If Kelvin was able to meet Desmond, how come Desmond hasn't met the Others, or the crash survivors?

If Desmond was so cool about running away from the hatch, why didn't he do it already, before spending three years straight down there?

Why is the "incident" not explained in Orientation instructions, that is the whole POINT of the Orientation.

1. Because 108 minutes to hit a button doesn't leave a lot of time for exploration Desmond stumbled onto Kelvin by accident. Maybe he was getting some fresh air.

2. Because he had finally found his replacements he knew that he couldn't hit the button unless he fixed the computer which he couldn't so it was high tail it out or wait to die either way he figured he was dead and if they fixed the computer he didn't want to be locked down there any longer. Now was as good a time as any to give that job away, he found the perfect applicants.

3. The incident wasn't the point of the orientation it was to show what was to be done by the inhabitants in the hatch.

1. Desmond probably didn't try to walk half way across the island since he had to be back to press the button in 108 minutes. If your obssessed with pressing execute, you start to think that if you leave and something happens to you, then the world ends and its your fault. SUddenly you don't want to leave, thus you become a hermit. If the others don't find him, he doesn't the others.
2. He thought the computer was fried and something was going to happen. Not knowing if the whole island or maybe just the lab would go up seems as good a reason as any to high tail it. If they do fix it, you have gotten rid of the job of pressing in the numbers. Win-Win in his opinion.
3.Orientation means to get you ready for your task. Explaining what the incident was doesn't necessarily need to be included to explain that you need to press a button every 108 minutes.

1. Because 108 minutes to hit a button doesn't leave a lot of time for exploration Desmond stumbled onto Kelvin by accident. Maybe he was getting some fresh air.

Desmond DID know they were up there, he heard them and shined the light on them at least twice. Why was Kelvin welcoming and Desmond not? Doesn't make sense.

2. Because he had finally found his replacements he knew that he couldn't hit the button unless he fixed the computer which he couldn't so it was high tail it out or wait to die either way he figured he was dead and if they fixed the computer he didn't want to be locked down there any longer. Now was as good a time as any to give that job away, he found the perfect applicants.

Again, two flaws. If he wanted replacements that desperately, he could have welcomed them or actively searched for them. He ran because it was an option, and if he thought it was an option, it was also an option before the computer malfunctioned.

3. The incident wasn't the point of the orientation it was to show what was to be done by the inhabitants in the hatch.

Without knowing its importance, it was more likely they would fail since it was just a job or a task.

If Kelvin was able to meet Desmond, how come Desmond hasn't met the Others, or the crash survivors?.

If Kelvin told him bad things about the "others" he may have been avoiding them. He didn't know about the crash, if I remember right. They were all "others" to him. But he also didn't hurt them, just in case they were his replacement.

If Desmond was so cool about running away from the hatch, why didn't he do it already, before spending three years straight down there?.

Poor Desmond was probably infected with Kelvin's sense of urgency and is no more stable, I think, thank Danielle. He ran this time because he figured it was all over but may not know how bad "the end " will be. Hey, it's worth a try. Natural instinct to run from danger.

It's one of my favorite scenes from "Colossus: The Forbin Project" is when the giant computer knows people are trying to disarm the nuclear warheads and sets them off. Men are on the tower with the missle but when the warning alarm goes off they try to run down all those steps in time. They couldn't have gotten away with a race car but they still ran. One General is sitting in the foreground and just stays where he is, dropping his cigarette. He knows better.

Why is the "incident" not explained in Orientation instructions, that is the whole POINT of the Orientation.

As others have mentioned, the orientation is to teach whoever what they have to do.

If it is a psychological experiment then not telling them and leaving the watcher with a deep forboding would help push them to do as told and not question their job.

As mentioned in the orientation film, BF Skinner is a behaviorist, therefore, this is more than likely a social experiment examining peoples behavior to controlled stimuli. Thus, not giving the workers a reason for their actions but putting pressure on them of saving the world.

Desmond is lying!! Has to be.

Njc---------------

what if 'the others' arent one single group? what if there are a few different groups of people on the island being tested and they are all warned about the 'others' on the island

Desmond does know far more than he is letting on, but I suspect he knows just more than the losties, probably a little more about the purpose of the stations. Perhaps that is why Calvin is no longer around any more, as he was told the truth and Desmond snapped, my own potential theory with no real backing.

After all there was a mention of partners. My own personal leaning is that Desmond is also some victim of circumstance just like the original Losties, but due to his rabid beliefs that his negligence could lead to world destruction, and the limited countdown time, this would preclude him from scouting out the island much.

So in summary; Desmond may know the truth, but I find it doubtful, and he is possibly thankful that Jack and crew have shown up so he can go off and do something nice with his remaining time on the island, as he thinks they will probably be the death of "the world" somehow.

Also I would say that Calvin knew the truth, he was a behavioural psychologist who knew the truth, so played Desmond, but then Desmond on meeting the other Losties, was less sure, and reacted defensively, but potentially with the knowledge that they are replacements for his post/Station. So he also played them to some degree.