fate (n) - the tendency of reality to follow a seemingly pre-determined path; often accompanied by the statement "everything happens for a reason".
The concept of fate seems, at first to be complete unrelated and unimportant to philosophy. It is more often used in the context of infatuated teenagers that state that they were brought together by a supernatural sense of destiny that wanted nothing more than to see them together. However, upon further examination, the idea of fate is central to many philosophical questions:
Nature vs. Nurture
This debate has a very simple basis - the question of whether or not a person's human characteristics are more (or entirely) attributable to one's chemical / genetic make-up or the manner in which that person was raised. However, these two theories (or amalgamations thereof) unite on the assumption that personality traits and physical characteristics do not allow for variations in decision of the person whose human nature is in question (person x, for the sake of discussion). While person x does have the ability to make decisions, the decisions that he or she will make is directly output of only his or her environment or genetics. The Nurture theory takes into account the decisions a parent makes, however, those decisions are again directly determined by person x's grandparents and so forth. Adversely, Nature takes into account the decision of whom with which to mate, which is again a direct output of person x's parents' genetics. Here is the concept of fate in both these theories: what you are is because of the situations surrounding your creation. What you are is what you were logically (or supernaturally) meant to be.
Behaviorism / Freudian Psychology vs. Humanism
The origin of personality, while discussed in Nature vs. Nurture theories, is more deeply pondered in the three leading personality theories. Behaviorism (considered to be fathered by B. F. Skinner) and Freudian Psychology both fall under the Nature vs. Nurture category in that they don't consider it possible for random changes in personality based on self decisions. In other words, both do not include the concept of free will in their theories. Humanism, being much more idealistic, depends on two principles: Humankind is basically good and every individual is endowed with free will. Differently from the last theory, fate is the point of seperation in these ideologies. B. F. Skinner and Freud would say that fate is the only logical approach to personality while the Humanism school of thought would say that fate holds no bounds on our futures as an individual.
Evolution vs. Intelligent Design & The Big Bang or Inflation Theories vs. Creationism
The classic battle of religion against science also centers around fate.
If we are to believe the scientific theories as they are stated as well as the concept of fate, we can follow this logical path: If everything happens for a reason, everything has a cause. The cause of everything must also have a cause. Therefore, everything that has happened, is happening, and will happen, is caused by the first event. This leads to the belief that the entire course of history in the universe was held in the nearly-infitessimal point of matter at time 0. On the other hand, Intelligent Design/Creationism as it applies to fate results in a paradox - how can one have God-given free will if everything that happens (including everything an individual does) for a reason? If an individual choses to do something senseless or extremely damaging, it does not seem to fit under the concept of fate.
The final point - Is anything random?
Randomness is the state of being wholly unpredictable or having no pattern whatsoever. This idea is wholly scary to some - the idea that there are things that don't have rhyme or reason. But in all our humanly power, mankind has been unable to generate something as simple as a random number. Computer random number generators are based on events or numbers that are very hard to predict, such as the millisecond that the random number is asked for. However, this quantity is not random.
Belief in fate requires a certain amount of faith. But, it seems, not believing in fate does as well. As long as man can't find anything truly random, it is impossible to say for sure that fate does or does not exist. It's a point to ponder.