Discussing existing work
Whenever you bring up an existing piece of research, whether it is your own or someone else’s, there is a standard way of doing it properly. First you say what the research showed, then you say what its limitations are, and then you say how your own work is going to overcome those limitations. I.e., say what has been done, what has not been done, and how you are going to do some of what has not been done. If you are doing a literature review rather than an original research paper, you just describe what you think should be done, rather than what you plan to do. Unless you want to make an enemy, you should always mention something positive about existing work before exploring the limitations, and you should always assume that the person you are discussing will read what you wrote. Of course, sometimes there is a good reason to make an enemy, e.g. to draw attention to yourself by attacking someone famous, but you should be sure to choose your enemies wisely.
Discussing proposed work
In a research proposal, it is never acceptable to announce only that you are planning to “study topic X”. In the context of research, studying is a vague and unbounded task, with no criterion for success and no way to tell if you are getting anywhere. Studying is something you do in a course, where someone can tell you what to focus on and can test you to see if you got the right answer; research is not like that. In research, you need to spell out the specific questions you are going to try to answer, the specific phenomena that need explanations, and so on — it’s up to you to define the question and the methods, and until you’ve done so, it’s not research, just idle speculation.
In the discussion sections of a research paper, be sure to discuss all topics that the audience expected to see in the paper, even if you yourself do not believe them to be relevant. The reader is more likely to assume that you have been sloppy about your literature review than to assume you knew about the work but believed it not to be relevant. Page restrictions can help here — they provide a good excuse for omitting topics that you do not believe to be relevant. In a longer article or thesis without page limits you have no choice but to address the issue and explicitly state why the topic is not relevant despite the common belief that it is.
Dr. James A. Bednar. Tips for Academic Writing and Other Formal Writing