Unstated Assumption

Unstated Assumption Definition

Here's a simple way to see the unstated assumption.

Unstated assumptions are claims and reasons that the argument implies, nudging the audience to assume they are simply common sense and need not be critiqued. They often appeal to the values that the audience supposedly holds and the goals that the audience might desire.

In order to convince an audience, it is often useful to hint at the finer points instead of getting bogged down in the details and risk losing the audience's attention to the larger, more important conclusion. These implied points are often referred to as tacit claims, or tacit assumptions.

Recognizing an Unstated Assumption in an Argument

To recognize an argument's unstated and implied material, you should first point out what the arguer is trying to accomplish. Then consider why the arguer wants to accomplish that goal. By putting these two important parts into words, you can then examine how the arguer moves from one to the other. In order to articulate these in words, it is important to know the basic parts of an argument and how they work.

All arguments of all types are made of premises and conclusions.

Consider the following simple argument:

The stated premises are:

• Mrs. Dalloway's classroom has many windows.

• The windows of Mrs. Dalloway's classroom let in a lot of sunlight.

The stated conclusion is:

• Mrs. Dalloway's classroom is good for plants.

The unstated premises are:

• Sunlight is good for plants.

• Windows letting in a lot of sunlight is sufficient for Mrs. Dalloway's classroom to be good for plants.

From this example, we can see that the first unstated premise ("sunlight is good for plants") is a reasonable statement. Plants use sunlight to create energy by a process called photosynthesis. The second unstated premise, however, reveals potential problems for the original argument. Plants need more than sunlight to thrive: they need water and clean air, and if they are potted houseplants, they need people to take care of them. If Mrs. Dalloway's classroom has unhealthy air, no access to water, and no people around to care for the plants, then the conclusion (that Mrs. Dalloway's room is good for plants) will be untrue.

Fig. 1 - Unstated assumptions can be true or untrue

Unstated Assumption Examples

Here are a few examples of arguments with some of their unstated assumptions listed below.

This is a common-sense statement, but it does assume a number of things that could be contested if someone disagreed with its fundamental values.

A few claims that the argument implies or leaves unexamined:

• People drink and shower with water.

• It is good for people to drink and shower safely.

• Contaminated water makes drinking and showering unsafe.

• The responsibility for the quality and safety of Germany's water is Germany's responsibility, and not someone else's.

• Germany, as the name for a governing institution, is an entity that is separate from its citizens, and that entity bears responsibility for things like the safety of its water supply.

If the audience disagrees with any of these assumptions, then the main argument that "Germany should protect its water supply from contamination" would not make much sense to them.

This statement is much more controversial and complex, though at first glance it appears reasonable.

A few of the unstated assumptions here are:

• "Disability" refers to problems with strength and endurance. But there are mental disabilities which do not affect physical capabilities.

• All military services require strength and endurance. Many of a modern military's operations are technological and digital. Therefore, wouldn't a physically disabled person perform perfectly fine at a computer?

Types of Assumptions in Critical Reasoning

As you can see, there are many unstated assumptions that can be identified in arguments. Although there is no list of all types of unstated assumptions, it is apparent that assumptions often deal with how things are categorized, with suggestions for future courses of action and how something is valued.

Stephen Brookfield, a teacher and author on education, defined three types of assumptions that are usually made in critical reasoning. The three types are casual assumptions, prescriptive assumptions, and paradigmatic assumptions.

• Casual assumptions are the easiest to recognize and critique. They are assumptions we make about how things work and what we can do about them.
• Prescriptive assumptions are any assumptions that are stated with the word "should." They are assumptions about what course of action should be taken.

• Paradigmatic assumptions are the deep, unquestioned beliefs we have about the world. They are the most difficult to identify and critique because they make up the backbone of how we experience the world.¹

A perceptive arguer will be able to recognize, verbalize, and call into question each of these types of assumptions. Being able to identify and critique the third type, "paradigmatic assumptions," is the most important skill for success in critical thinking and analysis sections in English courses and tests.

Unstated Assumptions in Tests and Assignments

A major topic of English coursework is the evaluation and analysis of arguments. Both "free response" questions and "rhetorical analysis" sections require students to read argumentative texts and analyze how the writer's language choices build the text's intended meaning and purpose. In "evaluating arguments" sections, you can use the unstated material to reveal mistakes the arguer makes, faulty reasoning, and unexamined beliefs that compromise the argument's effectiveness.

Consider the following passage from an article in The Guardian:

Fig. 2 - Unstated assumptions may or may not be tricky

This paragraph clearly states the article's main complaint and its recommendations for addressing the problem. From an environmental standpoint, the logic is clear, and the suggested actions are reasonable. If you were expected to critique the argument and point out potential flaws, it would be easy to do so if you believed that plastic pollution was not a problem and protecting national parks was not important. However, if you agree with the values of the text, and you are expected to criticize the argument, then you have a more difficult task on your hands.

This is where identifying unstated assumptions comes in handy. First, identify the parts of the argument that point to a system of values.

¹ Stephen Brookfield. Becoming A Critically Reflective Teacher. 2017.

² Jonathan B Jarvis and Christy Leavitt. "Why are American national parks filled with plastic?" The Guardian International. 2022.