The research of rational crisis and reconstruction still remains very hot in the academia.The crisis of rationality lies in many factors，of which its inherent defects are an important aspect.The dissertation does the research from three perspectives and makes a conclusion that the future development of rationality depends on its returning to context once more：firstly，to consider according to the development history and reflection of rationality and its logical expectation of its future trend；secondly，to do the research according to the development trend of modern sciences and postmodern study of sciences；thirdly，through empirical cases，namely，by analyzing the relationships between the above-mentioned three kinds of rationality and their relationship with society，to verify the outcome of the research.

The research is carried out according to a historical development of rationality.

The special physical structure of human brains constitutes an important substance of human rational thinking.Besides，it not only makes human rational thinking generally similar in form and content，but also special and contextualized.Ancient people also favor logical characteristics in terms of their rational thinking，but they do not differentiate“subject and object”in their thinking，making their rationality show the property of context.Since ancient Greece，logical rationality has become the important characteristic of western rationalism，which can be explained by the unique western“intension to move forward”and their culture to fight a-gainst the nature.After ancient Greece，mathematical and logical rationality got a salient development，getting rationality decontextualized gradually.

After medieval times，scholasticism began to apply rationality to explaining religions，which is still a logical approach.The development of modern science made scientific rationality salient and made it experience the change from“essentialism”to“existentialism”in its understanding；in viewpoint of the world it has established a common mechanical view of the nature；in methodology it has formed a logical mathematical method，making modern scientific rationality become“a closed and absolute rationality of scientism”.So rationality began to show its one-sided，rigid and abstract shortcomings，which made a potential for its future crisis.Meanwhile，it made it possible for it to convert to the opposite.Two industrial revolutions and market economy have provided a consistent and stable cases in a long-term and broad time and space，and have provided a practical basis for the abstraction of technological rationality.The defects of modern scientific rationality and the overextension of technological rationality have made value rationality salient and promoted.

The future development of sciences will take place in more macro and micro fields，and take as research objects the bifurcation，chaos，random and other uncertainties of things.Postmodern sciences differs from modern sciences not only in terms of their methods to deal with objects，but they can absorb or abandon the paradigms of modern sciences with new paradigms of tolerance，understanding，cooperation，creation，selfdiscipline and heteronomy.Before modern and postmodern sciences，the priori，abstract，and metaphysical characteristics of modern rationality have been exposed.In a certain sense，they provides a momentum for rationality to turn to context.As for the reconstruction of rationality，the West has put forward an idea to change“from rationality to reasonability”，“from authoritative rationality to critical rationality”，and“from priori rationality to practical rationality”，all of which contain the contextualization of theoretical reconstruction.

Horizontally，the dissertation makes a Chinese-western comparison of the basic connotation of rationality.Especially，it makes a definition of the various rationalities through classification and the choice of appellations.Meanwhile，it puts forward two points：the overextension of rationality in form makes it contextualized in formal meaning；the scientific rationality，technological rationality and value rationality constitute the main form of human rationality.The dissertation puts forward the concept of“the view of broad-sense logic”to answer the reasonability for rationality to exist in the future context，and proposes that it be necessary to reconstruct a logical view which contains intuitive，deontic and multi-valued logics in a certain context.

Rationality has its property of ecological existence，and rational ecology has its particular structure and social function.In the future，the rational ecosystem will become more complex，and the reasonable criteria of the three kinds of rationality will tend to be more contextualized and embedded.The harmony of rational ecology has a special meaning to the sound operation of society.At present，China's rational ecology has shown its unharmonious aspect.The technological rationality has been overextended，and scientific rationality and value rationality have been lessened.The overflow of multivariant ideas against the mainstream social concepts has exerted a negative influence upon the sound operation of Chinese society.To construct a harmonious rational ecology should focus on：taking the scientific rationality as the basis，strengthening the guidance of value rationality，and restraining the overextension of technological rationality；setting up a reasonable coexisting system of concepts for the multivariant and mainstream ideas.

Wenchuan earthquake and the disputes between Chinese and western medicines can provide materials for people to understand the research objects and the characteristics of postmodern scientific research，and meanwhile they can provide realistic materials for people to understand the con-textualization shown by the three kinds of rationality in practice and their inner relationship with society，i.e.ecological property.The research outcome shows that rationality must be combined with a specific practice and specific context，and only under this condition can rationality have its significance of existence.