人类关于因果关系的理解有一个缺陷,这限制了人们决策思维的合理与有效.在中国,这一思维缺陷部分地源于形式逻辑,特别是形式逻辑中关于假言推理的理论.传统形式逻辑中关于假言推理的理论把"条件"与"结论"的关系分成四种,即充分、必要、充分必要条件及(隐含的)非条件.传统的假言推理分类形成一个事实上的因果分类体系,把原因分为充分、必要、充分必要原因及(隐含的)非原因这四类.这一传统的因果关系分类遗漏了一个重要的原因类别--部分原因.这一遗漏可能部分地导致了思维、讨论、争辩、决策中的许多歧义、混乱与缺失.有鉴于此,笔者提出了一个新的因果分类体系,把原因分为充分、必要、充分必要、部分原因及非原因这五类.下一步的研究应当论证这一新体系的完整性,即它的包容性与互斥性,并在此基础上计算各类因果关系出现的概率.笔者认为,探讨这一问题直接目标在于给因果关系分类,而给因果关系分类是为了建立更为科学的决策思维方式.由于形式逻辑传统上不把因果关系或决策思维方法作为主要研究对象,所以,就其目标而言,所探讨的问题不属于形式逻辑的范畴.从某种意义上说，笔者是旨在思维方法、形式逻辑、科学方法论、决策科学以及各个涉及因果判断的实证学科等许多学科之间的一个跨领域努力。

The understanding of human beinga to causal relations has defects,which limits the rationality and avail- ability of policy thinking.In China,the thinking defection is partly due to formal logic,especially,the theory about modus ponens,The theory about modus ponens in the traditional formal logic separates the relation of condition and result into four types:full conditions,cssential conditions,full and essential conditions,and hidden conditions.Thus a true system of causal relations takes shapo,which separates causes into four types, ruch as full couses,essential causes,full and essential causcs,and hidden causes.The traditional typology of causal relations loses partial causcs,which may partly lead to a lot of different meanings,confusion and lacks of thought,discussion and policy.The author brings out a new system of typology of causal relations,which separates causes into five types as follows:full causes,essential causes,full and cssential causcs,partial causes,and hidden causes.The next investigation is to expound and prove its completeness,which consists of inclusion and altemative,and count the pobability of all the kinds of causal relations.The author bolds that the gonl is to build more scientific palicy-thinking mode,As the formal logic traditionally doesn't regard causal relations or policy-thinking mode as major object of study,the paper docsn't belong, to the category of fonnal logie.The author tries to pass through thinking methods,formal logie,scientifie methodology,policy science and all the positive subjects related to causal judgment.