http://www.accesstoinsight.org/lib/authors/thanissaro/karma.htmlKarma is one of those words we don't translate. Its basic meaning is simple enough — action — but because of the weight the Buddha's teachings give to the role of action, the Sanskrit word karma packs in so many implications that the English word action can't carry all its luggage. This is why we've simply airlifted the original word into our vocabulary.
But when we try unpacking the connotations the word carries now that it has arrived in everyday usage, we find that most of its luggage has gotten mixed up in transit. In the eyes of most Americans, karma functions like fate — bad fate, at that: an inexplicable, unchangeable force coming out of our past, for which we are somehow vaguely responsible and powerless to fight. "I guess it's just my karma," I've heard people sigh when bad fortune strikes with such force that they see no alternative to resigned acceptance. The fatalism implicit in this statement is one reason why so many of us are repelled by the concept of karma, for it sounds like the kind of callous myth-making that can justify almost any kind of suffering or injustice in the status quo: "If he's poor, it's because of his karma." "If she's been raped, it's because of her karma." From this it seems a short step to saying that he or she deserves to suffer, and so doesn't deserve our help.
This misperception comes from the fact that the Buddhist concept of karma came to the West at the same time as non-Buddhist concepts, and so ended up with some of their luggage. Although many Asian concepts of karma are fatalistic, the early Buddhist concept was not fatalistic at all. In fact, if we look closely at early Buddhist ideas of karma, we'll find that they give even less importance to myths about the past than most modern Americans do.
For the early Buddhists, karma was non-linear and complex. Other Indian schools believed that karma operated in a simple straight line, with actions from the past influencing the present, and present actions influencing the future. As a result, they saw little room for free will. Buddhists, however, saw that karma acts in multiple feedback loops, with the present moment being shaped both by past and by present actions; present actions shape not only the future but also the present. Furthermore, present actions need not be determined by past actions. In other words, there is free will, although its range is somewhat dictated by the past. The nature of this freedom is symbolized in an image used by the early Buddhists: flowing water. Sometimes the flow from the past is so strong that little can be done except to stand fast, but there are also times when the flow is gentle enough to be diverted in almost any direction.