Imagine you are dead, in which case the biological machinery that you once relied so much on is no longer functioning. Due to the conversation of energy and mass, the atoms made up this biological system won’t just miraculously vanish. Theses atoms would remain pretty much the same, unless nuclear reaction or annihilation occurs (though there’d be changes in the configuration of electrons in the process of decomposition). At this point in time, it would be silly to still consider these atoms “you”.

But what are actually “you”? How should “you” be defined?

To people around you, you are a concept they conceived in their mind based on their interaction with the being labeled “you”, and the information they have about this being. To them, you are a construct of their own ideology. This version of you sometimes reflects the rose colored lenses through which they perceive the world a lot more than how it would reflect anything about the being labeled “you”.

To you, you are what that constitutes the idea of self. Apparently you possess a body, but the body is not what you identify you with when you think about you. You may incline to think that you are what that controls the body, makes decision, etc, that is, the mind. But let’s for a moment remember that the brain is responsible for the construction of thoughts and it governs how the mind processes, similar to how the computation performed by a Turing machine is governed by its transition function in relation to its states. So a question arises:

What determines you to be the mind A that's constructed by brain A, instead of the mind B constructed by brain B, where A ≠ B?

I shall now present to you the Theory of The Observer.

Suppose a mind is definable.

For every mind, there exists an observer that does nothing besides observing the mind. An observer is not a being, it exists outside the context of the universe which the brain that constructs the mind is a part of. The observer of a mind is incapable of doing anything to the mind, as all it does is a one-way observing: a one-direction transfer of data (similiar to that of a GET request by the W3C specification). As far as an observer is concerned, other observers don’t exist, because in the context of the observer, the only thing that exists is the mind.

Here I’m taking more of an information approach to the concept of existence. In the context of system A, X does not exist as long as

  1. the information in/about system A relies nothing on the information about X, or any information X contains
  2. any changes in the information about and in X has no impact on any information in/about system A

Under this definition, the answer to the old philosophical “if a tree falls in a forest and no one is around to hear it, does it make a sound?” would be that both the tree and the sound don’t exist in the context of system A if and only if the two points above are satisfied.

For the sake of argument, if the observer of mind A were to be switched over with another observer that is observing mind B, it would have no effect on the minds or affect any event in the universe wherein the minds are.

The Theory of The Observer can be stated as follow: You are the observer. You are experiencing person A’s life because you are observing some aspect of the computation happening in person A’s brain (which is the mind). If making decisions with free will is defined as selecting a choice in a set of possible choices based on some data, from the point of view of person A’s brain, that is preciously what the computation does. However, from the point of view of the observer, there exists no freedom of choice since everything about the computation at time T is already determined by the previous states of the brain and what were inputted, all happening before time T.

Here is an example. Person X murdered Person Y at time T. Person X did it as a result of a set of factors F happened before time T. The same set of factors F will not cause Person Z to murder Person Y, but it caused Person X to murder Person Y. That may be explained by the environment Person X grew up in and may also have to do with genetics. So one way of looking at this is that Person X shouldn’t be blamed because if we connect the dots together, we’d realize that Person X did not really have had a “choice” to become the person she/he became. But another way of looking at this is that, Person X’s brain is a computational device that selected the choice of murdering Person Y and executes it at time T so we should lock Person X up.

But by definition, observer contributes nothing whatsoever to the computation of the brain. So every thought in the mind is a product of the brain. That is to say, when you think you are engaging in the activity of thinking, you are obviously not, for you are the observer and the observer does not think (or engage in any activity apart from observing). However, everything happening in the mind is being observed by the observer, and for that reason, it is as if you, the observer, are thinking. And since the Theory of The Observer is also a product of the mind, it is not guaranteed to capture the true nature of the observer, and the observer would not have anything to do with this theory, because after all, the observer should not have any effect on the mind which the observer is observing.

Thus you are, after all, the mind, observed by you, the observer which does not exist in the context of the universe wherein the computational machine (i.e. the brain) is, similar to how you, the mind, will cease to exist, after the computational machine no longer functions, in the context of the same universe.