A standard journal article consists of about forty paragraphs. A standard paragraph consists of about six sentences. When I went to school, we were told that a paragraph should have a "topic sentence" and a "concluding sentence". (Here's a classic description.) About a year and a half ago, however, I read Tara Gray's Publish and Flourish, which convinced me to think in terms of "key sentences" instead. This method has the advantage of allowing you to easily generate an "after-the-fact outline", which is an enormous help in putting your paragraphs together to form a coherent argument.
Think of each prose paragraph as an argument in its own right. The key sentence is the conclusion of the argument, the proposition you want your reader to come away with. It will not always be a matter of getting the reader to believe something, however. You might only want the reader to understand something or entertain something for the sake of argument. But this ambition will normally be seen in the content of the proposition. There is a difference between a key sentence that says "The recession is over" and one that says "Jeff Frankel has declared the recession to be over". If you want the reader to question it, the key sentence might even be a question: "Is the recession really over as Jeff Frankel says?" These key sentences require different kinds of support, which is to say different paragraphs to support them.
Like I say, a paragraph offers about five sentences worth of support for a key sentence. Six sentences in all. That's a useful way of thinking about your finitude as the writer of a journal article. You are making about 40 claims, each of which can be adequately supported by five sentences. The adequacy of the supporting sentences (the bulk of a paragraph) depends almost entirely on context, i.e., your field.
You know you're taking the craft of writing a journal article seriously when you are thinking about what your forty key sentences are. Having identified them in a first draft of your paper, you now ask yourself whether each of them can reasonably be supported (in the face of the predictable concerns, questions, and criticisms of your field) with about five sentences. And, conversely, whether each of them really needs such support. A sentence that doesn't need further support should not be a key sentence.
A sentence that needs much more* than five sentences of support needs to be broken down into lesser claims. Could it not, then, you might ask, constitute the key sentence of a section? Yes, sort of. Each of the supporting sentences of this paragraph, which will likely be the opening paragraph of the section, will now provide the content of the key sentences of the rest of the paragraph. But in that case the key sentence of this first paragraph will, at least implicitly, have the section as is subject: "This section will deal with five key difficulties of applying phenomenology to organization studies."
In most cases, there are more elegant ways of doing this that actually meets the first standard of making claims that only require five sentences of support. "Scholars have traditionally been hesitant to apply phenomenology to organization theory." This statement can be supported with reference to relevant theorists and the problems they have raised, which will normally be adequate to support the claim about their hesitation. Assuaging their concerns (dealing with the difficulties they imply) is another matter, but you've now given yourself 25 sentences to do so instead of 5.
On Wednesday, I'll look at an example.
*Update: I've added the qualifier "much" here, and I'd also like to emphasize the word "needs". Sometimes a twelve-sentence paragraph is perfectly justified. But it won't, properly speaking, need all those sentences. It's just extra detail that you know the reader will appreciate. This sometimes happens when you are reporting data, or presenting a close reading of another text.