Débats anthropologiques sur la rationalité et les modes de pensée

This essay is based on Steven Lukes work Some Problems about Rationality and Robin Horton's work African Traditional Thought and Western Science.
The anthropological debate on the rationality of the primitive mode of thought is linked with a problem of method for anthropologists. How an anthropologist can face a belief that seems to be irrational?
Is it the purpose of an anthropological study to give a judgment on the rationality of a belief or a mode of thought? If yes which criteria can be used to make the study in a scientific way? We have to question the anthropological approach of one of the main anthropological object: do primitive's people have alternative standards of rationality?