If Smith's brain gets transplanted into Jones' body, then it may be said that Jones is not the same person he was before. However, Smith's brain brings along with it all of the ``inside'' information about Smith's ``previous'' life. One would tend to agree that because Smith can remember so much personal and inside information about Smith's old body, that his consciousness indeed resides in Jones' body.
Arguments against the memory theory reside in discontinuities over time slices. If someone is 20 years old, and can remember what happened to him at ten years old, and the same person at 40 can remember his 20's, but not events which occurred when he was ten, then the memory theory fails. In this case, the person at 40 is not the same person he was at ten years old. Shoemaker argues that this failure to reconcile the differences comes from the word play of able to remember, versus actually remembering. Under hypnosis, the person at forty will remember events of his early childhood. Locke states that the person is able to remember, if he wanted to, the memories he has forgotten. Consider the many times you have attempted to remember where you have placed a particular item. Sometimes you completely cannot remember where you have placed your item. However, its location would be revealed easily when you sit down, and think about the course of events leading up to the last time you ``remember'' having your item. Then instantly, an image of the item's placement (and location) comes to your mind. In this previous case, you were physically able to remember the location of the item; whether or not you do indeed remember is another matter altogether different.