The Only Way

Hypothetical situation (used only for illustration):
During WWII, a message comes down from the top brass saying: to get to the other side of the Rhine, use the Ludendorff bridge. One group of officers contend that, based on this message, Ludendorff is the ONLY way to get to the other side (We'll call them group A). Others say, "Other ways may exist" (Group B).

Is group A committing a logical fallacy? If so, what kind?

It isn't logical to claim that just because the brass says use that bridge then that means it's the only way to get across. This is kind of ambiguous. Maybe A is arguing because their orders are to use the bridge in question then, being the grunts, the orders must be followed regardless of the reality of other ways to cross the Rhein. Maybe it actually is the only safe way as all others are controlled by the enemy. There doesn't seem to be enough information to call fallacy. If it weren't for the war then I'm sure this is jumping to conclusions fallacy. But I just learned the jumping to conclusion one because DrBo mentioned it last time I read a question..lol. The brass says use the bridge and A simply jumps to the conclusion that it is the only way. I guess it depends on what A means by "only".

I can't match any specific fallacy with this. I am not sure if this is an error in reasoning, or simply an error in communication. Would it have been better for the brass to say this was the "best" way or the "only" way to avoid confusion? Yes. If the penalty for trying another way is death, then perhaps assuming it is the "only" way might be the best bet, especially if we understand the ambiguity, but draw our conclusion based on the safest option (not the most logically clear). If the situation was more casual, such as a passenger telling a driver "Take Bleaker Street to get to the highway," then perhaps the assumption that Bleaker street was the only way is a little more problematic. As long as we are not claiming certainties (e.g., "it is certainly the only way") and playing the odds (e.g., "it's best to assume this is the only way") our reasoning is there to protect us.

Seems like hasty conclusion to me, no basis is given for deducing that the command to take route X is the only available route.

Would have to see in what context "ONLY" was used, if it was meant as the best way then I wouldn't charge any fallacy.

ONLY could have been used for rhetorical effect.

Sp Bo almost agreed with me...he just types better and thinks clearer and is smarter and more educated. Hey I didn't do that bad bad for leaving high school in 11 th grade, I could be stupider.

I set up the question's elements carefully. Note that the one giving the information is an authority figure. Also, he never says the Ludendorff bridge is the ONLY way. He just says, "to get to the other side, take that bridge." Isn't there some fallacy that says something like: you cannot affirm a negative from a positive? Or something to that effect? That's what I was trying to get at and my reason for asking the questions is that I wanted someone to help me identify or classify the type of fallacy group A is committing, if any.

In the military, an order that comes down the chain of command is, effectively, "the ONLY way" when it refers to troop movements, until subsequent action and actual conditions necessitate a change-- which might not be forthcoming. In that context, the contention of Officer Group A is correct. (I will not get into whether military correctness is logical.) Officer Group B appears to need some retraining.

"Ours not to reason why, ours but to do and die." --Tennyson, "The Charge of the Light Brigade"

Let me start by saying I know little about military protocol, such as whether or not a directive like the one from the top needs to be followed without question.

I looked at "jumping to conclusions," and it looks like it applies here. The actual response would depend a lot on the situation. If an enemy battalion is bearing down on the troops and the note "to cross the Rhine, take the Ludendorff bridge" came down, I hope the troops would waste no time in crossing the bridge. Now, if the troops are conveying a large amount of equipment, it would be a good use of time to do some scouting and see if there is a more efficient way to cross the bridge.

Of course, the response has absolutely nothing to do with whether or not the initial statement by officer group A is an example of the fallacy of "jumping to conclusions." I contend it is. Depending on the situation, jumping to a conclusion might be a good response, just not necessarily a logical one.

It seems difficult to interpret this military example. One would think that this is not the first type of communication from the “top brass”, so previous training and actions would come into play. My opinion is that this is essentially and order mainly because the brass would want to be aware of the movements of their troops. I would think it would be very messy for officers to choose their own way of crossing the Rhine as they would be strung out along it. Of course if there are situations on the ground that would prevent using the bridge or it would endanger troops than it becomes a different matter.