A philosophy essay is never a mere report, nor a presentation of your opinions of someone else's opinions, but should be both analytical and critical. It is analytical in the sense that it presents a careful examination of the topic, and tries to make complete sense of it. Therefore a philosophy essay always goes beyond a mere presentation of the "facts" in the case. You should attempt to dig below the surface of what you have been given, whether it is a particular issue or a particular text. If you are criticizing an argument, don't judge merely by your immediate impressions of what you have before you, but try to get behind what is being said, and perhaps even find a way of putting an argument in a clearer way than what is given.
In short, you should not merely present what the issue is or what the author says: you should go beyond this to answer the question why. Indeed, the two questions are interlinked: if you don't understand why a particular claim is being made, you will fail to explain properly just what is being claimed.
If you persevere in asking the question "why," your essay will be critical as well. Criticism is not just refuting arguments: some of the best criticism lies in making the best possible case for arguments that, on the surface, do not seem to work. Only after you have made the best possible case for an argument can you claim that the argument is faulty or inadequate, if you find it to be so. You may indeed find that the argument does not work. Demonstrating the inadequacy of arguments is an important kind of criticism. But remember that demonstrating that an argument is not refuted by apparent objections is an equally valid kind of criticism. It is important to stress that criticism is not just stating an opinion: critical writing does state an opinion, but it is a reasoned opinion.
Your essay should have a clear structure. This is indicated in the first place by a title. It should then begin with clear statement of a thesis. This states what you are trying to prove, or what your focus is. You do not need to prove some extraordinary or startling point, but your essay should be about something definite. Your reader needs to know why you are moving from one apparently different topic to another in the body of your essay. A clear statement of your intentions in your paper will help to orient your reader. At its simplest form, a thesis may be simply a statement of how you intend to answer the essay question as posed.
After stating your thesis, you should proceed to the main body of your essay. In this section the relevant texts or issues are presented and discussed in order to show that the main thesis is true. This is important: if any material in your essay does not somehow clarify or support your thesis, it does not belong there. Make sure you make clear how your material is relevant to your topic.
Remember too that your thesis is probably not as self-evident as it appears to you. You will need to argue your point. If you are making a claim about a text, such as saying that an author said something or meant something, this needs to be proven. Support your claim with a quotation or a citation. If you use a quotation, be sure to indicate it. Quotations should not be longer than four or five lines of single-spaced text. If you want to claim that a certain position follows from what an author said, you must demonstrate that this is either what the author meant, or else it follows as a necessary consequence from what he said. Make sure that all your claims are supported by arguments, textual references, or both.
If you come across arguments or evidence that suggest that your thesis might not be true, rather than ignore or suppress such arguments or evidence, you should argue why they do not disprove your thesis. This strengthens your case. If any argument against your thesis does have some merit, but not enough to disprove your thesis entirely, you may want to qualify your thesis in some way. This is not an admission of philosophical weakness, but an indication of philosophical honesty. It will also help clarify the issue for your reader. In general, ask yourself what questions your reader might have, and ensure that these questions are answered.
The body of the essay is followed by a conclusion which restates the main thesis, and notes any developments that have appeared in the course of the essay. Your conclusion should make clear how you have answered the general question of the essay.
Unless you are specifically told otherwise, secondary sources are optional. The important thing in your essay is that you demonstrate that you can think for yourself on the topic. Never treat secondary sources as an authority: the fact that someone else said it doesn't prove the point. Remember that notes or commentaries written by an editor or translator count as secondary sources too. Furthermore, don't assume that just because a book is in the library that what its author says is true: you can find many contradictory claims in library books. This is even more true of sources you find on the Internet: anybody can have a web page, no matter how stupid, foolish or ignorant they might be. Always trust your primary sources over secondary sources. The most important thing is that all your points must be argued, although secondary sources might help you to argue. Use secondary sources to shed light on points you find difficult, to provide a better way of making a good point than you can find yourself, or to provide a position that you intend to attack. In short, secondary sources must always remain secondary.
The source must be cited for all quotations. Moreover, all expository passages which summarize an author's views should be noted. Your note should make clear the book and the page from which the passage comes. Any standardized style is acceptable (footnote, end-note, internal note) as long as it is clear, logical and consistent. If you are summarizing or quoting a secondary source, the author should be identified in the body of the text. Do not cite your lecture notes as proof for a position (there is far too much margin for error). There should also be a bibliography that states every source that you found useful.
It is important to note that using any source, in whole or in part, without giving credit to it constitutes plagiarism. Using any uncredited source whatever, as a source of wording, ideas or general structure, is a sufficient ground for failure in this course and for further academic discipline.