Guidelines for Writing a Philosophy Paper

A good philosophy paper addresses a specific question by providing evidence relevant to that question, arguing for a particular interpretation of that evidence, and demonstrating that alternative interpretations are weaker.  Your job is to argue for your position in such a way that your reader sees what is at stake, understands precisely what you want to claim, and concludes that your position is the most reasonable and best supported one among the viable alternatives.  You should not merely state your opinion; you must provide a reasoned defense of it.

A good philosophy paper is, above all, clear, even at the expense of rhetorical elegance. You do not have to make earth-shatteringly original claims; your main goal should be to establish a relatively small point beyond doubt.  A good target audience for your paper is someone who read or thought about this material a long time ago, and who holds a position different from yours, but can't quite remember why.

Here are some more specific guidelines:
1. Answer the question. 
A classic way to write a bad philosophy paper is to state a question X, say something like "Before we can address X, we need to examine Y", and then fail to return to X.  Get right to the point, avoiding general introductions like "For countless centuries man has pondered the delicate issue of X."  Just state the problem and explain why it matters.  If you are writing on an assigned topic, note which topic you are answering at the beginning of your paper.

2. Be clear.
Use short sentences.  The structure of your paper should be fully explicit and easy to follow; it is a good idea to state that structure in the first paragraphs of the paper.  Make one point per paragraph, and explain the connection between one point and the next.  Don't be afraid to use relatively clumsy transitions like: "I've just shown that X is committed to the claim that P.  But P is implausible. I will now present two arguments to show that not-P." Be explicit about which claims you are asserting and which you are attributing to your opponent; avoid vague formulations like "One might think that...": who might?

3. Be precise.
Avoid jargon, and define all technical terms.  Much of philosophy consists in arguing over the meanings of words; so you want to make sure your reader understands just what you mean by what you say.

4.  Be relevant.
Make sure that everything you say contributes to answering the question, and explain how it does so.

5.  Support your position with evidence.
The two main sorts of evidence are textual citations and examples.  Neither sort of evidence can stand on its own: you need to state explicitly why this quotation or thought experiment supports your position.

6.  Consider objections and alternative positions.
Don't be afraid to raise real objections to your own position, even if you can't fully respond to them.  It's much better to show that you're aware of this difficulty than to hope your reader doesn't notice it.  Make sure the objections and alternative positions are as strong as they can be.  This is important for two reasons: first, it advances everyone's understanding more effectively, and second, it gives you a better shot at really resolving the issue.

7. Critically evaluate all arguments.
This can involve several aspects: articulate any hidden premises behind the argument.  Ask whether the premises on which the argument depends are true.  Ask whether the argument is valid: that is, whether the conclusion really does follow from the premises.