盖梯尔问题之后，知识是得到辩护的真信念这个传统的三元定义受到了很大的冲击。面对盖梯尔问题，知识论领域掀起了关于知识定义的广泛讨论，内在主义与外在主义、基础主义与融贯论进行了长期的争论。到底什么样的知识定义能够经得住盖梯尔反例的挑战呢？在这样的背景下，德性知识论作为一种新兴的知识流派应运而生。最初索萨提出德性知识论是想要解决盖梯尔问题引起的知识定义危机，但实际上索萨解决知识问题的方法的本质在于它是以知识的价值问题为核心来挖掘知识的本质，构建以理智德性为基础的知识规范性。因此，本文首先从当代知识价值问题淹没难题出发切入到索萨的德性知识论体系，考察了知识价值问题的由来以及这个问题在当代盖梯尔问题影响之下的深化和发展。知识何以有价值？知识为什么比单纯的真信念更有价值？这个问题最早由柏拉图在《美诺篇》中借苏格拉底之口提出。柏拉图认为知识是得到辩护的真信念，因此，在实践的过程中，知识比单纯的真信念有更高的稳定性持久性。但是随着盖梯尔问题对传统三元定义发起挑战，知识是得到辩护的真信念的定义已经无法立足。

后盖梯尔时代，如果我们仍然坚持知识更有价值，我们就需要进一步说明为什么知识比那些因运气而得到辩护的真信念更有价值。可靠主义尝试在知识的辩护上增加额外的条件，提出知识是通过可靠过程而获得的真信念。但是这种观点遭到了扎格泽博斯基的反对，她认为可靠主义的知识论无法通过淹没难题的挑战。增加可靠过程是为了保证最后形成的信念为真，但当我们已经形成真信念，可靠过程作为形成真信念手段的价值就会被最终真信念的价值淹没。可靠过程就是一个不必要的条件。而普理查德更进一步指出淹没问题的本质是针对认知价值真理一元论。当我们把真信念看作是唯一的认知价值，任何作为达到真的手段的工具性价值就必然会被真这个最终价值所淹没。

淹没问题使我们不得不认真思考，知识本身的价值到底是什么？知识的价值难道只在于真理所赋予它的价值吗？知识是否具有最终的独立价值呢？德性知识论认为知识是认知主体运用理智德性而产生的真信念，信念之为真不是出于运气，而是出于德性。知识是适切的真信念。借助于理智德性概念，德性知识论就排除掉了盖梯尔所说的运气的因素。也是借助于这个概念，索萨把主体内在的稳定的德性同外在的真联系起来。如此便可平息当代知识论领域内在主义与外在主义的争论。对于理智德性概念，索萨认为它是主体所具有的稳定的能力。而这样一种可靠主义的德性观，遭到了以扎格泽博斯基为首的德性责任主义者的反对。经过激烈的争论之后，索萨提出责任主义是德性可靠主义的辅助理论，积极自愿的基于品质的德性只是可靠能力的理智德性的一个特例。本文对于索萨融合责任主义，但仍坚持可靠主义德性观的态度基本持肯定态度。并且认为后期索萨基于表现规范性，将主体的能力或胜任力划分为构成胜任力、内在胜任力和完全胜任力三个层次。这样的划分正反映出理智德性概念的能动性和品质的层面。

基于对索萨德性知识论的理解，本文从知识的基础性价值地位、蕴含策略到等价论证依次递进地分析了索萨对于淹没难题的回应。实际上在回答价值问题上，德性知识论具有天然的优势。淹没难题出现的根本原因就在于它有一个认知价值真理一元论的预设，因此，要反驳淹没难题，首先需要反驳的就是这个前提。在这一点上，索萨认为真理确是我们追求的认知目标，具有基础性认知价值地位，但实际上在认知评价领域，知识的基础性地位并不比真理少，知识同样是我们追求的认知目标。他指出在认知评价领域知识同样具有基础性价值地位，不过这只能够在某种程度上消解淹没难题。解决淹没难题还需要更进一步的解释。索萨认为知识是拥有超出真信念之外的额外价值的。在知识的获得中，包含着主体的认知信誉，这种来自于主体德性的额外价值在真信念的获得中是没有的。在知识的产生中蕴涵着某种来自于主体的实践价值，更蕴涵着基于主体认知表现的表现价值。尤其是表现价值能够彻底地回答淹没难题。但是索萨对于知识价值问题的探究并没有止步于此。而是进一步借助于等价论证提出了知识的规范属性，将知识的价值问题等同于知识的规范问题。也正是借由这一点，笔者看到了知识的价值与知识的规范性之间的联系以及索萨的德性知识论的真正核心在于他想要构建一种以表现规范性为基地的知识的规范性。

因此，接下来本文从认知规范性的角度对德性知识论进行了梳理。我们的信念、知识都可以被看作是一种特殊的表现，都具有一个手段-目的的结构，因此都可以根据AAA结构对其作出评价。构成知识的认知规范性就是一种表现规范性。根据表现规范性，索萨把知识区分为动物知识、反思知识和完好之知。而适切性是知识作为一种表现的最低标准。在最低标准上，知识至少是一种适切的真信念，是主体适切的表现。在这个层次上，主体获得的是一种动物层次的知识；而当知识的获得反映出主体的反思能力，主体适切地关注到适切信念，这就是一种更高层次的表现，主体具有了反思之知；当反思知识帮助引导第一层次的信念使其适切时，这时主体是完全地知道的状态，具有完好之知。在认知规范性层面上，动物知识比单纯的真信念更好，反思知识是比动物知识更高层次的状态，而完好之知则比反思之知还要好，是最高层次的认知状态。到此为止，我们能够更清楚地看到索萨的德性知识论不仅是在回答知识的本质问题，更是在追求知识的价值。以表现为基地的认知规范性理论，使我们看到，我们的认知活动不仅要追求知识的真，更要追求知识的善，追求一种在认知上具有独特价值的完好之知。

实际上知识的价值问题与知识的规范性问题是密切相关的。我们为知识寻求独特价值的过程实际上就是在为知识确立规范性的过程。里格斯提出价值转向的概念，声称当代知识论的讨论已经从以本质驱动的知识论转向以价值驱动的知识论。索萨的德性知识论能够完美地给出关于价值问题的回答，正是因为索萨的德性知识论是一种以知识价值为驱动的认识论研究方法。它的核心就在于追求知识的价值，根据知识的价值来说明知识的本质是什么。知识是一个规范性概念，知识的价值就蕴含在知识规范性的建构之中，知识区别于真信念的独特价值就在于它所具有的规范性价值，而这一点正是彻底解决淹没难题，回答当代知识价值问题的关键。知识的价值不仅仅是为真，更在于知识为我们提供了某种认知规范。我们认知活动的规范就在于追求知识，追求完好之知。

After the Gettier Problem was proposed, the traditional definition that knowledge is justified true belief took a big hit. In the face of Gettier Problem, a wide debate around the definition of knowledge has aroused in epistemology, and there has been a long debate between internalism and externalism, foundationalism and coherence. What kind of definition of knowledge can stand up to the challenge of Gettier counterexample? In this context, the virtue epistemology came into being. The virtue epistemology was first put forward by Sosa. At first, Sosa proposed the virtue epistemology to solve the crisis of knowledge definition, but in fact the essence of Sosa’s method lies in that it takes the value of knowledge as the core and constructs the knowledge normativity based on the intellectual virtue. Therefore, this paper starts from the contemporary value problem of knowledge that is the swamping problem, and investigates the origin of the value problem and its development under the influence of Gettier problem. Why is knowledge valuable? Why is knowledge more valuable than merely true belief? This question was first raised by Plato in the Meno. Plato thinks that knowledge is justified true belief. Knowledge is more stable than merely true belief in practice. But under the challenge of the Gettier problem, the definition that knowledge is justified true belief has lost its footing.

If we still insist that knowledge is more valuable, then we need to go further and explain why knowledge is more valuable than true beliefs that are justified by luck. Reliabilism attempts to add additional conditions to knowledge by proposing that knowledge is true belief acquired through a reliable process. But this view was rejected by Zagzebski, who argued that reliabilism could not overcome the challenge of The swamping problem. The purpose of adding reliable process is to ensure that the final belief is true, but when we have got true belief, the value of reliable process as a means of forming true belief will be swamped by the value of the final true belief. Then a reliable process is an unnecessary condition. Pritchard further points out that the essence of the swamping problem is directed against the truth-monism. When we regard truth as the only basic cognitive value, then any instrumental value as a means is bound to be swamped by the ultimate value of truth. 

The swamping problem makes us think about what is the value of knowledge itself. Is the value of knowledge only in the value which the truth transfers to it? Does knowledge have ultimate independent value? In virtue epistemology, knowledge is true belief out of intellectual virtue, belief that turns out right by reason of the virtue and not by luck. It is aptly true belief. Virtue epistemology excludes the element of luck, and connects the internal stable virtue of the subject with the external truth, so as to settle the debate between internalism and externalism. Intellectual virtue is the subject’s stable competence, which was opposed by responsibilist virtue epistemology led by Zagzebski. After heated debates, Sosa proposed that we can best understand the responsibilist, character-based intellectual virtues as auxiliary to the virtues that are a special case of reliable-competence intellectual virtue. This paper holds a positive attitude towards Sosa's view. Based on the performance normativity, Sosa classifies the competence of the subject into three levels: the constitutional competence, the inner competence and the complete competence. This division reflects the active and character aspects of the intellectual virtue.

Based on the virtue epistemology, this paper analyzes Sosa's response to the swamping problem from three respects: the foundational value of knowledge, the entailment strategy and the equivalent argument. In fact, virtue epistemology has a natural advantage in answering the value question. The inner reason for the swamping problem is that it has a presupposition of the epistemic value truth monism. Therefore, to refute swamping problem, the first step is to refute this premise. Sosa believes that truth is indeed the cognitive goal and has the status of fundamental cognitive value. However, in fact, in the field of evaluation, knowledge has no less fundamental status than truth, and knowledge is also the cognitive goal we should pursue. But to solve the problem we need further explanation. Sosa believes that knowledge has extra value beyond true belief. Knowledge entails the cognitive credit of the subject, and this extra value from the subject's virtue can not be found in the acquisition of true belief. Knowledge entails praxical value from the subject, and more importantly, it entails the performance value based on the cognitive performance of the subject. In particular, performance value can completely answer the swamping problem. But Sosa's exploration of the value of knowledge does not stop. He then proposed the equivalence argument to prove the normative property of knowledge. It’s just at this point, the author sees the connection between the value of knowledge and the normativity of knowledge, and the real core of Sosa's theory is to establish the normativity of knowledge base on the performance of normativity.

Next, this paper sorts out the theory of virtue epistemology from the perspective of cognitive normativity. Our belief and knowledge can both be seen as a special case of performance, as they all have a means-end structure, therefore can be evaluated in terms of the AAA structure. The cognitive normativity of knowledge is a special case of performance normativity. According to performance normativity, Sosa divides knowledge into animal knowledge, reflective knowledge and full knowledge. And aptness is the minimum standard of knowledge as a kind of performance. In the minimum standard, knowledge is at least apt belief, and the subject’s apt performance. At this level, the subject have animal knowledge. When the acquisition of knowledge reflects the reflective ability of the subject, the subject aptly notice the the apt belief, then this is a higher level performance, the subject has reflective knowledge. When reflective knowledge helps to guide the first-order belief so that it is apt, the subject knows full well. According to the cognitive normativity, animal knowledge is better than merely true belief, reflective knowledge is a higher level state than animal knowledge, and full knowledge is better than reflective knowledge, it’s the highest level of cognitive state. So far, we can see more clearly that Sosa's virtue epistemology is not only in response to the nature of the knowledge, but also in the pursuit of the value of knowledge. It’s a theory of cognitive normativity based on performance. Our cognitive activity is not only to pursuit the truth of knowledge, but also to pursuit the goods of knowledge, to pursuit full-well knowledge.

In fact, the value problem of knowledge is closely related to the normativity of knowledge. The process of seeking the unique value of knowledge is actually the process of establishing the normativity of knowledge. Riggs put forward the concept of value turn, claims that the discussion of contemporary epistemology has shifted from nature-driven epistemology to value-driven epistemology. The reason why Sosa's virtue epistemology can perfectly answer the value problem, is that Sosa's theory is a value-driven epistemological research method. Its core lies in the pursuit of the value of knowledge, according to which it explores the nature of knowledge. The value of knowledge lies in the establishment of the normativity of knowledge. Knowledge is a normative concept, and the value of knowledge lies in its normative value. This is the key to solve the swamping problem and answer the contemporary value problem of knowledge. The value of knowledge is not only its truth, but also that it provides us with certain cognitive norms. The normativity of our cognitive activities lies in the pursuit of knowledge and the pursuit of knowing full well.