Critical thinking

Adam introduces this section on critical thinking

  • Video transcript

    Adam: Welcome to this section on critical thinking. Critical thinking is a key university skill, but many students find themselves confused about what it actually is. In these pages, you'll find out what critical thinking means. You'll see some examples, and you'll have a chance to practise the skill. Over the academic year we also hold workshops on critical thinking, so keep an eye out for these.
    Remember, we're here to help you.

Critical thinking is a key skill for university and students can find the concept hard to grasp. However, it is something that you do already; when you choose how to spend your time, which news sources to listen to, and which products to buy. At university, you need to apply this analytical thinking to what you read, hear and write. Additionally, you must make sure to demonstrate that you have done so in your assessments.

Carlee and Rodrigo talk about their understanding of critical thinking

  • Video transcript

    Carlee: I think you hear critical thinking and it's a buzzword. It's something that everyone wants you to know how to do. And tells you it's so important to have to master that it can put a lot of pressure and you're like, what even is critical thinking? And I was exactly the same. I was like, 'Oh, well, you know, I'm being critical.' Like how I translated critical, I was just kind of being negative and like nit picking out like the flaws of things. And it wasn't until, you know, I got some marks back and some feedback and they're like that's not necessarily what critical thought is. It's kind of if you were to look at something and just say, 'How can I break this down into smaller pieces? What's helpful about this? What's not helpful about this? What's the advantages? What's the disadvantages?' And just kind of looking at something in both ways, not just your own perspective - that can kind of help you look at something and say, 'Oh, now I'm being critical about it.'

    Rodrigo: Right now I'm writing my essays and when I receive some feedback, I can see completely the difference. It's interesting how at the beginning of my first year I got like two forties and a couple of fifties as well. And I was like, why? Why is this happening? And right now I'm getting like my sixties and my seventies, and I can see a difference. I can definitely see a difference. My essays are more structured. I have more critical thinking like it's supposed to, like my uni wants to and yes, definitely, I can look at something and I'm like, is this really like this, what's the other point? What are the other arguments? Is this person who's talking, is she or he or they biased? Are they biased? So yes, definitely 100%. It's helped me grow and think critically. Yeah, for sure.

We also run workshops on academic skills throughout the year.
Find out about academic skills workshops and other support.
Don't expect to become an instant expert in critical thinking. Just as critical thinking itself is a process, becoming a critical thinker is a process.

For a free introductory critical thinking course, go to Future Learn.


What is critical thinking?

Imagine that someone tells you, “You’re going to need an umbrella.”

You have two options. You could take this information at face value and grab an umbrella. Alternatively, before deciding to do anything, you could think about the statement and ask yourself some questions.

Who said this? Was it a friend, a weather forecaster, a young child?

What are they basing their information on? Are they looking at the clouds, at scientific data, at cows lying in a field?

What are the implications of taking an umbrella? Will you need it straight away? Will you be able to carry it? Could you use something else instead?

What are the assumptions they are making? That dark clouds always produce rain? That people don’t like getting wet? That you are going outside?

With such a simple statement, it is likely that these questions are so automatic and take such little effort that you barely notice yourself asking them.

You need to use the same process in your academic studies. When you come across information, you can take it at face value and accept it as true, or you can step back and ask some questions. The difference is that the information you meet at university is new, more complex and less concrete. Therefore, the process of asking these questions takes more time and needs to be done consciously and deliberately, rather than automatically. This is critical thinking.

The word ‘critical’ often confuses students. Critical thinking does not mean that you need to always find fault with everything. It means that you analyse and evaluate arguments before deciding if you agree with them. Each argument may have some strong points and some weaker ones. Identifying both is important, as is understanding why you think they are strong or weak.

Difference between critical and descriptive writing

At Sussex, the academic sources you read and the assessments you need to produce often involve critical writing. This means that the writer has analysed data and sources and that they have thought deeply about a subject and come up with an opinion, based on reliable evidence.

Writing cannot be 100% critical, because to have an opinion on a topic, you must first describe what that topic is. However, often students lose marks because their writing is weighted too heavily towards descriptions of processes, concepts and other writers' opinions, rather than critical analysis of them. High marks in written assignments usually require more critical than descriptive writing.

  • Example of good critical writing

    Following from an understanding that Japanese feminist consciousness was concomitant with the emergence of modern Japan as an imperial nation, we should ask how Japanese feminism has been shaped and constituted by Japanese imperialism. If the very production of modern Japanese subjects has been entangled with Japanese imperialism, which in turn was a response to western imperialism, then we can understand Japanese feminism as the product and outcome of a hybrid modernity forged within a global history of competing racialized national-imperialisms. Indeed, the racialized dimensions of Japanese national-imperialism as it relates to Japanese feminism has been undertheorized.

    The words in bold are the description of the ideas that the writer is analysing.

    The words in italics show the writer critically thinking. In both sections, she is asking about the implications of the original ideas – what results if we take the ideas in bold as true? In the final sentence, she goes even wider and points out the lack of discussion of these implications.

    Note the structures that she uses to signpost critical thinking:
    - Following from [description], we should ask [critical analysis].
    - If [description], then [critical analysis].

    There are many other structures that lead from descriptive writing to critical writing. Look out for them because they help the reader – often you, or your tutor – identify where the writer brings in their own analysis.

    This would be a more descriptive alternative of the paragraph:

    It can be understood that Japanese feminist consciousness was concomitant with the emergence of modern Japan as an imperial nation. The very production of modern Japanese subjects has been entangled with Japanese imperialism, which in turn was a response to western imperialism.

    It’s drier, more factual and less interpretive. And much shorter!


    This example text was taken from:
    SHIGEMATSU, S. (2018). Rethinking Japanese Feminism and the Lessons of Ūman Ribu: Toward a Praxis of Critical Transnational Feminism. In J. C. Bullock, A. Kano, & J. Welker (Eds.), Rethinking Japanese Feminisms (pp. 205–229). University of Hawai’i Press.

Critically evaluating sources

You are expected to do a lot of research while at university. The books, journal articles and websites recommended on your reading lists have already been evaluated for their quality by your lecturers. When you are asked to find your own information, it’s important to take a critical approach. This starts with looking at the source itself, even before you read the text.

There is a significant difference between an article on "diets which may prevent cancer" published in a popular culture magazine, and one that is published in the Nutrition Research journal. For your work to meet assessment criteria at university level, you need to be able to base it on with acceptable sources which you have evaluated for credibility, reliability and impartiality.

Evaluating academic texts

The journals available through Library Search and your Subject Guides have gone through a rigorous vetting process, known as peer review. Peer review is a process whereby an article submitted to an academic journal is vetted by several experts in that field. The reviewer decides if the article should be published and may make suggestions for changes before publishing. Peer review is a rigorous vetting process. Consequently, peer-reviewed articles are held in higher regard than those which aren't. You can usually rely on these sources.

Open access publishing

If you are searching on Google Scholar or similar search engines and find a scholarly article you can freely access, this article is probably an open access article. The rise of open access publishing has changed the ways scholars share and use journal articles. You need to be extra vigilant when evaluating what appear initially to be scholarly journals.

The growth of open access publishing has resulted in an increase of predatory or vanity publishing. Opportunistic publishing houses publish content in exchange for publication fees, paid for by the authors. These predatory publishers don’t provide any of the editorial and publishing services associated with legitimate academic journals, such as a peer-review process. As a result, unreliable, unvetted publications are published and circulated online. Because of this lack of transparency, you need to be careful with texts from such sources and evaluate them yourselves.

If you have found an open access journal article and want to verify the authenticity as a reputable journal, you can check the name on the Directory of Open Access Journals (DOAJ).

Evaluating web pages

Anyone can put anything on the internet. It contains a large number of resources that are inaccurate or incorrect. Although some sites do not intend to misinform their readers, others are designed to mislead and so it is important to critically evaluate what you are reading. 

Use the CRAAP method to evaluate a web page:


Have I thought about this?


When was the information published, posted or updated?

Is the information relevant to the present day?

Does your topic require current information or are older sources acceptable?


Does the information relate to your topic or answer your question?

Who is the target audience?

Is the information aimed at a university level?


Who is the author?

What is the source?

What is the author’s or source’s credentials?

Are they qualified to write on this topic?


Is the information supported by evidence and references?

Is there any bias?

Has the text been peer-reviewed?

If it is a website, what is the URL?
(Some reliable URL’s end in .org, .gov, .edu,

Is a variety of views provided?


What is the purpose of the information? To inform/ persuade/sell/entertain?

What is the main aim of the organisation providing the information?

How does the author benefit from people reading the text?

You won’t ever find a flawlessly unbiased and reliable source of information. Critical evaluation means showing an awareness of a source’s strengths and weaknesses and choosing sources that have many strengths to back up your argument.

Evaluating news sources

If a news article seems too good to be true, or too sensationalist to be correct, it usually is. If you are unsure whether a news source is genuine, refer to the list below. Alternatively, see the International Federation of Library Association's How to Spot Fake News infographic.

Five factors to consider when evaluating a source:

  • Fact check. Use fact-checking websites such as to check the credibility of citations and quotes, and for images 
  • Verify the URL. Look carefully at the URL address. Fake sites often have urls that are extremely similar to well-known respected news outlets, but with a slight variation. For example, a fake news site modelled on was added to the internet with the URL
  • Vet the source. Is the source who they say they are? Are they vetted and verified? For example, if the information is coming from Twitter, the account holder will be independently verified if their profile includes a blue checkmark
  • Loaded language. Is the headline of the piece phrased in a way that is sensationalist or highly emotional? This is often a manipulative method referred to as loaded language and can be a form of clickbait, enticing the reader to click on the news story
  • Adverts. A high proportion of adverts on an article platform or news site can often be a sign of a platform primarily driven by pay-per-clicks, and not by journalistic integrity.

Five tools to help detect misinformation:

  • Wayback machine. Search for websites that have since been taken off the internet
  • Snopes. Hoax checker
  • Quote Investigator. Quote checker
  • TinEye and Google Reverse Image Search. Verify images for authenticity; you can search by uploading image files
  • Politifact. Political facts checker.


A valid source for one discipline may not be valid for another. Always consult with your tutor if you are unsure.

Identifying and evaluating arguments

'Good critical thinking includes recognising good arguments even when we disagree with them, and poor arguments even when these support our own point of view.'
Cottrell, S. (2017) Critical Thinking Skills, Third Edition, London, Palgrave, p33

This section is the key to critical thinking. If you are able to follow the argument in a source, and determine its strengths and weaknesses, then you are thinking critically.


Amelia and Georgia talk about developing their critical thinking

  • Video transcript

    Amelia: The critical part I brought to it is like, okay, so this is what I know and this is the knowledge I have. And to first understand before I read something or watch something or see something, it's like, this is what they're trying to teach me. And then having to like get from this point, okay, this is what I know and this is what I'm trying to gain and choosing a path to that is interesting. And it's interesting the whole way through. And when I meet something I don't quite easily understand, it's not like, okay, I'm done. It's like, okay, what are the questions I can ask myself in order to move past this, in order to continue in my understanding.

    Georgia: When it came to writing essays, critical thinking is something that I'm assessed quite a bit on and is a very crucial aspect, especially if you want to reach kind of the higher levels, higher grades. And I think at first, it was something that was very unnatural to me and was quite clunky and was sort of just I knew I had to do it. So I had a very basic critical evaluation and then it developed through writing more essays and through just thinking critically in my studies, and it became a lot more natural in how I put it into my essays and how it flowed. So I think it has definitely developed through all those different things.

Identifying arguments and reasons

Before you can evaluate an argument, you must be able to find it. This can be tricky, since lines of reasoning are usually spread throughout a whole text, as the writer slowly builds up their position, layering point after point backed up with evidence, and builds to a final conclusion. Reading abstracts and introductions is very useful to get an overview of an article or book and a summary of the argument that a writer is going to make. Always read them so that you know the general direction of a writer’s argument.

The conclusion is often indicated by signposting phrases such as so, therefore, thus, then, as a result, as a consequence, and for this reason. Generally, writers make their conclusions clear because they want their audience to see and understand them.

  • Sustainability is being embedded into the curriculum of several schools at the University of Sussex. As a consequence, more students are learning practical methods of living sustainably for the future.

In the above example, the section after as a consequence is the writer’s conclusion.

Once you have found the conclusion, you also need to find the reasons. Phrases that demonstrate these are more varied, but some common ones are because (of), since, as, the reason being, according to, and considering. Sometimes, such as in the above example, the reasons are not signposted, but simply put before the conclusion.

  • Since British students learn to communicate in English classes, and considering that coding is a language which contains many elements of English, then the fundamentals of computational language should be taught to British students in their English classes.

In this example, there are two reasons given for the conclusion. One after since, and one after considering that. The conclusion is signposted with then.



Read the following passage and identify the conclusion and the reasons that the writer makes. The video below gives the answer to this activity.

Some areas of the curriculum are well suited to particular activities. In language-linked and social studies courses, group writing projects offer more benefits to the student than simple improvements in writing skills. The negotiation required by group work encourages semantic webbing, gives practice in the evaluation and organization of gathered information, and offers reflection on the development of knowledge (Andrews, 1992). The group can serve as a respectfully critical audience for individual writing as well, honing the novice writer's presentation style with an immediacy and absence of threat that is less available in traditional assignments. The feedback of peers in the negotiation of the final product helps students gain a sense of authority over their own writing, in turn leading to a greater motivation to write (Chan 1988).

S. Marie A. Cooper. (2002). Classroom Choices for Enabling Peer Learning. Theory Into Practice, 41(1), 53–57.


Answer (video)

  • Video transcript

    So in this passage it is the first sentence, which is the writer's conclusion or the writer's main position. They say that some areas of the curriculum are well suited to particular activities and the rest of the paragraph gives examples and information about the particular activities. In the second sentence, it focuses on language linked and social study courses and talks about group writing projects.

    So this is a detail or an example of a particular activity. Then we have different reasons for this, here, all the way to the end of the sentence. There are different reasons for the particular well suitedness of the activities, and you can also see that no examples are given of poor suitedness to the particular activities. In the middle of the passage there is another sub conclusion, which is that the group can serve as respectively critical audience for individual writing as well. And the rest of this sentence explains this further and gives reason. The last sentence is quite interesting because there are two sub conclusions in it. The first sub conclusion is that students gain a sense of authority over their writing, and the beginning of the sentence gives a reason for this.

    But then, students gaining a sense of authority over their writing becomes the reason for the final sub conclusion, which is a greater motivation to write. You can see the language here ‘in turn leading to’, highlighting that the previous language, the previous part of the sentence is now turning into a reason. So you have three sub conclusions here, but all of the sub conclusions serve the greater conclusion which is at the beginning of the paragraph, which is that some areas of the curriculum are well suited to particular activities.


A conclusion that a writer reaches in one paragraph can become a reason for another conclusion in a following paragraph. For example, if one paragraph argues that dairy products are unhealthy, the next paragraph might use this as a reason why dairy products should be banned from school cafeterias.  

Implicit assumptions

Writers may base their conclusions and reasons on assumptions. These can be basic, general, or cultural and they can be very hard to spot. Use your critical thinking to keep an eye out for these assumptions and decide if and how they affect the conclusion.

  • Employers need to ensure that their employees are kept safe so that the costs of paying damages to injured workers do not become unfeasible.

An implicit assumption in this example is that the fundemental goal of businesses is to make as much money as possible. This might be a very pervasive mindset in capitalist society, but is it always true? It may be that the writer has designed an argument based on an assumption that you don’t agree with.

From the first assumption come others, such as:

  1. Employers always want to keep costs down
  2. Keeping employees safe is only important to employers because they can save money
  3. The costs of paying damages to injured workers can become unfeasible
  4. Injured workers demand to be paid damages
  5. It is the role of employers to keep their employees safe

Once you have identified the underlying assumptions made by a writer, you can then decide if you agree with them or not, and explore the evidence for them.


Sara and Reuben give advice on critical thinking

  • Video transcript

    Sara: So I did A-levels and we didn't do a lot of critical thinking. It was mostly just rote learning and you would kind of read and paraphrase it and then write it back in the exams. So I think, my first few assignments, that's what I did. And the feedback that I got was, well, yes, you've said this, but you haven't evaluated it, you haven't applied any critical thinking. And then I reached out for more support because this was something that I knew was important, not only for that time, but then later on for my dissertation as well. And when I reached out, they directed me to Skills Hub. They gave me their own advice, and it really helped me to understand what critical thinking is so that I could implement it.

    Reuben: I think it's a lot about critical thinking, and I feel like that's something that I'm really interested in, in developing, and I feel like I've got a really good strength in it on some level. But also I think I've learned a lot of how to really think about the other side. And within all your essays, you're going to have to include the other side and think critically about why this could, not just like your opinion is the only one. To make your opinions stronger, you really have to understand the whole picture. And that's something that really we had quite a few weeks on that with Sue. So yeah. And the Skill Hub does go through that. So just keep coming back to things because there's many angles to it and you just slowly build up more ways of doing it because it can be quite subtle. Yes, quite subtle ways to do it. And then quiet like obvious ways. But yeah, I think by the end of three years my critical thinking's just going to get better. Each time I realise a little bit more of how to like, approach something.

Evaluating arguments

The conclusions a writer has made, the reasons they have given for their conclusions and the assumptions that they have relied on all make up the writer’s argument, or line of reasoning. Once you can pinpoint this, it is time to start evaluating the argument’s effectiveness.

To do this, you need to reflect on the argument and ask questions.


Don't expect yourself to answer all these questions for everything you read or listen to. The point is to make sure that you are asking some questions and engaging in critical thought.

Logical and faulty thinking

Thinking logically

In logic, an argument can be valid or invalid. This is important for critical thinking because you can use it to determine whether an argument is one you should take seriously to or not.

A valid argument needs two conditions:

  1. All the premises upon which the argument is based are true.
  2. The conclusion can be shown to be the result of the premises.

For example:

  • John is a human. (premise - true)
  • All humans have brains. (premise - true)
  • Therefore, John has a brain. (conclusion - valid)

An invalid argument is one in which one or both of the conditions are missing:

  • The speed of sound is faster than the speed of light. (premise - not true)
  • The speed of sound is 343m/second. (premise - true)
  • Therefore, light travels slower than 343m/second. (conclusion - invalid because of a false premise)
  • Courtney is a fast runner.  (premise - true)
  • Courtney is a University of Sussex student. (premise - true)
  • Therefore, all University of Sussex students are fast runners. (conclusion – invalid as not the result of the premises)

Sometimes, the conclusion does not follow from the premises but in isolation is still true. In this case though, the argument is still invalid:

  • All seagulls are birds. (premise - true)
  • Some birds fly. (premise - true)
  • Therefore, all seagulls fly. (conclusion – invalid as not the result of the premises)

Examples like the last one are much harder to spot!
For practice with analysing logical reasoning, look at the LSAT and GMAT practice papers.

Faulty thinking

There are many ways that premises may not be true, or that conclusions may not follow logically from the premises given. Here are some explanations and examples of the more common ones. Look out for these errors when analysing academic texts and try to avoid these faults in your own arguments.


Criticising experts

 A lot of students worry about whether they really can question an expert’s opinions and data. The academic may have been researching and studying the subject for many years whereas you might simply be writing a 1500-word essay on the topic. Is it really possible to critique someone who is so much further along in their knowledge? The answer is yes, for the following reasons:

  • Critically analysing theories, pointing out issues with ideas, and suggesting methods of improvement are how scientific and cultural progress occurs. If people didn’t do this, people would still be using astrology to make medical decisions and travelling in bullock carts!
  • The fact that there are competing ideas and theories surrounding so many concepts in the world proves that academics disagree with one another. You can disagree too.
  • Other students, journalists, academics and thinkers question expert opinion all the time. They are not more intelligent than you.
  • You are not looking for the ‘correct’ answer when you think critically. You are only looking at what another person has said and deciding if it is something you can trust or not.
  • Academics can be wrong. There are countless examples of mainstream theories that have later been proven false. For instance: Dr Spock’s advice to parents in the 1950’s which caused thousands of cot deaths; Einstein’s stationary universe theory; or the centuries-long idea that Australia was the most southerly landmass on Earth.
  • Evidence can be poor. An expert might have carried out a well-designed research project and written up a convincing argument. But perhaps the sample size was very small or the research goes against what 100 other experts are arguing. While they might have made a good start, is the evidence enough to convince you?
Critical thinking does not always mean finding fault in someone else’s work. It can be finding what is good about it. If you can argue why someone is correct, this is also a demonstration of critical thought.