Sorry. Smoke Monster is NOT MIB. by IanG

Seems much more in character of this pretty "new" character to use slightly more eloquent means. Did he come across to you sitting on that beach as someone that goes start raving mad through the jungle, lifting up trees, and causing general unrest? If MIB is also the false Jacob, then there's evidence there of him using manipulation to further his goals.

Reasons why Smokey isn't MIB

- If Jacob can be killed by stabbing and fire, why can't MIB as the smoke monster be killed by having dynamite thrown down a hole with it? Barely seemed phased.
- MIB seems to work through manipulation (appearing in cabins, impersonations, taking over dead bodies), being a loud crashing smoke monster seems out of character.
- Why would water stop MIB? They use water to seal areas off from the smoke monster's Cerberus Vents. Seems simple enough to change to human form and swim.
- Smokey has been referred to many times by people and hieroglyphics as "protection" and "security system". Why would something as simple as a security system, which has a single job (to protect something) care about loopholes and people named Jacob?
- Why would a circle of ash or sonic fences stop a guy who can shift into whatever he wants?

My theory is that just as there is a temple, a statue, and a ridiculous source of energy on this island, there is a security system protecting it. MIB and Jacob are inhabitants just as the Losties are (see my theory on the sub-time loop here for more on that). It just seems to me that making MIB something that can take any form he wants but kills people using a form much akin to a bull in a china shop, well.... some would say that's just 'lazy writing'. (sup j&j!)