In order to write a well-argued philosophy essay, you must state your line of argument in the introduction of the essay and argue this point of view throughout, even in the conclusion. It is important to do this so that the reader can clearly identify your position on a topic and follow your argument throughout the essay. 

Also, it very useful to signpost throughout your essay. Signposting is letting the reader know what you will be talking about in your essay. For example, 'In this essay I will address three main criticisms of Plato's Theory of Forms. Firstly, I will discuss the infinte regress agrument. Secondly, I will look at the prisoner in the cave allegory. Thirdly, I will address the lack of physical evidence for the Theory of Forms.' It is clear to see that the essay will follow a specific structure because the route has been signposted to the reader.