AtulaSiriwardane said:
Karma... hmmm... good topic!!! 
Source:
http://www.buddhanet.net/e-learning/karma.htm
What is Karma?
The Pali term Karma literally means action or doing. Any kind of intentional action whether mental, verbal, or physical, is regarded as Karma. It covers all that is included in the phrase "thought, word and deed". Generally speaking, all good and bad action constitutes Karma. In its ultimate sense Karma means all moral and immoral volition. Involuntary, unintentional or unconscious actions, though technically deeds, do not constitute Karma, because volition, the most important factor in determining Karma, is absent.
The Buddha says:
"I declare, O Bhikkhus, that volition is Karma. Having willed one acts by body, speech, and thought." (Anguttara Nikaya)
Every volitional action of individuals, save those of Buddhas and Arahants, is called Karma. The exception made in their case is because they are delivered from both good and evil; they have eradicated ignorance and craving, the roots of Karma.
"Destroyed are their germinal seeds (Khina bija); selfish desires no longer grow," states the Ratana Sutta of Sutta nipata.
This does not mean that the Buddha and Arahantas are passive. They are tirelessly active in working for the real well being and happiness of all. Their deeds ordinarily accepted as good or moral, lack creative power as regards themselves. Understanding things as they truly are, they have finally shattered their cosmic fetters – the chain of cause and effect.
Karma does not necessarily mean past actions. It embraces both past and present deeds. Hence in one sense, we are the result of what we were; we will be the result of what we are. In another sense, it should be added, we are not totally the result of what we were; we will not absolutely be the result of what we are. The present is no doubt the offspring of the past and is the present of the future, but the present is not always a true index of either the past or the future; so complex is the working of Karma.
It is this doctrine of Karma that the mother teaches her child when she says "Be good and you will be happy and we will love you; but if you are bad, you will be unhappy and we will not love you." In short, Karma is the law of cause and effect in the ethical realm.
Karma and Vipaka
Karma is action, and Vipaka, fruit or result, is its reaction.
Just as every object is accompanied by a shadow, even so every volitional activity is inevitably accompanied by its due effect. Karma is like potential seed: Vipaka could be likened to the fruit arising from the tree – the effect or result. Anisamsa and Adinaya are the leaves, flowers and so forth that correspond to external differences such as health, sickness and poverty – these are inevitable consequences, which happen at the same time. Strictly speaking, both Karma and Vipaka pertain to the mind.
As Karma may be good or bad, so may Vipaka, - the fruit – is good or bad. As Karma is mental so Vipaka is mental (of the mind). It is experienced as happiness, bliss, unhappiness or misery, according to the nature of the Karma seed. Anisamsa are the concomitant advantages – material things such as prosperity, health and longevity. When Vipaka’s concomitant material things are disadvantageous, they are known as Adinaya, full of wretchedness, and appear as poverty, ugliness, disease, short life-span and so forth.
As we sow, we reap somewhere and sometime, in his life or in a future birth. What we reap today is what we have sown either in the present or in the past.
The Samyutta Nikaya states:
"According to the seed that’s sown,
So is the fruit you reap there from,
Doer of good will gather good,
Doer of evil, evil reaps,
Down is the seed and thou shalt taste
The fruit thereof."
Karma is a law in itself, which operates in its own field without the intervention of any external, independent ruling agency.
Happiness and misery, which are the common lot of humanity, are the inevitable effects of causes. From a Buddhist point of view, they are not rewards and punishments, assigned by a supernatural, omniscient ruling power to a soul that has done good or evil. Theists, who attempt to explain everything in this and temporal life and in the eternal future life, ignoring a past, believe in a ‘postmortem’ justice, and may regard present happiness and misery as blessings and curses conferred on His creation by an omniscient and omnipotent Divine Ruler who sits in heaven above controlling the destinies of the human race. Buddhism, which emphatically denies such an Almighty, All merciful God-Creator and an arbitrarily created immortal soul, believes in natural law and justice which cannot be suspended by either an Almighty God or an All-compassionate Buddha. According to this natural law, acts bear their own rewards and punishments to the individual doer whether human justice finds out or not.
There are some who criticise thus: "So, you Buddhists, too, administer capitalistic opium to the people, saying: "You are born poor in this life on account of your past evil karma. He is born rich on account of his good Karma. So, be satisfied with your humble lot; but do good to be rich in your next life. You are being oppressed now because of your past evil Karma. There is your destiny. Be humble and bear your sufferings patiently. Do good now. You can be certain of a better and happier life after death."
The Buddhist doctrine of Karma does not expound such ridiculous fatalistic views. Nor does it vindicate a postmortem justice. The All-Merciful Buddha, who had no ulterior selfish motives, did not teach this law of Karma to protect the rich and comfort the poor by promising illusory happiness in an after-life.
While we are born to a state created by ourselves, yet by our own self-directed efforts there is every possibility for us to create new, favourable environments even here and now. Not only individually, but also, collectively, we are at liberty to create fresh Karma that leads either towards our progress or downfall in this very life.
According to the Buddhist doctrine of Karma, one is not always compelled by an ‘iron necessity’, for Karma is neither fate, nor predestination imposed upon us by some mysterious unknown power to which we must helplessly submit ourselves. It is one’s own doing reacting on oneself, and so one has the possibility to divert the course of one’s Karma to some extent. How far one diverts it depends on oneself.
Is one bound to reap all that one has sown in just proportion?
The Buddha provides an answer:
"If anyone says that a man or woman must reap in this life according to his present deeds, in that case there is no religious life, nor is an opportunity afforded for the entire extinction of sorrow. But if anyone says that what a man or woman reaps in this and future lives accords with his or her deeds present and past, in that case there is a religious life, and an opportunity is afforded for the entire extinction of a sorrow." (Anguttara Nikaya)
Although it is stated in the Dhammapada that "not in the sky, nor in mid-ocean, or entering a mountain cave is found that place on earth where one may escape from (the consequences of) an evil deed", yet one is not bound to pay all the past arrears of one’s Karma. If such were the case emancipation would be impossibility. Eternal recurrence would be the unfortunate result.
What is the cause of Karma?
Ignorance (avijja), or not knowing things as they truly are, is the chief cause of Karma. Dependent on ignorance arise activities (avijja paccaya samkhara) states the Buddha in the Paticca Samuppada (Dependent Origination).
Associated with ignorance is the ally craving (tanha), the other root of Karma. Evil actions are conditioned by these two causes. All good deeds of a worldling (putthujana), though associated with the three wholesome roots of generosity (alobha), goodwill (adosa) and knowledge (amoha), are nevertheless regarded as Karma because the two roots of ignorance and craving are dormant in him. The moral types of Supramundane Path Consciousness (magga citta) are not regarded as Karma because they tend to eradicate the two root causes.
Who is the doer of Karma?
Who reaps the fruit of Karma?
Does Karma mould a soul?
In answering these subtle questions, the Venerable Buddhaghosa writes in the Visuddhi Magga:
"No doer is there who does the deed;
Nor is there one who feels the fruit;
Constituent parts alone roll on;
This indeed! Is right discernment."
For instance, the table we see is apparent reality. In an ultimate sense the so-called table consists of forces and qualities.
For ordinary purposes a scientist would use the term water, but in the laboratory he would say H 2 0.
In this same way, for conventional purposes, such terms as man, woman, being, self, and so forth are used. The so-called fleeting forms consist of psychophysical phenomena, which are constantly changing not remaining the same for two consecutive moments.
Buddhists, therefore, do not believe in an unchanging entity, in an actor apart from action, in a perceiver apart from perception, in a conscious subject behind consciousness.
Who then, is the doer of Karma? Who experiences the effect?
Volition, or Will (tetana), is itself the doer, Feeling (vedana) is itself the reaper of the fruits of actions. Apart from these pure mental states (suddhadhamma) there is no-one to sow and no-one to reap.
