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Thesis Statements 

After you’ve narrowed your topic, you must create a thesis. Your thesis is your argument and/or the answer to your research question and it belongs in your introduction. The body of your essay will prove why your thesis is valid using specific evidence from your sources. 

Thesis statements must be arguable. This means people could reasonably disagree. You must be able to argue that your thesis is reasonable, supported by evidence, and worthy of taking seriously. 

  • Not a thesis statement: McMaster maroon is the best colour. 
  • This is an opinion and not arguable. 
  • Not a thesis statement: The United Nations was formed in 1945. 
  • This is a fact and not arguable. 
  • Thesis statement: Professional hockey has helped create a Canadian identity. 
  • This thesis statement makes an arguable claim that must be proven with evidence and analysis. An even better thesis statement would also consider how hockey has done this, what kind or element of Canadian identity, and why it’s important. 

Thesis statements must be specific. You need to be able to support your thesis with evidence from reputable sources. What are your sources’ main arguments? Where do your sources agree? Which claims are controversial? The answers to these questions are jumping-off points for your own thinking. 

  • Not a thesis statement: Einstein was the greatest physicist of all time. 
  • This is not a thesis statement because it contains a value judgement: a simplistic assessment of “good” or “bad” based on opinion, not evidence. Instead, choose one of Einstein’s theories and carefully examine its merits in the context of physics. 
  • Not a thesis statement: Throughout history, people have enjoyed music. 
  • This is not a thesis statement because it’s too broad. Avoid generalizations like “throughout history,” “in society,” “humankind,” etc. Instead, consider a specific group of people from a well-defined place and time. 
  • Thesis statement: Henry Ford’s assembly line had a negative impact on working-class American families in the early 1900s. 
  • This is a thesis statement because the argument is grounded in a particular place, time, and group of people. An even better thesis statement would also consider what kind of negative impact and why it matters in the context of the topic. 

It’s okay if your thesis changes as you research. You should expect to revise your work as you go along! 


Improve your writing and study skills! Book an appointment with a writing advisor and/or academic coach on OSCARplus.  Questions? Email


Buckley, J. (2009). Fit to print: The Canadian student’s guide to essay writing (7th ed.). Nelson. 

Trent University (n. d.). Topic and thesis development. Retrieved from 

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