(Spoiler) What are the possible explanations for Memento? Part 1 of 6...
There have been several threads about the possibilities and truth in Memento so I dug this out of the archives...
Part 1: Premises and Theories
Like all films and stories, interpretations of the filmmakers vision and intent can be discussed and debated. I have seen some films where people have debated a difference despite what the director says was his intent [for me: Blade Runner comes to mind: I disagree with what Scott says he intended to imply. I do not infer what he claims from the film, nor do I think it makes the most sense based on the film. But that is a separate story...]
For any explanation or theory, it is important to differentiate between what we see as facts and what the conjectures are. The conjectures we have are based on what we presume the facts are. Facts can be used to dispute the conjectures of other theories. Conjectures can not dispute the conjectures of other theories. Conjectures are interpretations, accepted facts are not interpretations. Facts should be the same for all.
Given a premise about a film, one can conclude certain things about it when examined in the context of the film. The conclusion ranks its probability from essentially negating it (it is impossible) to it is a certainty (it is the only possibility) and also everything in between.
If one just takes the character of Teddy, several premises can be made to illustrate the various levels on this range of probabilities. These are meant only to be possible examples, many other premises are possible (essentially an infinite number of them).
Impossible. The premise is negated by the film. A premise like: Teddy gave Lenny all his tattoos is clearly impossible since the film shows Lenny giving a tattoo to himself and also shows him getting one from Emma.
Improbable. The premise is not negated by the film, but the premise does not seem very likely based on the film. Teddy is Natalie's brother. There is nothing in the film that negates this, the closest thing is that Natalie seems to think that Lenny may be the "Teddy" that Jimmy went to meet. She may be lying about this to Lenny and only pretending to think he was Teddy or she may not realize Jimmy went to meet her brother. Not impossible, but it does not seem too likely.
Possible. There is nothing to negate the premise or make it improbable, but neither is there anything which suggests or even implies that it is true: Teddy is Emma's brother. It is more likely that Teddy has Emma for a sister than Natalie, since there is no indication one way or another that Emma could not be. Nowhere in the film, is it suggested that they are sibling however, which seems to make the speculation unlikely.
Suggested/hinted There is nothing in the film which explicitly indicates that this premise is true, but there is at least one thing mentioned in the film which seems to indicate that it is meant to be true. Teddy is the cop who asked Natalie about Lenny. Natalie never gives the name "Teddy" or even "Gammell", but she states a cop came into the bar looking for someone with memory problems. It could be a cop whom we never see in the film, it could be someone else entirely. They may not even be looking for Lenny. There are other possibilities, but the "suggestion" is that the man was Teddy claiming to be the cop.
Implied. In this instance there is something in the film which indicates the premise is more likely true: Teddy is the one talking to Lenny on the phone (when Lenny is not talking to Burt on the phone). The person on the phone is providing info to Lenny which will ultimately "setup" Jimmy Grantz (which we learn later Teddy is doing), the person gives Lenny a photo, which Teddy says later that he took. Lenny agrees to meet this person Teddy is there. The movie indicates that Lenny has a note with the name "Officer Gammell" on it, and we know that is Teddy's name.
Probable. These are premises that are not quite facts, but seem to be "acceptable" and presumed to be true by many people due to the evidence in the film. Teddy is a cop. Teddy says on multiple occasions he is a cop and he has a badge. Lenny is even shown to examine the badge (at the time believing that Teddy is not a cop) and he believes that the badge is real. This does not make it a fact, since Teddy could be lying, the badge may be fake and Lenny may not be able to tell it is a fake. We get no explicit confirmation about whether or not he is cop, but we also are shown nothing to negate it and multiple times it is suggested and thus seems indicated.
Facts. These are not really premises as all. We see these things occur, so we can tell that they are meant to be seen as objective facts. Lenny shot Teddy. We see Lenny shoot Teddy. This is a fact. We can not tell why he shoots Teddy, this requires conjecture, based on the other facts in the film. It is a fact that Teddy says that he is a cop, but him being a cop can not be claimed as a fact.
Now it is important to realize that theories can not be proven. One can demonstrate that a theory is consistent with the facts, but it does not prove that the theory is true, it does not make it a fact. One can only disprove theories, by showing how it does not fit the facts that are presented. And just because you have a valid theory does not negate a different theory. Many theories can be devised to explain the facts and the theories do not have to be consistent with one another.
In general, theories are first judged on how well they fit the data. Theories that better fit more of the facts and have smaller holes are typically judged better than those that leave more holes and explain less of the facts. Occam's Razor is generally used to decide between theories which explain the facts equally well. If 2 theories are equally good, the simpler one is chosen. [Note: that this does not imply that the simpler theory is always chosen for any complex theory. The more facts we have the more complex the theory. The theory must first explain the facts, that is the most important aspect. Simplifying comes later when trying to arrive at a "preferred theory"] Simplifying for the most part is finding a theory that has fewer unneccessary elements or speculations.
The Memento explanations generally fall into 3 main groups which seem to cover, I beleive, almost all of the possible explanations that have been proposed. There are slight variations and subgroups within these groups, but these are generally more subtle and some can arrive just from nit-picking differences in certain aspects.
In this series of posts, The major interpretations will be listed and some of the pros and cons will be discussed.
In the Part 2: The Presumption that what we see may just be a fantasy or someone's recollection...