Condition 1,"cocked and locked". round in the chamber, hammer back, thumb safety activated. by far the safest way to carry a loaded 1911 with a round in the chamber! and the way the gun was designed to be carried.
To the less experienced it seems scary because the hammer is back and there is a light trigger pull. However for the gun to fire three things must happen.
1) The thumb safety must be de-activated.
2) The grip safety must be depressed
3) The trigger must be tripped. To make the weapon ready to fire, you draw the pistol, (A good grip de-activates the grip safety) acquire your target and with your strong hand, de-activate the thumb safety, pull the trigger. Most experienced shooters practice placing their strong hand thumb over the thumb safety so this action becomes a natural fluid part of the presentation.
For all three of those things to happen accidentally at the very same time something very strange must be going on in your pants and I'm quite certain the average person would notice.
In contrast, lets compare this to a striker fired weapon such as the Glock. The Glock virtually has no safety so only one thing must happen for the gun to fire accidentally. Something must trip the trigger(thus de-activating the safety)
A double action revolver has exactly the same chances of an accidental discharge.
Condition 2, Round in the chamber hammer down, resting on the firing pin, safety off (the hammer must be cocked to activate the safety). In other words there is nothing to prevent the firing pin from being forced into the primer of the cartridge. (this excludes those designs that incorporate a firing pin safety device such as the Colt series 80's and the Kimber series II's) In my opinion not a safe way to carry a gun. The most dangerous way to carry a 1911.
To bring the gun into action you must draw and cock the hammer. Presumably while something extremely stressful is going on. This isn't as easy as it would be with a single action revolver, most likely there is a beavertail grip safety in the way effectively destroying any chances of a proper presentation grip. (In other words there's a good chance your going to die with a loaded gun in your hand)
Condition 3, empty chamber, hammer down, safety off. Some say this is a good way to carry a 1911 but I disagree. It is better than condition 2 but still a bad choice. You must draw and rack the slide, effectively destroying any chance of a proper presentation from the holster. There are those that practice with and have specially designed holsters to enable them to push down on the back strap charging the weapon immediatly before presentation but then you are presenting a cocked and locked pistol with no safety! This will most likely sweep part of your own body and I pray to God you don't have your finger on the trigger before you get to your target! Especially under stress.
please note I do not intend to start the Glock/1911 war all over again I merely used it as one of two examples.