questions:

Can you construct a valid argument where its premises AND conclusion are all false? → you should take your time and build the argument up step by step. Show why each premise is false, then why the conclusion is false, and then why the argument as a whole is valid. E.g. “The sky is green. Everything that is green is an emerald. Therefore, the sky is an emerald.”

What other conditions would you say are necessary for a good argument beyond being valid? → This is a tough extension question. The initial answer should probably be that the premises are true, as the conclusion will follow on from this. One sophisticated answer may refer back to the definition of “happy”/”sad”/”mental state” and talk about the meanings of the words – saying that a good argument is one which is valid under any interpretation of the word given. This would also refer to the idea of “possible scenarios” mentioned in the argument construction towards the end of the question.

What the Question is Testing

The question is testing the skill of logic. Interviewers won’t expect any previous formal knowledge but will ask informal questions about the logical validity of arguments. They’re trying to get you to apply the definition of validity to arguments, show reasoning, and then to apply this to constructing your own argument. The final section is broader and asks you to consider some more difficult concepts about truth and validity.

Related Topics at University

Logic, but also truth and philosophy of language. Logic is studied by all students of philosophy during Prelims at Oxford, and can be studied beyond that.

Question Three: Theseus’ Ship

Interviewer: Imagine a ship which we will call Theseus’ Ship. One day, one of its planks becomes damaged, and so it’s replaced. Theseus’ Ship heads out once again, is damaged once again and another plank is replaced. This continues for the next three years until every plank on Theseus’ Ship has been replaced. Is it the same ship?

Student: Well, no. All of its planks are different. So, it’s clearly a different ship.

Interviewer: So we can say that at time A it’s definitely one ship, and at time B, it’s definitely a different ship. At what time between A and B does it become a different ship?

Student: When all the planks are changed.

Interviewer: So, imagine a ship where it has had all but one of the original planks removed. Is it Theseus’ Ship?

Student: Well, yes, I suppose. There’s still some of the original present.

Interviewer: So imagine that just one speck of dust from the original ship remains, does that mean this new ship is the same as the original ship?

Student: I guess so. But that seems a bit strange. I mean, to suggest that this new ship, which is physically so different to the old ship, is the same as the old ship, but isn’t the same ship as the ship at time B, with all its planks, even every speck of dust, replaced, seems to make no sense, because it looks more like the ship at time B than at time A. I’m less sure now, but I guess that can still work.

Thinking aloud is really good to show the interviewer that you’ve weighed up other considerations/ideas.

Interviewer: So what if there were a billion specks of dust making up that original boat? Does that mean we can have a billion original boats by simply building new ships and giving each a speck of dust?

Student: Um… I guess that is problematic. Because if we took two specs of dust from Theseus’ Ship and created two new ships that were the same as Theseus’ ship, called X and Y, then we could take a speck of dust from X and create some ship Z. But then, X would be the same ship as Theseus’ Ship but Z wouldn’t be. That doesn’t make any sense. [pause]. But then, I wouldn’t want to say that the boundary is on the 50% line, because that doesn’t make sense either–

Interviewer: Why wouldn’t that make sense?

Student: Well, imagine we said that our new creation is the same as Theseus’ ship as long as 50% of its contents are the same as Theseus’ ship. Then we can say that some ship, D, is the same as Theseus’ ship since only half its planks have been removed. But then we can say that ship E is the same as ship D if only 50% of D’s planks have been removed. But then ship D and ship E would be the same ship, and ship D would be Theseus’ ship but ship E, with only 25% of the planks from Theseus’ Ship, would not be Theseus’ Ship.

Interviewer: Right.

Student: [pause] So I guess that means that I can’t draw a line anywhere. So I’d say that any physical difference which occurs renders the ship a different ship.

Interviewer: But that means that if we only replace one damaged plank, it’s no longer Theseus’ Ship. Is that right?

Here the interviewer is questioning whether this position is really any good, and the best thing to do is to show why you understand their point but nevertheless believe in your own point.

Student: I guess it’s counter-intuitive, but the other position just leads to logical problems, so I think this is the best position. 

Interviewer: I’m not so sure. I think this position leads to logical problems too, and I think there’s a way of rendering the original position without logical problems. I mean, taking this position, no object ever actually remains. As soon as some atomic change occurs, the ship is no longer the same ship. If just a speck of dust is scraped off, the ship is a different ship. But, imagine that the ship is destroyed entirely by a storm, and every atom which comprises the original ship is scattered. We’re agreed that the ship no longer exists?

Student: Yes.

Interviewer: Now imagine that, by chance, 2000 years later, every atom of the original ship is reunited and by some highly unlikely chance, the atoms reform in the same way as the original ship. Napoleon claims that this is Napoleon’s ship. Is this the same as Theseus’ Ship?

Again the interviewer turns the position on its head to try to entangle you in some irresolvable problem – you need to try to give reasoned arguments as to why your position is right.

Student: Well, I wouldn’t say so… But I guess the position I took would be committed to saying that it is the same ship.

Interviewer: Exactly. 

Student: But I guess I’m not sure then. Both positions seem untenable.

Since the interviewer has pressed hard, it’s best to admit that you don’t feel like any position is any good now, if you can think of no alternative, rather than clinging on to a position you’ve agreed is wrong.

Interviewer: Well, why not take a view that suggests that ship A at time 1 and ship B at time 2 are the same if and only if they are physically continuous with one another? So, much like how you are familially continuous with all your ancestors, we can say that a person is your ancestor if they are your parent or a parent of one of your ancestors. Similarly, we can say that ship B is the same as Ship A if it is physically continuous with ship A, or with some ship which is itself physically continuous with ship A.

Student: But what would physically continuous mean here?

It’s good to ask intelligent questions clarifying the interviewer’s position/idea.

Interviewer: We can say that it means that there is some physical element of A present in B.

Student: That makes sense. However, doesn’t this just lead us to the earlier problem? I mean, that means that every single speck of dust from the ship is physically continuous with it. So there are millions of ships which are Theseus’ ship all of a sudden.

It’s really good to show that you can link new information with prior considerations, as done here.

Interviewer: That’s a good point, but I may adopt a 50% position, like earlier. So, A = B only if B is physically continuous with A, where each step of physical continuity requires that 50% of the original ship is retained. Do you think that such a position would suffer the same logical problem as earlier i.e. the problem that ship D is Theseus’ ship, ship D is ship E, but ship E is not Theseus’ Ship ?

Student: Well… If ship D had 50% of Theseus’ ships’ planks, and ship E has 50% of ship D’s planks, then we can say that they are all physically continuous with one another. They’re all the same. So, no, it doesn’t suffer from the same problem. That’s a good position, then, I guess.

Interviewer: Can you think of any problems for this position?

The interviewer will constantly test your ability to adapt to new pieces of knowledge – they want to understand how well you will learn when faced with new and challenging pieces of information.

Student: Oh, um… [pause]. I guess it’s not a logical problem, but it’s linked to what we just discussed. In that example, we said that Theseus’ Ship = Ship D = Ship E. But what if when Theseus’ Ship was sailing, a storm hit, and it split into 4 equal parts? Fix up one part with a load of other planks and call that Ship F, we would say that Ship F is not Theseus’ Ship.  However, in physical terms, it could be exactly the same as Ship E. Your account suggests then that E is but F isn’t the same as Theseus’ Ship even if E and F are qualitatively identical with one another. This seems particularly problematic. Again, we can’t draw a hard line as to when continuity does and does not seem to constitute identity.

Interviewer: Exactly.

Student: Even if we tried to draw a less strict line, like 30%, then this would just mean we could have three new ships which are all Theseus’ Ship, which doesn’t really seem to make any sense.

Interviewer: Well, what then makes Theseus’ Ship different to, say, the Titanic?

Student: I’m not sure, but I think we need to move away from any physical accounts. Maybe we could think about its purpose, or who uses it. Or maybe there is no such thing as Theseus’ Ship, it’s just a figment of our imagination.

Further Hints

You may find it difficult to come up with many of the arguments used in this model answer. The interviewer is likely to prompt you, by suggesting a scenario, as we saw above. They will provide an example and ask you to comment on what this means for our definition of identity. They may also ask you to consider what it is that makes two objects identical.

Extending the Question

This is quite a challenging example, but the interviewer may consider other positions such as those suggested at the end of the model answer – i.e. the position that a ship’s identity is defined by its function, by language, by people’s attitudes towards it, by who uses it and so forth. They may then consider problems for each of these positions, and comparisons of these to other previously discussed positions.

Another way of extending the question would be to contrast the identity of a ship to the identity of a human, and start to delve into what personal identity consists of.

What the Question is Testing

The question is testing your ability to tackle a philosophical paradox that isn’t in the slightest agreed upon to this day – the emphasis is on your reasoning and your ability to understand the different positions and their relative merits and difficulties. The question is also testing your mental agility, as you have to consider many different positions.

Related topics at university

This is related to metaphysics, identity and personal identity, all covered in the General Philosophy module studied during Prelims for all Philosophy students at Oxford. 


Hopefully, these example Oxbridge philosophy interviews have shown you that the interviews aren’t arcane or mysterious. They simply require you to think carefully and to react organically to new material.