Using Evidence to Support your Argument

All university research and scholarship is based on evidence, and your own assessed work as a student is no different. To convince your marker that you know what you’re talking about, you can’t just make a statement and expect them to accept it; you will need to provide robust evidence to justify your point, show how you have arrived at your conclusions and prove that it’s based on solid grounds. Everyone is entitled to their own opinion, and we are interested in your ideas, but you need to supply proof and show how it supports your statement, to persuade others of what you think. You might have seen this reflected in marking criteria, assignment guidelines or feedback that say you should ‘use evidence’, to ‘support your argument’ and ‘back up your point’.  

What counts as evidence?

The most universal way to support a point is to provide a reference to a source which backs it up: either someone who agrees with you, or evidence that supports you. As your studies progress, this strategy may need to become more in depth, perhaps referencing multiple sources or commenting critically on them. One reference is good, but might be overly selective, ignoring contradictory or better sources. A carefully chosen reference from a highly regarded study or scholar is even better, and best of all is not one, but several sources which demonstrate a weight of evidence building up. More than three or four references starts to become a bit redundant though – the point is made!

What counts as acceptable evidence will vary depending on your subject. Arts and Humanities are based in more subjective argument and interpretation; Social Sciences often draw on qualitative and quantitative data, and Physical and Medical Sciences from empirical data. In some instances, your own personal experience can count as valid evidence, if you were writing a reflective assignment, for example, but it would not be appropriate if writing a report as it might not be representative, and cannot be verified by the reader.  

Common knowledge

You don’t have to back up absolutely everything you say with evidence (or you’d soon run out of wordcount to advance your own point properly!). Some things are common knowledge. That could mean that a fact is just generally known by everyone, and not disputed or in doubt. This could include:

• facts such as London is the capital of the United Kingdom
• well documented dates such as the start of the First World War in 1914
• H₂0 being the chemical formula for water
• things which everyone knows from their lived experience, such as the sky is blue.

Common knowledge could also mean a generally known fact in your specialist field of study, not necessarily known to lay people, but accepted as a basic, fundamental knowledge by everyone in your discipline. However, the higher your level of study, the more you can take specialist general knowledge for granted. A PhD student can be assumed to know the basics and not need to back them up, but a first year undergraduate might have to prove to their lecturer that they do understand what they are talking about, with a reference. If you aren’t sure if something is general knowledge or not, look at the texts you are reading and see if they include a reference to that fact or not. If not, it’s probably generally known. And you might need a reference to general knowledge that comes from outside your own subject.  

Have I backed my point up?

To check if you’re supporting your own points with evidence, imagine that the reader is asking you after each statement that you make, ‘how do you know that? How can you be sure of that?’ If you have included something in your writing which robustly answers this question, then you’ve backed your point up. If not, think about what kind of evidence you could provide that would satisfy the reader.

You may not be able to find a citation that does exactly what you need it to do, but that doesn’t mean you can’t back your point up; a reference isn’t the only way to do this. You don’t have to find someone else who has said it first; you can make your own points in your own right too, if you support them. This becomes more true as you progress to higher stages of study. Think about your answer to the question, ‘How do I know that’, and what kind of evidence would best suit your purpose: 

How do I know that?

• ‘I read it’. Then show the reader where you read it, with a reference 
• ‘I worked it out based on something I read’ Then reference the data or opinion you based it on and explain how you built on that evidence with your reasoning. 
• ‘I worked it all out myself’Then show your reasoning in full.  
• ‘I saw it in my own research’ Then show the reader your own supporting data or sources that you have collected with your analysis (this is more likely in a dissertation or research report or project where you have time to do your own research)
• ‘I don’t know – I just know! Don’t we all know that?’ Then this might be general knowledge (if you’re sure we all know that!) 

All of these are valid ways to back up your own points, but some require you to do original research, which might be outside the scope of your assignment, or disproportionate to the importance of the point you’re making!

Using evidence to support your point

Sometimes it’s enough to include a reference at the end of your sentence, but at other times, you might need to do more than just add the evidence. Evidence doesn’t speak for itself, but often needs to be explained, analysed and interpreted so that the reader understands how it supports your point. You might feel that the reader can work it out for themselves, but it’s your job as the writer to do that work, not the reader. You might after all see it in different ways, and you want the reader to follow your reasoning and see it as you do. As you write or edit your draft, ask yourself:

• What does this evidence mean to you? How should the reader interpret it? Why is that interpretation the most convincing one?
• How does this evidence support your argument? 
• To what extent does it support you? Are there any limitations or gaps you want to address or acknowledge?
• What are the implications of this evidence for your argument? “So what”?

Conflicting evidence

Sometimes we find evidence that actually contradicts what we want to say and our natural reaction might be to ignore it and hope that the reader isn’t aware of it. However, you can actually strengthen your work by acknowledging that conflicting evidence. Briefly explain why you think it is not as convincing or does not actually undermine your case, dismiss it and move on. This shows that you can critique your own work; you have considered various possibilities, actively looked for counterarguments, tested your thinking and have come to a carefully considered conclusion. Of course, if you can’t counter the conflicting evidence, then you might need to rethink your point!

What to do when you can't find evidence

Alternatively, you might not be able to find the evidence you need to support your claim. This might mean various things:

• that you need to broaden your search strategy (but set yourself a cut-off point so you don’t look for so long that you run out of time for the rest of your assignment)
• that what you assumed to be true isn’t quite right (in which case, you might need to do more reading and thinking)
• that no-one else has claimed or demonstrated this yet (which might be an opportunity to do some original thinking of your own, if you can evidence it and have time to research it).

Before you invest time in these options, consider how key the point is to your overall assignment. Is it essential or just a side issue?