Karma is one of the most evasive doctrines in Buddhism (and throughout Indian religion/philosophy). Here is a typical statement on karma/kamma…
You want: long life, health, beauty, power, riches, high birth, wisdom? Or even some of these things? They do not appear by chance. It is not someone’s luck that they are healthy, or another’s lack of it that he is stupid. Though it may not be clear to us now, all such inequalities among human beings (and all sorts of beings) come about because of the kamma they have made individually.
(by Bhikkhu Khantipalo) from the introduction to the Cula-Kammavibhanga Sutta.
The key question I have is about HOW karma works. My starting point tends to be in the 5-niyama doctrine:
Crucial here are the five Abhidhamma modes of causality : (1) physical-organic (uti-niyama); (2) biological (bija-niyama); (3) non-volitional mental (mano- or citta-niyama); (4) volitional mental (kamma- or karma-niyama); and (5) – and the most unclear and problematic – spiritual (dhamma- or dharma-niyama).
I just delight in impressing people by saying, “utu, bija, citta, kamma, dhamma.” It has a nice sound.
We have dhamma on the one side, the abstract totality or truth of reality. One of my early teachers, Alan Sponberg, gave us the image of the dharma as the vibration of the universe and each of us just being a bit out of tune. If when we become attuned, we live in harmony with reality, awakened.
On the other side we have citta (pronounced chit-ta), the activity of the mind. The mind has all sorts of wonderful attributes, but it is also the source of the erroneous mental construct of ‘self’ and ego. It seems then that the Buddhist path is meant to move us from a life dominated by citta to one in tune with dhamma. In the midst of this path is kamma.
The pitfall that my current advisor, Damien Keown, points to is a sort of psychological reductionism. If kamma is just reduced to mental states such as greed or motivations then the dhamma aspect can be lost. For instance, anything might be morally acceptable if it comes from a positive motivation. For example, lying – it may be thought to give good karma to lie if it helps people. However, in Buddhism it is said that the Buddha never lied, and that an awakened being in fact cannot lie.
This, I suppose, is because a lie violates the harmony of the Universe, the dharma.