Aristotle, Nicomachean Ethics, Book 2, chapter 5. (1105b19-1106a13)
       Next we must inquire into what virtue is. Since the things that occur in the soul are of three kinds--passions, capacities, and states--virtue must be one of these. By passions, I mean, desire, anger, fear, boldness, jealousy, joy, friendly feeling, hatred, longing, zeal, pity, and, in general, those things that pleasure and pain accompany. Capacities are the things in virtue of which we are said to be capable of experiencing passions, such as the capacities in virtue of which we are capable of becoming angry or distressed or feeling pity. States are the things in virtue of which we are disposed well or badly with respect to the passions, such as, with respect to anger, if we are disposed to feel it violently or weakly, we are badly disposed with respect to anger; if we are disposed to feel it moderately, we are well disposed, and similarly with respect to the rest of the passions.
       Now neither the virtues nor the vices are passions, because we are not said to be good or bad on account of the passions, but we are said to be good or bad on account of virtues and vices; and because we are neither praised nor blamed on account of the passions (for neither the person who feels fear or anger is praised, nor is a person blamed simply for feeling anger, but for feeling it in a certain way), but we are praised and blamed on account of virtues and vices.
       Further, we feel anger or fear without choice, but the virtues are choices, or involve choice. In addition, we are said to be moved on account of the passions, but on account of the virtues and the vices we are not said to be moved, but to be disposed in a certain way.
       For these reasons, neither are the virtues and the vices capacities. For we are not said to be good or bad simply because we capable of experiencing passions, nor are we praised or blamed for this. Further, we are by nature capable of experiencing the passions, but we do not become good or bad by nature (we discussed this earlier).
       So if the virtues are neither passions nor capacities, then it remains for them to be states. Thus we have stated what virtue is with respect to its genus.

(Tr. C. Bobonich)

Argument Reconstruction:

Note that an argument reconstruction involves careful reading, re-reading, and dissection of the passage. The reconstruction must be revised multiple times before it becomes a coherent, valid, and successful extraction of the author's argument. The following reconstruction has been re-worked several times; it was not in the form below on the first attempt.

1. Things that are found in the soul are of only three kinds: passions, capacities, and states. (P)
2. Virtue is found in the soul. (P)
3. Therefore, virtue must be a passion, capacity, or state. (from 1 and 2)
4. We are not called good or bad on the ground of our passions. (P)
5. We are called good or bad on the ground of our virtues. (P)
6. Therefore, virtue is not a passion. (from 4 and 5)
7. We are neither praised nor blamed on account of our passions. (P)
8. We are praised and blamed on account of our virtues. (P)
9. Therefore, virtue is not a passion. (from 7 and 8)
10. We feel passions without choice. (P)
11. Virtue is or involves choice. (P)
12. Therefore, virtue is not a passion. (from 10 and 11)
13. On account of the passions, we are said to be moved. (P)
14. On account of the virtues, we are not said to be moved. (P)
15. Therefore, virtue is not a passion. (from 13 and 14)
16. Capacities are the things in virtue of which we are said to be capable of feeling these, e.g. of becoming angry or being pained or feeling pity. (P)
17. We are neither called good nor bad, nor praised nor blamed, for the capacity of feeling the passions. (P)
18.  We are called good or bad, praised and blamed, for our virtues. (P)
19. Therefore, virtue is not a capacity. (from 16, 17, and 18) 
20. We have the capacities by nature. (P)
21. We are not made good or bad by nature. (P)
22. We are made good by nature if and only if we have virtue by nature. (P)
23. We do not have virtue by nature. (from 21, 22)
24. Therefore, virtue is not a capacity. (from 20, 21, 22, and 23)
25. Therefore, virtue must be a state. (from 3, 6, and 19)

Explanation:

When reconstructing an argument, follow these steps:
Step 1
       Locate the conclusion and establish the location of the argument for the conclusion.  In this example, the first step, locating the conclusion, can be done by reading the passage, then determining Aristotle’s goal in this passage.  We see from the first sentence that Aristotle will be considering what virtue is.  Now that we know what he is trying to determine (he is trying to classify virtue), we can scan the passage until we find the place where Aristotle has determined the nature of virtue (since that will be his conclusion to the argument).  Upon scanning, we see the conclusion at the very end of the passage—the second to last sentence.  Aristotle set out to consider the nature of virtue, and, at the end, determines that virtue is a state.  In this case, the argument is in a very straightforward style, with the conclusion at the end and the argument for the conclusion before that, but this is frequently not the case.  Sometimes, the conclusion is at the beginning of an argument, sometimes in the middle, and sometimes the conclusion is absent and must be supplied by the reader based on the premises.
Step 2
       Establish the structure of the argument as a whole.  That is, we can note that Aristotle plans to show us the conclusion- that virtue is a state- by showing us, first, that virtue must be a passion, capacity, or state and, second, that it is neither a passion nor a capacity, thereby proving that it is a state. 
Step 3
       Analyze each section of the argument or subargument.  In the case under consideration, the first paragraph lists the three things found in the soul and.  From the second sentence alone, we can derive the first section of the argument (1, 2 and 3).  There is an implicit premise in that second sentence which must state that virtue is found in the soul.  Aristotle implies this when he states that “virtue must be one of these” in reference to the three things found in the soul.  We need to supply this premise in order to complete the argument.
       The rest of the argument is one form only.  All subarguments list qualities of passions and capacities that do not belong to virtue, showing us that virtue could not possibly be identical to a passion or capacity because it does not have all qualities in common with faculties and passions.  Specifically, the second and third paragraphs prove that virtue is not a passion by comparing passions and virtue.  Each subargument in paragraphs two and three is one conjunction, joined by the word “but”, and that the first conjunct of each conjunction is the first premise and the second conjunct is the second premise.  If we follow this trend, then all arguments proving that virtue is not a passion can be explicated by splitting these conjunctions.  This section of the argument in which virtue is shown to not be a passion is probably the most simple to dissect because it contains no implicit premises.
       The fourth paragraph proves that virtue is not a capacity, a slightly more complex because it does contain implicit premises.  The first argument in the fourth paragraph only states that we are not called good or bad, praised or blamed, for our capacities; but, it implicitly argues that we are called good or bad, praised or blamed, because of our virtues.  We know that this is a supplied premise because we can tell from the structure of the rest of the argument, especially the previous section, that Aristotle is contrasting virtue and the capacities.  Once we recognize this strategy of contrast, we can supply the premise that contrasts with the statement about our capacities.  That is, we can make the implicit argument that we are called good or bad, praised or blamed, because of our virtues.  The second argument of the fourth paragraph is more difficult to validly reconstruct. It states that, while we have the capacities by nature, we are not made good or bad by nature.  This argument needs the implicit premise that we become good by nature if and only if we have virtue by nature. We must add the premise that we do not have virtue by nature in order to differentiate the capacities and virtue. Once Aristotle has shown that excellence is not a passion or capacity, he concludes that it must be a state.

Sample Paper on Aristotle's Nicomachean Ethics, Book 5

Objections to Aristotle's Argument in Nicomachean Ethics, Book 5