Caesar Life of a Colossus by Adrian Goldsworthy is a great biography of Julius Caesar. In reading the book I came across this incident, which triggered some thoughts on problem solving facilitation.

Publius Considius was a tribune in the army of Julius Caesar, during Caesar's campaign against the Helvetii. The Helvetii were a warlike tribe living in Switzerland, much more oriented to pillaging other tribes than in developing their own agriculture. But with the relatively poor Swiss farmland, there were few other successful tribes that could be pillaged with much return, so their pillaging talents were really being wasted.

So they began a move to Gaul where there were lots of rich tribes with lots of possessions, so some really great opportunities to use their pillaging expertise. There were about 340,000 of them, so this was a pretty significant migration.
Caesar at the time was the Roman Administrator for Gaul, meaning he had to provide protection for the tribes there. (Who were of course paying significantly to Rome for this. The Italian and later Sicilian Protection Business was apparently, already thriving). So he had to do something about this large looming danger.

Caesar pursued the Helvetii with a very much smaller force, around 35,000. He located them and set up for a surprise attack on them. Titus Labienus, one of his generals, would take two legions during the night, and occupy some hills overlooking the camp of the Helvetii. Caesar would allow some time, then would approach directly with his main force of four legions, both groups then attacking at first light. (It was apparently OK given the difference in the size of the forces, to attack the camp of an unsuspecting enemy, even with all the women and children present.).
Labienus moved his legions out in the dark. Then sometime later, Caesar moved his legions out close to the Helvetii. He then sent out a scouting party under Considius, a supposedly experienced soldier, to verify that Labienus was in position.

Considius returned at a gallop and reported that the enemy were in possession of the hills, and there was no sign of Labienus. When questioned, Considius was emphatic that he had seen the banners and emblems of the enemy on top of the hills. Based on this information, Caesar had to assume that the enemy was somehow prepared for him. He cancelled his attack plan and took up a defensive position waiting to be attacked himself.
After waiting all day, the attack never came, so another scouting party was sent out. They found that indeed Labienus was in possession of the hilltops and had been there the whole time, waiting for Caesar’s attack signal. The Helvetii had been completely unaware of Caesar's presence and the attack opportunity had been missed. The Helvetii had since decamped and moved on.
The premise is that Considius, in the dark, thought that he had been discovered by the Helvetii and simply panicked and ran, but felt that it was important to be emphatic about the probable facts to not diminish Caesar's perception of him.
This incident was a great embarrassment to Caesar, and it is not reported what happened to Considius, although probably safe to assume nothing good. His action was well reported in Caesar's journals, where he was of course blamed for the entire fiasco.
A short time later Caesar's Legions did indeed defeat the Helvetii at the Battle of Bibracte (but with significant losses) and forced them to return to their homeland.
(Perhaps to become the eventual founders of the Swiss Banking Industry. If you can't pillage violently, there are other ways).

So when I first read this, I thought, you know, I remember “S.O.Bs” just like Considius (even their names) in discussions over the years. In defining some problem issue there were some facts in question, but they were so emphatic about the correctness of their version of the facts, that the rest of us who had some doubt about our versions, felt that, well, they must be right.
Later on, it turned out that their facts were indeed wrong, and we had made a wrong decision because of that. Sometimes they fessed up and apologized. But there were some who were simply incapable of admitting that they could have been wrong. Even with the facts in front of them. There were extenuating circumstances, or someone had reported facts incorrectly to them. But they had definitely not been incorrect in what they said, based on what they knew at the time.
This would always drop them a notch, or so, in my, and some others', regard for them. But many times, they still moved on and up in the organization. Their absolute, total confidence in what they said was apparently viewed as a sign of strength by those whose opinions really mattered.

For some, it seems that virtually everything is a contest, and always winning is really important to them, perhaps simply to preserve their own perceptions of themselves, and their perception of what others will think of, and value in them.

The best known winning golfers of all time are Jack Nicklaus and Tiger Woods. Both had prodigious physical talent, but so do many others. Their real strength, why they won so often, is said to be in the toughness of their mental game. They had tremendous focus and confidence in what they could do. If you had something really, really important riding on a putt, you would want one of these two making that putt. Either one of them, in preference to someone more renowned just for putting excellence.
Jack Nicklaus is known to have insisted that he had never missed a short putt to win a tournament. He had simply put any of his misses completely out of his memory to maintain the confidence that was the key to his success.

A famous Henry Ford quote, "If you think you can, or if you think you can't, you're probably right."

But you know, Considius like behavior is insidious in all of us, (sorry, couldn't resist). Problem-solving facilitators need to be very aware of this apparent human tendency to evaluate ourselves and others based on whether our knowledge seems to be rock solid or not.

I've struggled with this in facilitating problem-solving sessions when someone takes an absolutely emphatic position on facts that seem questionable. Of course we have to poke at these facts just like any other facts to verify them. We expect people to come to the meeting with as many verified facts as possible, not just loose, undefined observations or suppositions. Continually emphasizing the verifiability of facts is an important part of constantly teaching the process.

But it’s important to do this in a way that doesn’t trigger them into defensive behavior. Facilitators have to avoid the aggressive, attorney, questioning behavior that we’ll see on TV shows. Problem solving sessions are above all a cooperative effort to properly define an issue, find solutions to it, and in doing this; more importantly, continually develop cooperative, problem solving capability in the workforce. This is the spirit that we need to maintain at all times.
Too often facilitators (and other group members) will aggressively challenge facts without regard for the feelings of the individual presenting them. And with some individuals, it seems like it's almost a plus if they can be embarrassed in front of the group .
Of course, doing that, really knocks back their participation for the rest of the session. Their participation, but also the participation of others, with some uncertain facts, who will also now worry about being embarrassed in front of the group if they present them. The whole cooperative tone, and the effectiveness of the meeting, can be lost.

Facilitators can’t let this happen. They have to keep the discussions positive, cooperative, and civil at all times. Getting the best facts possible, and verifying uncertain facts, is essential to the problem-solving process.

So it’s really important to create an environment where individuals can state facts without feeling that they're in some kind of contest. If there is some uncertainty to the evidence that someone is offering, then they need to be comfortable stating this. Facilitators need to make clear that it's not any reflection on the character or capability of a person if they are not emphatically sure of what they're offering. Having to do some more work to verify facts isn’t the end of the world, in fact, flushing out the detail of facts is a part of the process, and showing the necessity of having to do this is a part of the teaching process.

Good facilitators can question the substance behind facts without forcing someone to become defensive and driving them to stating unwarranted certainty. (And they make sure that others in the session don't force that either).