When you think about it on a mathematical and a psychological level karma must exist. Psychologically we all maintain an approximate balance so that we cannot be too happy or too miserable in perpetuity. This can be seen in the difference between people who live in first world nations and those who live in third world nations. Those of us who are blessed to have computers and electric, houses to live in, etc have different things to feel bad about, we can have bad days, we can even feel suicidal. Those who live with none of these benefits, no house, no electric, no food, etc can have good days; they find their joy elsewhere. If someone who is in a 1st world country will kill themselves out of misery then they obviously feel worse than someone in a third world country who is not miserable enough to kill themselves. The result of this internal balance which draws our feelings and sensations back towards a central stable area will mean that anyone who takes advantage of others for their own gain will achieve nothing because their experience will always pull back towards that central average.
It is similar in action to the way a drug user will gradually feel less joy at using their drug and will always want more an more. There is never any way in which a person can have more than others on an internal experiential level on any lasting basis. In fact there is also no way that a person can maintain an average feeling of sensation unless they are mentally damaged in some way because their experience will always be fluctuating either side of the central average or else the highs will have no lows to contrast against in order to be able to recognise the difference in them.
This psychological tendency to always aim for balance works in tandem with the mathematical tendency for numbers to always balance out. If you roll a dice millions of times you will ultimately find that any particular number will have approximately the same chance as any other number coming up. Life may be more complex than a six sided die but the same principle will apply. Over time things will have a tendency to average out. You may have a number of good days but you will also have a number of bad days in how fate tends to treat you. One day you will find a penny and on another day you will lose a penny. If you work harder you will earn more but if you work less hard you will earn less.
Most of the time this principle is very easy to see in action. The outliers are the problem in this theory. Human experience could be represented on a bell curve where most experience will be in the centre of the bell curve and at the edges there will be a few who seem remarkably lucky or remarkably unlucky. I have already pointed out that these outliers will have their experience drawn to a central stable set of feelings so the appearance of good luck or bad luck is merely an appearance as it seems to those viewing their experience from outside. The homeless person has advantages in some manners and, believe it or not, the wealthy person also has disadvantages. For instance, when you can afford anything you want instantly, then where is the joy of anticipation? You move from one purchase to another experiencing a fraction of the joy any of those purchases would give one of us. Likewise, if you are cold and wet then the sheer pleasure you can feel from the occasions when you step into the warm and put on dry clothes are unimagineable to someone who has never had that experience. So once again we see the action of the psychological manifestation of karma combining with chance to always see that balance is achieved.
When it happens that someone seems to experience misery or joy for longer than seems natural then it is usually because they have imposed that upon themselves. Someone who has done something bad to another person will often feel guilty about it and that sensation of guilt will force them to judge themselves badly, while someone who has brought joy to others will go away with a warm feeling of having done the right thing. This has been proven in experiments where people were given money and told to go out and spend it. At the end of the day their feelings of happiness were compared to the beginning of the day and it was discovered that those who had helped others with the money felt far more happiness than those who had spent it on themselves. This is probably an evolutionary mechanism that is inbuilt by the mutual protection we gain from living in groups above the danger that individuals would have felt if living alone in the wild. This nature of cooperation and sharing would have greatly facilitated communal living and seen reciprocaton from others, which of course is a far more obvious manifestation of karma achieving balance between individuals.
The obvious exception to this would be sociopaths who feel little compulsion to help others due to their limited empathy. Hoever even sociopaths have been shown to have emotions, although on a greatly reduced level, so even they will be able to feel unhappiness or happiness in response to their actions. Additionally the greatly diminished state of their emotional level could be considered by those who have a typical experience of joy to be a punishment in itself. Plus the sociopath will often have had to have been through a horrific experience to damage their mind in that way so the loss of emotion is once again a way in which the psyche tries to achieve the central balance and withdraw from the extreme of the horror that they have already experienced.
In essence it ultimately becomes impossible for anyone to ever experience any joy over and above their fellow humans, no matter how much they take advantage of them, but similarly as karma dictates, noone is able to experience more misery than their fellow beings. Balance will always be achieved in the end.
However I am certain that everyone reading this will be uncertain about this conclusion. Everyone knows of somebody, or is somebody who has suffered a terrible life changing incident that has greatly reduced their overal happiness. There is certainly evidence that such circumstances can impact upon a person’s ability to feel happiness in their lives. Regardless of what conclusions you draw from this evidence there still may be a way for karma to redeem itself, but to do so the conversation must pass into areas that are somewhat more philosophical. In religion the problem is easily dealt with through reincarnation or the afterlife. There are certain harshnesses to the idea of hell and heaven but karma is more likely to be associated with reincarnation.
I am not going to step into discussion of contiuity from one life to another but I will propose that in the event of reincarnation, if it does indeed exist, we are unable to retain memories from previous lives. If we did then there would be little point in reincarnating in a form to learn the lessons of the previous life as we would simply continue where we left off. Given the lack of memory actual physical continuity is not necessary as much as a mathematical continuity. Indeed the essence of spiritual issues is their detachment from the physical. The question should therefore centre around how much spiritual existence resembles physical existence. All that would be needed for the corresponding and contrasting life to come into existence following the end of our own would be the laws of averages. To put it simplistically, if at one point a person has behaved heinously and must therefore be taught the error of his ways then a corresponding life must come into existence in which those lessons can be learnt, perhaps the life of a devout monk or the life of a beggar. As there is no memory from one life to another there is a missing continuity between the death of the one and the birth of the next. Additionally there is no physical continuity. There is a ‘spiritual’ continuity but what exactly does that mean?
Essentially, do we have individual souls? The answer according to many religious and philosophical beliefs is that ultimately we are all one. We all have god within us and we are seeking for reunification, etc, etc, etc. Unsatisfying though it might seem, the only continuity necessary appears to be that the death of one with the birth of the other must both be connected by being related by both being part of the same existence. Given the perceived nature of an all powerful god it is not even necessary that the two lives should exist consecutively. The nature of us all being one, means, that in the formless nature of a fluid universe, we can in our ‘spiritual’ aspect be experiencing two contrasting lives separately and simultaneously. Such is the nature of being part of a unified spiritual embodiment that is purported to have omnipotence. To give it any limitation in that regard or to insist it follows the laws of physics misunderstands the nature of omnipotence and the power it has to be governed by physical laws, yet simultaneously not governed. Naturally this falls a little outside the previous arguments I have made but considering karma is a theory that has always been considered to fall in line with the more esoteric ways of thinking it would probably be inappropriate not to cover some of the less conventional and scientific manners in which the concept could be described.
Naturally, if we need to rely on this final hypothesis, that can be difficult to come to terms with if we do not already believe in some kind of spiritual world already. The impossibility of seeing beyond death or before birth renders any concerns academic. The logic falls into place upon certain assumptions, but even if those assumptions prove to be false it makes little difference. Similarly to a legal fiction this is a fiction that explains an idea and process, but does so in such a way that is not verifiable by material means. Unfortunately this means that we have to rely on faith alone to accept this final argument as it is a faith based argument. The positive side is that it makes no difference whether we believe it or not, so the action of faith is to simply take it for granted in the same way as Pascal might wager.