Yeah, up until a little while ago, I always pegged Jamie as an INTJ. Someone recently made a convincing argument that his attention to safety/tried-and-tested personal approach to problem solving were hallmark characteristics of Si.
My intj spouse is that way, sometimes. If he's presented with a new problem, he first runs everything through his database of tried-and-true solutions, then, if nothing comes up, he's thrilled to find a new way to attack it. He digs intuitive jumping. But, since efficiency is high on his priority list, the *fastest* way to get the job done is the trump card. It's quickest to go with something he's already seen work well.
The same can be said for safety. It's terribly inefficient (for future endeavors) to chop off one's fingers or lose an eye.
That said, you can talk him out of any of his standard approaches if you make a convincing argument. He'll try anything as long as it makes sense (which is why the show has so much spark, I think...it consists largely of: can ENTP Adam come up with a convincing enough argument for his ridiculously innovative/bizzare idea to win over Jaime?)
INTJs hang onto ideas for the sake of efficiency and success, but will toss them into the trash heap so fast it'll make your head spin, if you prove something else works better. They differ from Si in that they really lack stubborn holding of position, if you're clever enough to appeal to their logic.
