This page is to help guide you in the art of writing a good position paper for computer science. This paper has some good guidelines in for position papers in general.
A reasonable sample position paper can be found here. The paper's position is that all programs will hit a fundamental "memory wall" which will limit performance. However, another very good rebuttal position paper argues that in fact, no such memory wall exists.
First, make sure to articulate your position clearly. Most good position papers will elaborate on the positions for the class. If not, they will at least explain what the position means in 1 paragraph, at least.
Second, for a good computer science paper, you should have some quantitative argument, if possible. A list of anecdotes is not all that persuasive in support of a position. Sometimes, you can't directly measure something, but an indirect observation might support your argument. For example, some people have made the argument that performance isn't as important as it used to be because the difference between the average selling price of a PC and the most expensive PC have diverged over time. While not proving the argument, the thesis fits the facts better than some alternative explanations.
Third, be careful of using counter-examples to argue against a position. For example, a position of the form "X implies Y" and then coming up with an example of "not Y" doesn't say anything about statement X. Counter example can be quite useful, but make sure the position is clear enough that the counter-example is meaningful.