The current reality of world capitalism shows in an increasingly evident way - and at a scale already fully global - the essential contradiction of an economic system that at the same time drives the continuous scientific-technical development (with the robotization of production, intelligence artificial or big data) deploys regressive social dynamics by generating unemployment and job precariousness, social polarization and increasingly serious crises or imperial wars and environmental destruction. To respond to the main problems posed by humanity, and the impossibility of governing or reforming the blind logic of capital, which subordinates the whole of society to the ever-increasing demands for profitability and accumulation - threatening the very survival of society. humankind by the ecological collapse of the planet-, the real practical and urgent task to face - the least disconnected from the demands of the current situation - is to build global alternatives to the capitalist order that make possible the modern ideal of citizen self-government, with the social and rational control of the economic process, the only possibility of guiding the development of society towards democratically elected goals. In this perspective, the materials that make up this book evaluate the possibilities of socialism and the planning of the economy in the light of current scientific-technical capacities in the fields of information technology, telecommunications and artificial intelligence, and propose for the debate a democratically planned, viable and efficient socialist economy model. The first part of the book presents the fundamental ideas and principles that should characterize the functioning mechanism of a planned socialist economy, establishing a comparison with what happened in Soviet-type economies. The second part responds to the traditional objection raised by the defenders of the capitalist regime that in a planned economy - without market processes and competitive price formation - rational economic calculation is impossible, which would inevitably condemn socialism to inefficiency .