What is a Thesis Statement?

Thesis statements are found right at the start of a thesis or dissertation, usually in the first couple of sentences. Informative and captivating, a thesis statement is similar to a hook line in a novel, though specific enough to detail the strict path the thesis will follow.

A strong thesis statement will help you stay on track throughout the writing process. Keep it simple by summarizing your paper in a couple of sentences at most. The statement must mention the topic, the author’s argument, and the evidence supporting the argument.


Since the thesis statement serves to both inform and spur the reader on, it is perhaps one of the most important sentences of any research paper. Whether your thesis or dissertation is argumentative or persuasive, both types should begin with a thesis statement tailored to the type of essay you’re writing.

Here are a couple of thesis statement examples written for analytical and explanatory essays:


An analysis of barn owl flight behavior reveals two kinds of flight patterns: patterns related to hunting prey and patterns related to courtship.

A reader who encountered that thesis in a paper would expect an explanation of the analysis of barn owl flight behavior, and then an explanation of the two kinds of flight patterns.


The lifestyles of barn owls include hunting for insects and animals, building nests, and raising their young.

A reader who encountered that thesis would expect the paper to explain how barn owls hunt for insects, build nests, and raise young.

Types of claims

The type of statement to open your thesis or dissertation will depend on your overall position and the context of the study itself. When writing an opening thesis statement, the type of sentence chosen will set forth how you’ll approach the topic. The opening claims fall under four categories:

  1. Fact or definition: to argue about whether something is a genuine fact.

 “A majority of the communities around the world rely heavily on oil, natural gas, and coal for their energy needs.”

2. Cause and effect: to argue whether x (e.g., object, person, event) caused y to occur.

“Increased emissions of greenhouses gasses, such as carbon dioxide, have led to an increase in the Earth’s average temperature.”

3. Value: determines the worth of something, as well as how valued it is and how it could be                      categorized.

“Climate change is safe to be one of the biggest challenges of mankind.”

4. Solutions or policies: a for or against argument to determine the best solution or approach              to solve a problem.

“The combustion of fossil fuels is by far the largest human source of global greenhouse gas emissions, releasing more than 30 billion tonnes of carbon dioxide (CO2) into the atmosphere each year. Reducing fossil fuel combustion is thus a top priority for climate policy.”

Your thesis statement should:

  • Take a position by being specific.
  • Merit further discussion. Your statement should be supported by evidence, and could contrast a widely-held view, thus generating debate.
  • Express one single idea or argument. E.g., “Though natural cycles of climate change have always existed, global warming is now thought to be man-made.”

How to be persuasive

Unless you’re writing an informative paper, all other types (compare/contrast, argumentative, narrative) will require a persuasive thesis statement. To be persuasive, the author will take a position on the topic and explain why they are correct. Consider the following example:

“Climate change is caused by human activities, such as the burning of fossil fuels, deforestation and farming.”

In this example, the reader understands the paper is about climate change and that human activities are the major cause of it. Hence, through the thesis statement, it is clear that the paper will explain and prove why these activities contribute to climate change. Broken down, the statement comprises the research topic and author’s opinion (i.e., that human activities cause climate change) and why (by giving three examples).

Useful tips

Be Specific

One or two sentences (approx 30-40 words) should be the limit of a thesis statement, so avoid wordiness and stick to two clauses: opinion and reason.


Your thesis statement is intrinsic to the type of thesis or dissertation you’re writing, so make sure you make an appropriate claim (fact, cause/effect, value, etc.)

Ability to be argued and demonstrated

To construct an argument, the structure generally follows three formulae:

  • x does y because of z.
  • Because of x, y happens.
  • Despite x, evidence shows that y happens.


The argument posed by the thesis statement may go against the majority view, so assertive language will add a bit more weight to the words.


Make confident statements in your claim. Avoid personal opinions (I believe/feel) and possibles (might/may). Instead, be authoritative in tone (x is like this because of y and z).