The progress of science will allow science to answer tradional metaphysical questions such as "What is knowledge?", "What is reality?", "Why reality appears to us to contain objects, properties, categories, space, time, a subjective and an objective part, etc.?". Science forces us to interpret reality as adaptiation to the environment and to recognize that the knowledge of reality possessed by human beings (the animals that do science) is part of their specific adaptive pattern, and therefore is relative to this type of animal and not absolute. Science will be able to answer traditional metaphysical questions by construcing robots with different bodies, different sensor and motor organs, different brains, and different evolutionary histories. If we can construct really "human" robots, which are very different from current "humanoid" robots, we will be able to determine what is reality for them and to contrast their reality with the reality of other, animal-like, robots.