In scientology, life is broken up into eight areas. Each of these is called a dynamic.
In english, the word dynamic is defined:
1) Adj. - pertaining to or characterized by energy or effective action; vigorously active or forceful; energetic: the dynamic president of the firm.
2) Noun - a basic or dynamic force, esp. one that motivates, affects development or stability, etc.
Hubbard states in Dianetics the Modern Science of Mental Health that all life has a dynamic instinct toward "Survive!" So every action that someone takes can be traced back to a desire to survive in some way.
Now, there are some actions that seem contra-survival (against survival), such as someone throwing himself on a grenade. And this would be contrasurvival if you only looked at the concept of survive according to one's own survival.
So Hubbard broke up the areas of life and defined them in this way:
Dynamic 1 - Survival for self. Survival toward yourself. Doing things that help you surive.
Dynamic 2 - Survival of family. This is (was) broken down to Dynamic 2A survival toward sex and 2B survival toward the family unit.*
Dynamic 3 - Survival for groups. Survival toward groups - actions that help a group that you are involved in.
Dynamic 4 - Survival for mankind. Survival toward mankind as a whole, doing things that help all people that belong to your species.
Dynamic 5 - Survival for life. Survival toward life as a whole. Plants, animals, etc.
Dynamic 6 - Survival for physical universe. Survival toward all things that are physically extant. Books, cars, etc. Anything at all that is physical.
Dynamic 7 - Survival for spirits. Surival toward all things spiritual. You as a spiritual being, ghosts, spirits. Whatever.
Dynamic 8 - Survival for infinity. Survival toward a Supreme being, god, prime mover unmoved.
*Dynamic 2 has recently been defined by the Church of Scientology as survival toward creation. The family is a creative thing, trying to create the next generation, etc. Art is a creative force. And so forth. This is a source of great contention between orthodox Scientology (what the church expresses) and protestant Scientology (freezone, etc), traditionalists and others.
People who do not agree with the current church feel that the redefinition is indefensible and an alteration of monsterous proportions.
The reasoning behind such is given as later statements by L. Ron Hubbard which redefine it, where those that opt for a more traditional definition feel that later statements would only add to the original definition, not fundamentally change it.
The suspected reason (by those that are critical to the orthodox church) is that this alteration was the only way to justify changes in management's decision to effectively outlaw members of it's cloistered orders (Sea Organization) from having children, and at some levels from even marrying (marraige is required before sex in the Sea Organization).
So, all actions are considered to be found somewhere within this range of survival. Someone throwing himself on a grenade is abrogating his survival of self for survival of his comrades (3rd dynamic), survival of his family (2nd dynamic) and/or survival of mankind as a whole (4th dynamic).
Things are considered survival or non-survival based on the percentage of creation vs. destruction intrinsic to the action or decision. So, this decision might be considered survival if it helped more dynamics than it hurt.
Man is considered to be basically good.
Overts are considered to be actions which do more harm to more areas of life than help. Withholds are those overts which are then withheld from being discovered because the person feels that discovery will harm his survival. All overts are committed to solve some problem.
A problem is a force, counter-force; decision, counter-decision; one thing versus another which then sticks there in the middle. Problems are often based on opposition of dynamics in many cases. The urge toward survival of self vs groups as an example. If I go home, I will be better-rested, but if I stay here it will help my company.
So an overt is a solution which is short sighted or miscalculated and actually does more harm then good.
In Scientology, all upsets or desires to leave are thought to be because of overts and withholds, especially missed withholds. A missed withhold is a circumstance where someone "almost found out" or "might have found out" and so the person, to deflect attention from his own withholds will become upset or commit further overts to hide the original overt.
It is considered that when a person conciously or subconciously decides that he is committing too many overts, he will leave or will invite people to destroy him because this means that he will stop committing these overts which are against his basic nature which is good.