Читать книгу Educational Explanations - Christopher Winch - Страница 31

It may be the case that an explanatory theory P turns out to be true in one context but not in another. Given what we have just said about causal fields this is often likely to be the case. So we have to qualify what has been said above to take account of context. If P is false in context C1 then not-P is true in C1. But it may turn out that P is true in C2 in which case not-P is false in C2.¹¹ All explanations in educational research need to have a contextual limit placed on them. In order to explain this, it will be useful to introduce the idea of an explanatory field. An explanatory field is a causal field which admits a broader range of explanations than those allowed by efficient causality; in particular it allows for reason explanations as well. It is one of the great challenges of EER to determine what the relevant explanatory field is in determining the scope of an educational explanation. There can, unfortunately, be no simple answer to this question.

An explanatory field covers a range of situations in which explanations of a certain kind are valid. What we mean by a valid explanation will become clearer in the following two chapters. Causal fields are explanation relative. They are specified in terms of the phenomena to be explained. Thus, to use Mackie’s examples, a house and its history will be the relevant causal field when explaining the cause of the fire in the house. Exposure to a virus may have the causal field of human beings when investigating the conditions in which the viruses are present. However, when investigating the conditions under which the virus is contracted, we may restrict the field to those human beings who contract the virus. Sometimes the causal field can be very broad: explaining the influence of gravity on physical entities will take the known universe as its causal field, on the background assumption of uniform influence of gravity across it.

Explanatory fields of considerable generality cannot, however, be assumed when investigating educational practices and institutions. Not just the intensional nature of the investigation is important (the field is determined according to the scope of the investigation and hence the purposes and interests of the investigator), but there are also likely to be many different factors influencing outcomes in different contexts, including for example, cultural traditions, the labour market, attitudes towards education, income differentials, class or caste structure and political configurations.¹² It may be that there are factors which could influence outcomes of which researchers are not even aware. We have to deal with the inescapable fact that contextual factors, often hidden, will limit the scope of explanatory fields when seeking to understand the nature and operation of educational practices and institutions, the main focus of EER.¹³ This does not mean, pace Barrow, that there can be no broad explanatory fields in EER, nor that explanations valid in one context may not be valid in another, but it does mean that there has to be great caution when postulating such fields and great care taken in providing valid explanations so as to eliminate hidden factors that could upset results. An alternative approach could be iterated investigations in a variety of different contexts, leading to the inductive building up of a relatively broad explanatory field.¹⁴

What are the issues that need to be taken into account when delineating explanatory fields? The first is researcher intention, which will specify the range of phenomena of interest. Thus an investigation of the efficacy of a method of teaching reading for young children may be quite general, and apply to all practices which use an alphabetical script. In such a case the explanatory field covers the teaching reading practices (and, probably, associated factors) in societies which use alphabetic scripts. It is more likely, however, that concern will be focused on one particular writing system, say English, in which case the causal field will be those teaching reading practices that involve the English-spelling system. It is also quite possible that the explanatory field will be teaching reading practices in a particular local authority, as in the West Dunbartonshire study already mentioned (MacKay 2006). This is by no means to say that other studies in other explanatory fields may not be drawn on in constructing an explanation in this case, but other results and explanations require interpretation in the context of a new explanatory field.

At the start of any investigation researchers usually have a good idea of what factors will be relevant. In the case of intervention studies this will involve determination of those known factors whose influence is likely to be important, but which is not yet known. These factors can be incorporated into a study in different ways depending on the methodological strategy employed. For example, a quantitative study of teacher effectiveness¹⁵ will take into account factors that are known to be likely to influence effectiveness (e.g. qualifications, training, class size, and characteristics of pupils) to an unknown degree, and these can be incorporated into the design. However, factors that are not known to be likely to influence teacher effectiveness are, by their nature, difficult to include in a study. The disturbing fact is, however, that they may be present and active. To some extent such worries can be alleviated by a successful empirical study.

One could argue that this should not be possible. Since the work of Fisher, R.A. (1935) experimentation has involved randomisation of a population sample prior to assignment to treatment and control groups. This supersedes the earlier procedure of controlling for all known variables that could be effective (Brown and Melamed 1990). The key advantage of randomisation is that it should capture all possibly relevant factors in the population and the random assignment to treatment and control groups should ensure that they are present to an equal degree in both groups.

The problem, as we shall see in Chapter 8, concerns what the relevant population actually is. The problem is acute in EER because we cannot make assumptions about population uniformity even across urban districts (Webber and Butler 2007), let alone regions, nations and cultures. In other words, context is extremely important in determining what the relevant population is going to be. An RCT which tests a particular teaching intervention can be shown to be likely to be effective in a particular context. We can be reasonably confident that ‘it works here’ (Cartwright and Hardie 2012).

We cannot infer from the fact that it works here to the likelihood of its working elsewhere because we may not know the background conditions which enabled it to work here and which might militate it working somewhere else. The relevant explanatory field for the RCT is the particular context (local authority, jurisdiction or whatever) in which the intervention was successfully trialled. Working stepwise we can trial it in other contexts, not knowing whether these should constitute different explanatory fields, but we cannot always expect the same result because other factors may be in operation in other contexts. They may operate directly on teacher effectiveness or they may have an effect on those factors that are known to have such an effect. In either case, it may be that we are unable to extrapolate ‘what works’ from one context to another, and we will have to proceed by trial and error in determining the sense of explanatory fields.

When we find that an intervention does not work in another context, but with the same ‘known unknowns’ then there is a prima facie case for thinking that a fresh explanatory field is involved and a corresponding need to identify the background factors that are at work. These may be causal or they may be normative or motivational factors. Either way, they are pertinent to the explanation of the intervention depending on the kind of explanation which it is appropriate to look for.¹⁶ If, for example, we were concerned with the successful or otherwise taken up by low-income parents of voucher schemes for private schooling, previous research (including qualitative research into attitudes) and more general knowledge of cultural background would allow researchers to identify factors that need to be taken account of in sampling a population of parents. These might not be sufficient, however, to identify influential factors that turn up in some context but not in others or which influence ‘known unknowns’ in some cases but not in others.