Well, it seems that even after five years people still aren't letting the idea that Ghost somehow miraculously survived being shot and immolated go, so I thought it was time to do a retread of my previous blog on the subject with more of an emphasis on exactly what happened from the point of view of someone who didn't fail GCSE Biology.
Part One: The Shot heard around the world
There's a bit of controversy surrounding this one, namely where exactly Shepherd was aiming when he pulled the trigger. The problem is an ambiguity caused by the camera angle, and people no-clipping out (with the usual problems of exposing developer cheats and shortcuts) have claimed that the model is aimed either at the head, chest or shoulder.
The solid evidence we have in this respect is the texture map on Ghost's model when his limp body is thrown into the ditch, showing a cluster of entry wounds to his thoracic region, mostly around his sternum.
However, let's examine each theory from a more scientific point of view, regardless of in-game evidence.
Theory One: BOOM! HEADSHOT!
This is probably the easiest way to explain Ghost's death: in a contest between the human skull and brain and the .44 Magnum round, the bullet wins.
Theory Two: Centre Mass
Again, the large number of major organs in the chest means that the shots there can reasonably prove death.
Theory Three: One to the shoulder, or "It's just a flesh-wound."
This theory is the one most commonly claimed to "prove" Ghost's survival, on the grounds that "a shot to the shoulder isn't fatal". This ignores a couple of basic facts of human biology and ballistic physics. First of all, there is no such thing as a "non-fatal" place to shoot someone, and even if there was, the shoulder most certainly is not it.
Putting a hole in the Subclavian artery is not a trivial matter, for a kickoff. In addition, this is what a .44 Magnum will do to something with the same properties of human flesh. Now imagine that taking place inside an actual human body.
Part Two: KILL IT WITH FIRE
This is the other big claim for how Ghost survived. "If you noclip he's not on fire / the petrol wasn't poured on him / he's wearing a fireproof vest!"
As I said before, noclipping exposes cheats and shortcuts the developers made to get the game out to deadline. As a result things seen while noclipping are not really an adequate representation of what goes on.
As for the idea that the petrol wasn't poured onto him, now you're ignoring basic fluid dynamics and we've jumped from Biology to Physics. Roach's body is not a sponge. It didn't magically absorb all the petrol; it would have pooled at the bottom of the ditch the two had been thrown into.
Lastly, we come to what is considered to be the holy grail of Ghost survival theories. The mythical "fireproof vest". Many have claimed the existence of this artefact, but none have been able to prove it. Supposedly Ghost complains about being made to wear said garment, but when pushed for a level and time that said line is uttered almost everyone goes silent on the matter.
However, let's ignore whether it exists or not and look at whether it would actually help. And the short answer to that is no. The long answer is that while a "fireproof vest" might stop him from getting burned where it covers, there is a lot that it doesn't; namely the head and limbs. In other words what you would be left with would be a relatively untouched torso while the rest of his body is burned down to the skeleton.
Part Three: Conclusion
The idea of Ghost's survival is probably one of the most contentious issues of character death I have personally encountered in gaming. And it confuses me. There is nothing to be gained from a story perspective from having Ghost survive; in fact as far as the next game in the series is concerned he apparently never even existed since no mention of him is made at any point whatsoever. And this is before we start to consider the fact that he doesn't actually serve much of a purpose in Modern Warfare 2 either.