语言变化的动因、特征和趋势

Motivation,Features and Trend of Language Change

语言变化的实质是与它的动因、特征和趋势密切相关的。语言变化的动因分为外因和内因。外因为对社会的依赖性,内因为交际职能和交际能力间的动态平衡,该平衡是由经济（省力）和明晰二者间相互作用引起的。外因促使内因起作用而内因又在一定程度上制约外因起作用。二者共同决定了语言变化的特征：渐变性、不平衡性和系统性。同时,语言在演变过程中呈现不断简化的趋势。

Essence of language change is closely related to motivation, features and trend of language change. Motivation of language change consists of the external motivation and the internal motivation. The former means dependence on society while the latter means the dynamic equilibrium between the communicative function and the communicative capacity caused by interaction between economy （least of effort） and clarity. The external motivation promotes the internal motivation and the internal motivation constrains the external motivation to some extent. Their combined effects determine the features of language change： scale, imbalance and systematicity. Meanwhile, language tends to be simplified in the process of evolution.