Specific writing involves choosing words with clear referents and appropriate scope.

Three principles for word choice can help make writing more specific:

1) Only use words with specific referents.

2) Use helping verbs and adjectives to make sure that sentences have appropriate scope.

3) Avoid vague or confusing words.

1) Only use words with specific referents.

The "referent" of a word is the object or concept that the word refers to. In specific scientific writing, words have clear, straightforward referents. For example: "Santiago Ramón y Cajal introduced the term “neuronal plasticity” to describe nonpathological changes in brain structure" has a clear referent: the neuroscientist Santiago Ramón y Cajal. 

In contrast, the sentence "Various neuroscientists have used the term “neuronal plasticity” to describe nonpathological changes in brain structure" does not have a clear referent and is not specific. The neuroscientists who have used the term remains unknown. Because of the vague referent "various," the sentence conveys very little meaning and introduces confusion instead of clarity into a text.

Similarly, writers sometimes use minimally-informative phrases such as "Previous research has shown...," in arguments. Readers generally know that research has happened in the past, so identifying research as "previous" does not convey important information. Moreover, shifting the focus to the "research," instead of the conclusions of the research, is distracting. Therefore, removing phrases like "Previous research has shown" can clarify text and strengthen arguments.

Sometimes writers are tempted to use vague nouns in a misguided attempt to make their writing sound more formal. For example, the sentence "Several important factors affect learning" may seem authoritative. However, in reality the sentence offers very little information to the reader. Moreover, scientific writing does not require effort to sound authoritative. Authority in scientific writing comes from strong reasoning and specific premises, not from writing style. Therefore, vague statements that are meant to sound authoritative actually cause scientific writing to be LESS respectable.

Other common words that are also used as vague subjects are "Aspect," "Area," Situation," "Consideration," "Degree," "Case," etc.

Other commonly-used vague subjects are "Various," "Variety," and "Plethora." All three words are commonly used in a vague way without a clear referent. To make most arguments more specific, words like "various" should be replaced with more specific attributes of a group or specific referents. For example, instead of writing "I have worked with various patients during my internship," it is often stronger to argue "I have worked with a diversity of patients during my internship" and then provide specific evidence for your claim to working with a diverse population. 

Clear sentences identify the specific referents. For example, the problem with the sentence "Several important factors affect learning" is not with the word "factor" itself, but because the sentence lacks specific referents that specify the meaning of "factor." "Factor" can be used in a more specific way. For example, the sentence "Among the factors that affect learning are (1) student motivation; (2) prior student knowledge; and (3) learning environment" uses a list framework to identify three contributors to learning. The word "factor" helps to indicate that the three identified contributors are only a subset of larger group of factors that affect learning. Therefore, nouns like "factor" can be helpful if part of specific statements, but are NOT specific enough to act alone as subjects for sentences.

APPLICATION: To write specific sentences, make sure that every word has a specific, clear referent. Avoid vague nouns that are not immediately specified by connecting the noun to a clear referent.

2) Use helping verbs and adjectives to make sure that sentences have appropriate scope.

The concept of scope was helpful to understand how to ensure that paragraphs can be self-contained (remember that "Scope" is the range of a content where an element of information applies). The concept of scope is also useful for selecting helping verbs to help ensure that sentences are truthful. For example, consider the sentence 

"Smoking causes cancer."

The sentence "smoking causes cancer" seems like a straightforward, factual statement. However, for scientific writing, the sentence "smoking causes cancer" is not truthful because the sentence is not specific enough.

The sentence "smoking causes cancer" is vague, because it does not identify when smoking causes cancer. Because the sentence is such a simple declarative, it implies "smoking ALWAYS causes cancer," which is not true. The scope of the sentence is too broad. Therefore, the sentence needs a helping verb to make it truthful: "smoking can cause cancer." The helping verb "can" changes the sentence from an unsupported (unsupportable) generalization into a true statement about smoking.

Helpful helping verbs include: "can," "could," "must," "may," "might." 

Similarly helping adjectives can also be useful for making sure that every sentence has a truthful scope. For example, consider the sentence:

"Insects have four wings."

Again, "insects have four wings" seems like a specific, clear sentence. One problem with the sentence is that it is not true. Although most types of insects have four wings, one important order (flies) does NOT have four wings, but two. Instead of two of their wings, flies have modified sensory organs called "halteres" that help flies be extraordinarily stable and maneuverable (Pringle, 1948). Therefore, the sentence "insects have four wings" is not specific enough to include in a scientific paper.

To make our sentence about insects more specific, we could add an appropriate adjective. The adjective that we select depends on the strength and specificity of the statements that we make. For example, sentences with adjectives that specify their scope to different degrees include:

"Some insects have four wings" (very vague scope)

"Many insects have four wings" (somewhat vague scope)

"Most orders of insects have four wings (specific scope, but only if you have evidence that that more than 50% of insect orders have four wings.)

"Only insects in the order Diptera have two wings" (very specific scope, but not necessarily true depending on how you define "wings:" most beetles use only two wings to fly for example.)

Using sentences with very vague scope is safe, but not very specific and powerful. Clearly, stronger adjectives like "most" or "only" are preferable if evidence supports the statement. It is best to choose the most specific, informative sentence possible. However, it is necessary to write a truthful sentence. Therefore, truthfulness is the most important criterion, and statements can only be as strongly worded as direct evidence allows.

APPLICATION: Use helping verbs and adjectives to ensure that sentences are truthful. 

3) Avoid vague or confusing words.

Selecting appropriate words to express ideas that are both truthful and specific is clearly important for scientific writing. Conversely, avoiding words that result in vague, non-specific statements can also help to make sure that writing is specific. Some common types of words and expressions that are vague and should be avoided are:

A) Exaggerated or hyperbolic statements: Scientists very seldom have the luxury of making broad categorical statements like "All people breathe," and most categorical statements that we can make are trivial. Therefore, avoid the words "All," "None," "Everyone," "No one," "Always," "Never," or any of their variants. 

B) Desires or beliefs: Science is based on using specific evidence to come to conclusions through reasoning. Although some assumptions are necessary for every scientific study, assumptions should be identified and justified. Beyond the assumptions necessary for a study, the beliefs and desires of the scientists should NOT be relevant to the argument. Therefore, there is seldom good reason to use terms such as "want" or "believe."

C) Subjective judgments: Scientific comparisons require specific (usually quantitative) measurements. For example, statistical tests can establish whether one average value is significantly "less" or "greater" than another average value. However, scientists typically avoid using subjective judgments for comparisons in scientific papers. Therefore, avoid the terms "better," "worse," "good," "poor," "beneficial," "detrimental," and their variants. 

APPLICATION:  Exaggerated or subjective words are vague and confusing. Avoid words that express desires, subjective judgments, or exaggerations.