Comments: I find this argument amusing. On the one hand, it’s relatively easy to get a handle on the reasoning in this one. On the other, that reasoning has been rather unimportant for purposes of public debate. Simply put, the implication that Chris Kyle is a coward has pretty ensured that subsequent dialogue would focus on affect display. In this discussion, it has been anger all the way down, so to speak.
Statements: The basic claims made in the argument are presented in bold below. Rewritten sections are in square brackets, and one missing conclusion has been added (statement 6).
 My uncle killed by sniper in WW2.
 We were taught snipers were cowards.
 [They w]ill shoot u in the back.
 Snipers aren’t heroes.
 Invaders [are] worse.
[] [Chris Kyle is not a hero.]
Discussion: This argument presents us with the following issues: Interactional Eclipse, Micro-Reasoning, and Missing Assertions.
Interactional Eclipse: Michael Moore may have good reasons for implying that Chris Kyle is a coward, but doing so has led respondents to focus on personal outrage at the expense of considering his argument. This may or may not have been Moore’s intent, but it was probably a predictable outcome of the tweet. Any effort to clarify the point or drive it home with an elaborate argument would not fit into the 140 character maximum allowed in a single tweet. So, the end result was a message that did more to rouse anger than it did to set the stage for a thoughtful discussion. Again, that may well have been the intent.
Micro-Reasoning: Moore actually got several specific claims into this tiny argument, but he did not spell out his actual conclusion and if there is any nuance to his thoughts about the courage or cowardice of a sniper, it didn’t make it into the text. Ultimately, this argument suffers from the extreme brevity of the format.
Missing Assertions: Moore relies on us to piece together his conclusions. It seems obvious, but he does not state it.
Diagram: Okay, so Moore first uses the argument from personal history to suggest that snipers are not generally heroes (1+2 -> 4). He then adds a specific reason for believing that Sniper’s are not heroes (3->4). This general argument implies that Kyle is not a hero. Statement 5 is then used to add an additional argument to the effect that Kyle (a member of an invading military force) cannot be a hero regardless of his specific role in combat.
Evaluation: Let me just focus on the inferences here. I’m not even going to comment on the truth value of the premises.
The inference from 1 and 2 to 3 is deceptive. Moore invokes personal experience to shore up his argument. that personal experience is of course with a family history and folk wisdom about the nature of snipers. Granting that Moore is reading these traditions right, this does not give a clear reason to believe that Snipers in general are not heroes. Those who have actually seen real combat may find it a little too ironic to see that Moore would invoke personal history on the subject. He isn’t claiming more than he could fairly put forward he is asking others to weigh that over the character of people with more personal experience than his. It’s a serious credibility problem. I would suggest that this inference is weak.
The inference from 3 to 4 is a little more interesting. This of course suggests that snipers use tactics enabling them to avoid danger. This may be true, but of course that doesn’t mean they do not face danger anyway, and of course people don’t usually win wars by making it easier for their enemies to kill them. Again, the inference is weak.
The inference from 4 to 6 is Strong to Deductively Valid. If no snipers are heroes then Kyle is by definition not a hero and the inference is D.V. If Moore is just saying that no snipers are heroes by virtue of being sniper, then it is at least possible that Kyle is still a hero, but the premise does take away the central claim for making him one. Hence, the inference would be strong.
It’s tough to measure the inference from 5 to 6. I would say it’s probably the same as that from 4 to 6 for similar reasons. So, the inference is Strong to D.V.
Final Thoughts: Some folks may not believe in heroes. Alternatively, some may regard heroism as a social construction having less to do with people’s actual behavior than with the way others see them and the stories that others tell about them. That is of course NOT Moore’s argument here. He gives us no reason to believe that he doesn’t acknowledge heroism in some contexts, so a general cynicism regarding the prospect of heroism would not help his argument. It might however have provided an interesting argument in its own right.
Some folks might also argue that details of Kyle’s actual behavior, and some of the stories he has told since leaving service are deeply disturbing without suggesting that he is a coward. Simply put, Kyle can be a a lot of bad things and also be courageous too. Which should matter more is an interesting question, but that too is NOT the argument presented in this tweet.