It is impossible to set a political philosophy on a firm foundation without deciding first what the point of living is. If you don't know, then you are worse than useless: you are dangerous. To be clear, politics is the art of government. How we are ruled can vary from one extreme--that of a single man or woman who holds us all in his or her power--to another, that of radical anarchy, where everyone governs themselves, which practically is only possible in conditions of very low population density or--theoretically--extremely developed moral sensibilities.
As I have set the problem down, the first existential problem is why you should continue living in the face of difficulty. It is possible to continue living out of habit, but I feel it is very difficult to live HAPPILY without an answer or answers to this that you find congenial. The second problem is, having determined to live, what you should do.
This first set of questions constitute what I call the Meaning system. Every culture has to have one, and for the culture to be coherent as such, the answers need to be shared generally, as interpreted in mildly different ways by different people. Religion, of course, is the paradigmatic Meaning system.
The second set of questions deals with what I call the Truth system. One need not have reasons for doing what one does--indeed, I would argue that virtually every way of living is largely contingent, and that the decision to assume an identity of any sort is more important than the reasoning--but it does help in social settings. How do we agree on what is worth doing, as a group? How do we agree on what is True? Science, of course, is the default answer in our modern world, where Religion was in the past.
Only then do we get to Politics, which deals with the acquisition and disposition of power. I perhaps need a better word than politics, since it comes to us from the Greek polis, and presumes relatively liberal conditions, which of course were not present in the time of the Pharoahs, nor in Maoist China.
Leftism, in many respects, is an answer to Atheism. Leftists seek to find in the collective what they find difficult or impossible to achieve on their own: shared meaning, purpose, shared truth. And it is in the SEEKING of a better world that they find these desirable shelters from what we might term the "Existential Wind". This is important, since for them the Messianic zeal which their committment to a better world provides for them is soteriological: it constitutes their salvation, as good as they expect to get.
For this reason, the idea that other people--the workers, minorities, the environment, colonized nations--might not need them is too horrific to contemplate. They sense that some struggle is needed for happiness in this world, but they have rejected the notions of moral improvement, since all morality resides in biology, not spirit. There is no spirit. Therefore, "improvement" as an individual is impossible; one must look to the species, implicitly, although many would not take the metaphor this far, consciously.
Thus what one gets is the strenuous advocacy of abstractions that impinge on real human lives. From moral and emotional necessity, action is separated from effect.
This is how totalitarianism is built. I want to be clear: Lenin was an actual human being. He got tired, he crapped, he collected mushrooms, he liked to play chess. His words, and the actions of others that flowed from his words, had very real effects on 100's of millions of people, in his own time, and indirectly down to our own time.
We find it difficult to grasp the scope of the suffering that he wrought, but we need to be clear it is what he intended, and he personally oversaw much of it. When the farmers were hiding food, he authorized torture to find it. When they were purging rural communities, he told his Cheka thugs to "get tougher men".
From small ideas are large ideas built. In the case of Leftism, the rejection of standing moral virtue entailed in the rejection of "bourgeois" tradition and morality means, practically, that you do what you are told, and it is right because you were told to do it. It is the logic of the "Vernichtungslagern".
This bon mot is actually stolen from Catholicism, which as Dostoevsky saw did share at times much in common with the darkness of Communism: "error has no rights".
Leftists never evolve their own beliefs systematically, but let me do it for them.
First, life has no inherent meaning. You are born as a biological being whose consciousness is an artifact of biochemical processes whose antecendants stretch back virtually to the beginning of the world. What you think, believe, do: all of these things are determined by your genetics. In large measure, you are a biological robot, programmed for procreation and survival.
You notice, though, as an individual, that the idea of helping others makes you feel good. In one moment you are depressed and listless, then you are on fire with enthusiasm to increase that feeling of being compassionate, and eager to join the fight.
You also feel good being surrounded by likeminded men and women, who are also fighting the good fight. All of you accept the primacy of science as the arbiter of truth, which means that you regard each and every reading of the oracle to be truth incarnate. If the truths vary, you hew to whichever one is most popular.
Politically, you see the power of numbers. You see the power of organization. You recognize, as an Initiate in the Cult of Science, that morality has no higher purpose than the preservation of the species, so morality can be adapted as needed to serve whatever purpose you have in mind.
Practically, as a part of a political group, you are told what to do, and the truths you are given are invariably offered by recognized Initiates, who are either popular experts, or Scientists.
And so you are set in motion. In the past, many such people were claimed as victims of various revolutions. Many rose high in the Parties, and won for themselves little feudal fiefdoms somewhere, complete with serfs and the ability to tax their crops.
But all of this is of a piece. It is a qualitative Gestalt, reached through a process of conscious or unconscious logic, operating on assumptions which for many are too painful to contemplate for too long.
Conservatism is simple. It looks to the past, and uses solutions of proven worth, such as Christianity. Individuals may want to improve the world, but they are not driven by any compulsive need to run from ideas they cannot abide, and cannot escape. Conservatism is stable for this reason. The individuals are stable, and conservative societies are stable.
Liberalism--true Liberalism--is based on the idea that since no final answer to the problems of meaning and truth can be found in this world, that all answers that do not trample on the rights of others are acceptable. It is a logical extension of the doctrine of Christian charity, and our success, as Liberals, has been in large measure due to the sincerity of our religiosity.