Yes, Buddhists believe in the law of karmic cause and effect, or the law of karma, just as they believe the infallible, simple truth that after one eats, one’s hunger will be satisfied.
Most people question the certainty of the law of karma because they view things from the limited vantage point of the present life only. They see unfair karmic rewards and retribution in this life: some people endure hardship and do good deeds all their lives only to receive no reward, not even a good death! Others pervert justice for bribes and commit every injustice imaginable, but nevertheless live a life of ease through legal loopholes, enjoying good fortune and longevity.
However, the law of karma operates through the three times. Besides one’s current life, one has already passed through countless previous lives, and one will pass through countless lives in the future. This current life, compared with the continuous stream of lives from the past into the future, seems as short and miniscule as the duration of a spark produced by striking a stone. Karmic results, which take place in an order determined by the relative size and weight of karmic forces, can be carried over from the remote past to the present or into the distant future. Good or evil deeds in this life may not bear karmic fruit during this lifetime, and the happiness or suffering that one experiences may not be caused by actions performed in this life. Rather, karmic forces generated in previous lives cause the majority of this life’s tribulations. Likewise, the consequences of this life’s actions are more likely to be felt in future lives. If one understands that the law of karma operates in all the three times, one will feel more convinced and accepting of its truth.
Furthermore, the law of karma is not the same as fatalism or determinism, as many people wrongly imagine. Buddhists believe that, except for certain heavy, unchangeable karma, people can change karma from previous lives by their efforts in following lives. For example, if in previous lives someone acted in a way to cause himself to be poor in this life, he can still work hard and thereby change his financial situation in this life. In other words, causes from the past plus causes [behavior] in the present jointly determine results in the present. This is why the law of karma is not fatalism or determinism, but rather one hundred percent “endeavor-ism.” If Buddhism were to fall into the quagmire of fatalism or determinism, then the theory that sentient beings can attain enlightenment could no longer hold. If one’s fate has already been determined in previous lives, wouldn’t all good deeds in this life be done in vain?
We see that the law of karma does not deviate from the principle of conditioned arising. From causal seeds sown in previous lives to the fruits harvested in this life, many auxiliary factors play a role in determining the results. Examples of these auxiliary factors include one’s striving or sluggishness and one’s good or bad behavior in the present life. As an analogy, although sugar-water is basically sweet, if we add lemon or coffee to the glass, the taste will change.
In summary, the law of karma in Buddhism runs through all three times and thus links together the past, present, and future. In the present life, we receive the effects of karma done in previous lives. Our behavior in this life can develop into karmic seeds that sprout in future lives, or it can interact with previous karma to produce results in this life.
The principle of karmic cause and effect seems simple but really isn’t so. Buddhism is like that also: it appears simple, but it is actually a very sophisticated religion.