The principle of modularity (one idea per element) can help to simplify scientific communication. 

Modularity involves building arguments from elements (e.g. premises and arguments) that are self-contained. Therefore, making sure that each element contains ONE (and only one) main idea can contribute to clear, modular presentation. 

Sentences and Paragraphs are the basic elements of writing (Strunk and White, 2000). Therefore, it is useful to consider some ways to help write self-contained sentences and paragraphs.

1) SENTENCES: ensure that the TYPE of each sentence is well-defined.

In a reasoned framework, most sentences are one of a small number of types. Specifically, most sentences are either

     A) A PREMISE, supported by a reference to your data or a peer-reviewed quantitative research study (references placed parenthetically at the END of the sentence).

     B) A CONCLUSION, based on clear deduction or induction from supporting premises. For clarity, conclusions can be identified using words like "Therefore" at the start of the sentence.

Therefore, the majority of a scientific paper is constructed from only TWO types of sentences: premises and conclusions. How can we ensure that premises and conclusions are self-contained?

Sentences that are self-contained premises clearly and succinctly state one important piece of information or main idea. For example:

"The spring index was significantly larger than the strut index (p<0.001; Table 1)" expresses one piece of information

"The spring index was 61±11%, significantly larger than strut, motor, and damper indices (p<0.001 for all comparisons; Table 1)" presents four pieces of information that naturally group together to form one main idea.

Similarly, a main idea can be the conclusion from your own reasoning or from published research. For example:

"The ankle joint is the primary work generator during human walking (Herr and Grabowski, 2012)."

Sentences that are premises can be identified by parenthetical references at the end of the sentence (Brand and Huiskes, 2001). If a sentence in a paper does not have a reference, then make sure it is a conclusion sentence, or clearly some other type such as a transition. If the sentence is not playing a clear role in the argument, then it is probably time to question whether the sentence is necessary.

Sentences that are self-contained conclusions directly follow a series of premises (linked together with logical transitions). Conclusion sentences also begin with identifiers such as "Therefore" or "Consequently." For example:

"Therefore, smoking increases the risk of developing cancer."

In addition to premises and conclusions, reasoned arguments can include a limited number of clarifications (e.g. definitions, examples and summaries). Clarifications should also be self-contained and NOT refer to other parts of the paper. In scientific papers, clarifications also commonly require references.

In addition to clearly identifying the purpose of each sentence, it is also important to make sure that sentences are written simply and specifically. A simple rule of thumb that can help ensure that sentences are self-contained is:

Use ZERO or ONE commas per sentence. Occasionally, commas can be helpful to distinguish between transitions and premises. However, additional commas may indicate that the sentence is expressing more than one idea. Therefore, it is clearer to use separate sentences that each express one main idea instead of using two commas (Strunk and White, 2000). Limited exceptions to the principle of at most one comma per sentence include list frameworks, where individual elements of the list may be separated by commas.

2) PARAGRAPHS: ensure that the PURPOSE of each paragraph is well-defined.

Paragraphs are fundamental building blocks of papers (Strunk and White, 2000). Arguments are the fundamental structures of reasoned frameworks (Bilsky, 1963). Therefore, a reasonable approach to writing is to create paragraphs that are self-contained and present ONE reasoned argument. The conclusion of the argument usually follows the premises at the end of the paragraph. 

However, to simplify writing (and reading), it is also helpful to use a "topic sentence" for each paragraph. Topic sentences are commonly the first or second sentences of a paragraph, and communicate the purpose of the paragraph to the reader. For scientific writing, BOTH the topic sentence and conclusion of the paragraph should express the SAME main idea. 

Why have two sentences expressing the same idea at the beginning and end of a paragraph? 

     A) Topic sentences help with writing. As an author is writing a paragraph, the topic sentence can help guide the argument. The topic sentence identifies the goal of the paragraph. Therefore, a topic sentence can be helpful for deciding what information contributes to the argument and what information does not.

     B) Topic sentences use repetition to provide emphasis. Repetition can help readers step back and understand the main conclusions of an argument despite potentially complex premises.

     C) Topic sentences help authors use outlines to structure papers. Powerful outlines use conclusive statements for each section of the outline. Using topic sentences allows authors to directly use much of the text of an outline in the paper itself.

If a paragraph is bounded by conclusive sentences expressing the same main idea at the beginning and end, then clearly each paragraph should defend that single main idea. Therefore, topic sentences can contribute to clear, modular writing.

To simplify writing, make sure that each element has a well-defined purpose. Most sentences are either clearly-defined premises or conclusions that construct reasoned arguments. Each paragraph defends a single conclusion, identified at the beginning and the end of the paragraph.