The other problem is that karma has long been used to rationalize racism, caste, economic oppression, birth handicaps, and so forth. Taken literally, karma justifies both the authority of political elites, who therefore must deserve their wealth and power, and the subordination of those who have neither. It provides the perfect theodicy: if there is an infallible cause-and-effect relationship between one's actions and one's fate, there is no need to work toward social justice, because it's already built into the moral fabric of the universe. In fact, if there is no undeserved suffering, there is really no evil that we need to struggle against. You were born crippled, or to a poor family? Well, who but you is responsible for that?
I remember reading about a Tibetan Buddhist teacher's reflections on the Holocaust in Nazi Germany during World War II: "What terrible karma all those Jews must have had..." And what awful things did the Tibetan people do to deserve the Chinese invasion of 1950 and its horrible aftermath? This kind of superstition, which blames the victims and rationalizes their horrific fate, is something we should no longer tolerate quietly. It is, I think it is safe to say, time for modern Buddhists to outgrow it and to accept one's social responsibility and find ways to address such injustices.
In the Kalama Sutta, sometimes called "the Buddhist charter of free inquiry," the Buddha emphasized the importance of intelligent, probing doubt. He said that we should not believe in something until we have established its truth for ourselves. This suggests that accepting karma and rebirth literally, without questioning what they really mean, simply because they have been part of the Buddhist tradition, may actually be unfaithful to the best of the tradition. This does not mean disparaging or dismissing Buddhist teachings about karma and rebirth. Rather, it highlights the need for contemporary Buddhism to question those teachings. Given what is now known about human psychology, including the social construction of the self, how might we today approach these teachings in a way that is consistent with our own sense of how the world works? Unless we can do so, their emancipatory power will for us remain unrealized.
Buddhist emphasis on impermanence reminds us that Hindu and Buddhist doctrines about karma and rebirth have a history, that they have evolved over time. Earlier Brahmanical teachings tended to understand karma mechanically and ritualistically. To perform a sacrifice in the proper fashion would invariably lead to the desired consequences. If those consequences were not forthcoming, then either there had been an error in procedure or the causal effects were delayed, perhaps until your next lifetime (hence implying reincarnation). The Buddha's spiritual revolution transformed this ritualistic approach to getting what you want out of life into a moral principle by focusing on cetana, "motivations, intentions." The Dhammapada, for example, begins by emphasizing the preeminent importance of our mental attitude:
Experiences are preceded by mind, led by mind, and produced by mind. If one speaks or acts with an impure mind, suffering follows even as the cart's wheel follows the hoof of the ox.
Experiences are preceded by mind, led by mind, and produced by mind. If one speaks or acts with a pure mind, happiness follows like a shadow that never departs.
To understand the Buddha's innovation, it is helpful to distinguish a moral act into three aspects: the results that I seek; the moral rule or regulation I am following (for example, a Buddhist precept or Christian commandment, and this also includes ritualistic procedures); and my mental attitude or motivation when I do something. Although these aspects cannot be separated from each other, we can emphasize one more than the others -- in fact, that is what we usually do. Not coincidentally, contemporary moral philosophy also has three main types of theories. Utilitarian theories focus on consequences, deontological theories focus on general principles such as the Ten Commandments, and virtue theories focus on one's character and motivations.
The Sanskrit term karma (kamma in Pali) literally means "action," which suggests the basic point that our actions have consequences -- more precisely, that our morally relevant actions have morally relevant consequences that extend beyond their immediate effects. In most popular understanding, the law of karma and rebirth is a way to get a handle on how the world will treat us in the future, which also -- more immediately -- implies that we must accept our own causal responsibility for whatever is happening to us now, as a consequence of what we must have done earlier. This overlooks the revolutionary significance of the Buddha's reinterpretation.