Participatory action research investigates the living and working conditions of people by actively involving them in the research process and thus broadening their horizons and empowering them to improve their situation. The radical idea of knowledge democracy is to recognize and respect the existing knowledge and epistemologies of traditional communities, ethnic tribes, socially marginalized groups and grass roots movements as valuable resources, essential for the comprehensive understanding required to find solutions to complex local as well as global problems. Nevertheless, the question arises whether science and alternative knowledges really are compatible and on an equal footing? Is science not superior to all other knowledge systems? On the other hand, is science and its exclusive claim to rationality and universalism not the back side of the colonial project of 'epistemicide' -- the subjugation and eradication of all traditional knowledges worldwide? Do not some of these knowledges offer ways of thinking that are valuable and eye-opening but inaccessible to science? Well known examples of a fruitful dialogue between different epistemologies are ethnobotany, complementary medicine and ethnomathematics. Knowledge democracy means appreciative exchange of different perspectives which through collaboration and partnership between local people and researchers can lead to sustainable solutions of complex problems, more self-consciousness and emancipation from social constraints.