PhD student in Belgian Institute for Space Aeronomy (BIRA-IASB), working on airborne atmospheric research
Plays sometimes guitar, likes trekking, cross-country skiing and kayaking, learns scuba diving
So, Why Socialism? Here is an answer that even a physicist could understand:
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Production is carried on for profit, not for use. There is no provision that all those able and willing to work will always be in a position to find employment; an "army of unemployed" almost always exists. The worker is constantly in fear of losing his job. Since unemployed and poorly paid workers do not provide a profitable market, the production of consumers' goods is restricted, and great hardship is the consequence. Technological progress frequently results in more unemployment rather than in an easing of the burden of work for all. The profit motive, in conjunction with competition among capitalists, is responsible for an instability in the accumulation and utilization of capital which leads to increasingly severe depressions. Unlimited competition leads to a huge waste of labor, and to that crippling of the social consciousness of individuals which I mentioned before.
This crippling of individuals I consider the worst evil of capitalism. Our whole educational system suffers from this evil. An exaggerated competitive attitude is inculcated into the student, who is trained to worship acquisitive success as a preparation for his future career.
I am convinced there is only one way to eliminate these grave evils, namely through the establishment of a socialist economy, accompanied by an educational system which would be oriented toward social goals. In such an economy, the means of production are owned by society itself and are utilized in a planned fashion. A planned economy, which adjusts production to the needs of the community, would distribute the work to be done among all those able to work and would guarantee a livelihood to every man, woman, and child. The education of the individual, in addition to promoting his own innate abilities, would attempt to develop in him a sense of responsibility for his fellow-men in place of the glorification of power and success in our present society.
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Albert Einstein, Why Socialism?, Monthly Review, New York, May 1949
and How?
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Firstly: if production is to have the aim of securing for everyone a dignified life, plentiful food and providing other cultural means of existence, then the productivity of labour must be a great deal higher than it is now. The land must yield a far greater crop, the most advanced technology must be used in the factories, only the most productive coal and ore mines must be exploited, etc. It follows from this that socialisation will above all extend to the large enterprises in industry and agriculture. We do not need and do not want to dispossess the small farmer and craftsman eking out a living with a small plot of land or workshop. In time they will all come to us voluntarily and will recognise the merits of socialism as against private property.
Secondly: in order that everyone in society can enjoy prosperity, everybody must work. Only somebody who performs some useful work for the public at large, whether by hand or brain, can be entitled to receive from society the means for satisfying his needs. A life of leisure like most of the rich exploiters currently lead will come to an end. A general requirement to work for all who are able to do so, from which small children, the aged and sick are exempted, is a matter of course in a socialist economy. The public at large must provide forthwith for those unable to work - not like now with paltry alms but with generous provision, socialised child-raising, enjoyable care for the elderly, public health care for the sick, etc.
Thirdly, in accordance with same outlook, i.e. for the general well-being, one must sensibly manage and be economic with both the means of production and labour. The squandering that currently takes place wherever one goes must stop. Naturally, the entire war and munitions industries must be abolished since a socialist society does not need murder weapons and, instead, the valuable materials and human labour used in them must be employed for useful products. Luxury industries which make all kinds of frippery for the idle rich must also be abolished , along with personal servants. All the human labour tied up here will be found a more worthy and useful occupation.
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Rosa Luxembourg, The Socialisation of Society, Die junge Garde, Berlin, 4 December 1918

When?

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Keep in mind that, much sooner than later, great avenues will again be opened, through which will pass the free man, to construct a better society.
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Salvador Allende, Last Words, Santiago de Chile, 11 september 1973
About the opinions expressed here, I apply what another thinker born in Germany wrote about his own work :
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Every opinion based on scientific criticism I welcome. As to prejudices of so-called public opinion, to which I have never made concessions, now as aforetime the maxim of the great Florentine is mine:

"Segui il tuo corso, e lascia dir le genti."
[Follow your own course, and let people talk - paraphrased from Dante]
Karl Marx , Capital, Preface to the first german edition, London, July 1867
Workers of the World, Unite!