5 Skandhas

Who Am I?
When you think of yourself, you feel like a separate, permanent thing.  Actually "self" is a thing that is in five parts and constantly changing.  These changes happen many times a second and cause you to see things incorrectly, which in turn causes you to make bad decisions.  The five parts that make "you" are:

1. Your body and the sense organs. These create the next part . . .

2. Sensations. Pleasant, unpleasant, and neutral feelings.

3. Conceptualization.  This is where you turn your body's raw data into ideas.  Your delusion becomes evident here.   The raw data could be perceived in many different ways.  Your existing karma , prejudices and feelings filter the data and cause you to have incorrect perceptions.  For example, if you are angry and someone unrelated walks in, you will quickly find fault in them regardless of their behaviour.  This is why no one wants to see the boss when they are in a bad mood.  We know that whatever we show them will not be well received regardless of its value.  The process of avoiding the boss then, is an acknowledgement that we believe people's behaviour is sometime irrational because of their inability to see things objectively.  Buddhism merely extends this idea by saying we are always deluded, on some level, by desire, anger and ignorance, so our behaviour too is inappropriate.  A popular idea in psychology is that insane people's behaviour is usually correct from the point of view of the distorted world they perceive.  This is close to the Buddhist concept.

4. Will, mental acts, or mental formations. Volition, attention, discrimination, happiness, resolve, compulsion, concentration

5. Consciousness of self.

You exist.  Don't let anyone tell you don't.  Trendy philosophers sometimes like to say nothing is real or that they don't really exist.  If someone thinks they don't exist, ask them to hurt themselves, or give you all their money.  They won't do it because they know deep down that they are real. 

On the other hand, it's true that you don't exist in a meaningful, permanent, separate way.  It is like a wave.  When a wave travels across the ocean, it appears to be a separate, moving object.  Actually it is just energy making water bump the water next to it.  Most of the water in a wave traves only a few feet.  So you could say that a wave doesn't really exist, but there is merely an energy transfer happening.  On the other hand, this information won't help if you are surfing and get dumped.  You will truly believe in the wave when you wipe out.  So what Buddhism is saying is, you exist, you are just not as separate or consistent as you thought.

Western philosophy hangs a lot on the idea, "I think, therefore I am".
Zen however says: "I think I am, therefore I become."