Choices of Evidence. Tacit philosophical assumptions in the debates within the Campbell Collaboration

基于证据的政策现在在整个英国和美国都得到了强制执行，在欧洲，在国际、国家和地方层面上也越来越多。以Cochrane在医学领域的合作为蓝本，Campbell Collaboration是一个独立的、国际的非营利性组织，其成立的目的是向决策者提供基于证据的信息，使他们能够就社会、行为和教育领域的干预措施的影响做出明智的决定。然而，无论是在坎贝尔的合作中，还是与批评者之间，都存在着重大的争论，即在以证据为基础的政策和实践中，什么是可接受的证据，以及如何判断其作为特定假设支持的力量。这个项目专注于儿童社会福利和教育的案例研究，旨在通过分析为他们提供信息的哲学假设来澄清和帮助解决这些争议。鉴于知识库的水平和主题的复杂性，大多数争议似乎源于对应该提供什么证据以及它可以提供什么的不同要求。我们将研究一些已经确立但又有争议的区别，我们猜测这些区别会增加辩论的混乱。反对者似乎常常无法理解对方的立场，因为他们含蓄地对社会世界的性质或科学方法采用了不同的哲学假设。首先，定量数据和定性数据：两者之间的区别被广泛接受，前者通常被认为比后者更有效和可靠。但在社会福利和教育领域，从业者的推理依据是关于人们行为的不全面和模棱两可的数据。定量数据和定性数据究竟在哪些方面有所不同？前者据称在哪些方面更可靠。一个相互关联的问题是客观和主观之间的区别，这在实践中变成了一般知识和地方知识之间的区别，即方法/专门知识和更多以判断为基础的方法之间的区别。能否在不牺牲当地知识的情况下获得研究方法的一般知识和专业知识的优势？第三，社会福利领域提出了一些问题，即在社会干预中，谁决定什么是解决方案，以及应如何处理/裁决相互竞争的索赔。在一个涉及社会中最弱群体的学科领域，这个问题特别重要。第四个问题是，清晰的方法层次是否无意中导致了问题的层次，不可避免地优先考虑了那些可以用排名较高的方法研究的问题。第五个问题涉及“确定”证据方法(它们的结论是从肯定的结果推导出来的)和“担保”方法(由被认为令人满意的、可能相关的证据支持的结论)之间的区别。确定证据需要如此多的假设和条件，我们担心其应用变得非常有限。应该如何处理适用范围和结论确定性之间的权衡？最后一个问题是对封闭和开放研究方法的区别提出质疑。前者，如随机对照试验，有内置的设备，用于检查应用该方法所需的假设。后者，如贝叶斯网络，需要求助于其他设备。需要通过封闭的方法提供最好的证据，还是可以接受范围更广的证据？这些分析的结果将为阐明符合实际研究要求和需要的科学哲学提供基础。我们将致力于提出一种理论上合理和现实上可执行的证据理论，从而有助于坎贝尔项目的成功发展。

Evidence-based policy is now mandated throughout the UK and the USA, and increasingly in Europe, at international, national and local levels. Modelled on the Cochrane Collaboration in medicine, the Campbell Collaboration is an independent, international, non-profit organization which has been set up to provide 'decision-makers with evidence-based information to empower them to make well-informed decisions about the effects of interventions in the social, behavioural and educational arenas' (www.campbellcollaboration.org). There are, however, major debates, both within the Campbell Collaboration and with its critics, about what counts as acceptable evidence in evidence-based policy and practice and how its strength as support for a particular hypothesis can be judged.This project, focusing on the cases studies of child social welfare and education, aims to clarify and help resolve these controversies by analysing the philosophical assumptions that tacitly inform them. Most of the controversies appear to originate from different demands put on what evidence should deliver and what it can deliver, given the level of the knowledge base and the complexity of the subject matter. We shall examine a number of well-established and yet disputable distinctions that we conjecture add confusion to the debate. It often seems that opponents are failing to understand each other's positions because they are implicitly adopting different philosophical assumptions about the nature of the social world or of scientific method.We shall address six key issues. First, quantitative and qualitative data: a distinction between the two is widely accepted with the former being generally considered more valid and reliable than the latter. But in social welfare and education, practitioners reason on the basis of partial and ambiguous data about people's behaviour. In what ways precisely do quantitative and qualitative data differ and in what ways is the former purportedly more reliable. A linked issue is the distinction between objective and subjective that, in practice, becomes a distinction between general and local knowledge, namely between methodology/expertise and more judgment-based approaches . Can the advantages of the general knowledge and expertise in research methods be gained without sacrificing local knowledge?Third, the area of social welfare raises questions about who decides what counts as a solution in social interventions and how competing claims should be handled/adjudicated. In a subject area that deals with the least powerful groups in society, this issue is of special importance.A fourth issue is whether a clear hierarchy of methods inadvertently leads to a hierarchy of questions, inevitably prioritising those questions that can be studied by the higher ranked methods. The fifth question addresses the difference between 'clinching' methods of evidence (their conclusions are deduced from a positive result) and ''vouching' ones (conclusions upheld by evidence deemed to be satisfactory, possibly relevant etc. Clinching evidence requires so many assumptions and conditions that its application becomes, we fear, very limited. How should the trade-off between scope of application and certainty of conclusion be managed?The final issue questions the difference between closed and open research methods. The former, such as RCTs, have built-in devices for checking the assumptions that are needed to apply the method. The latter, such as Bayes-net,require appeal to other devices. Need best evidence be supplied by closed methods or can a wider range be acceptable?The outcome of these analyses will provide the basis for articulating a philosophy of science that meets the requirements and needs of practical research. We will aim at suggesting a theory of evidence that is both theoretically sound and realistically enforceable and thus contributes to the successful development of the Campbell project.