David Lewis's Counterfactuals

The aim of this paper is to introduce David Lewis's (D.Lewis) the theory of counterfactual in the solution of causation, and make my evaluation. The paper analyses the theory in the treatment of such problems as the advantages of counterfactual that the true value of the conditional distribution,preemption and really systematically studied the counterfactual etcAlso pointed out the shortage of theory, such as temporal asymmetry, preemption and transitivity etc.The paper is divided into five parts.The first part, briefly introduce the theory of causation before the David Lewis's couterfactaul. I review the main problems in the theory of causation from Hume to D.Lewis in the aspects of language and logic.David Lewis's counterfactual is the first real system effectively handle the truth conditional problem of counterfactuals.The second part, I sorte and introduce the key points in the theory of counterfactuals.This theory solves the main problem that the true value of the conterfactuals.In dealing with the true value problems of the conterfactuals, Lewis assigned to the possible world in a new way that constructs a strict and changeable system of spheres. At the same time, he discaussed the true value problem of counterfactuals in the centered system of spheres,and completely assigned true values to counerfactuals. In this section,I also introduce some equivalent system to centered system of spheres,such as Comparative Similarity system of spheres and Comparative Possibility system of spheres etc.We can see his theoretical characteristics and advantages. And for the third part of causation analysis provides the necessary preparations.The third part introduce what is the main relation between the Lewis's theory of counterfactual and causation,and how he solve the main problems of causation in the causation theory from Hume. He definites a very improtant conception:the causal dependence.It means: 'where c and e are two distinct actual events ,e causally depends on c,if and only if ,if c were not to occur e would not occur.'~2This definition makes counterfactuals and causation together,and then makes that use counterfactual theory to analysis causation becomes prossible.It invents a new way to solve the problem of causation.In this section,I analysis some original problems,such as transitivity,preemtion,etc.Overall Lewis theory is more energy ,and has stronger explainary than the original theory.In fourth part,I mainly discusse and analysis some very classical examples which can't be solved with the theory of counterfactual theory.There are three main problems that can't be solve with Lewis's theory:the problem of context-sensitivity,the temporal asymmetry,and transitivity and preemtion.I give my own analysises in those problems and give my own opinion on the original discussion.The fifth part is the conclusion.I summarize the theory for the Lewis causality provided for solving the problem of new ideas and new ways. Through his efforts and constant improvement of others, counterfactuals theory has become the important theory with causality.