In this paper about Chile, Weber's taxonomy of rational behavior is used together with a genetic-structural approach to explain chilean political life, which can be understood by the following variables: a mean demography, an authoritarian and religious culture, a capitalistic, dependent and under-developed economy, an hybrid social stratification, a centralised state characterized by an higly developed burocracy. In such a context the «Popular Unity» results from a specific acculturationof antagonistic ideologies related to different social strata, to competitive political groups as well as to rival pressure groups. In the short term; the confiicting interests might coexist thanks to a growing social support motivated by a superficial economie nationalism, emotional anti-capitalistic feelings and the rise in the income of the popular and middle classes strata.On the other hand, the left government, divided by social, political and ideological oppositions was unable to run the civil service, to structure a congruent economic policy and to face international or national subversion.