EL CARÁCTER FUNCIONAL DEL VALOR TRABAJO KARL MARX

The DN theory, first proposed by Hempel and Oppenheim in 1948, kickstarted the modern debate about the nature of explanations in science. Subsequent theories have, to a large degree, been developed as a response to the recalcitrant counterexamples to the DN theory. An introduction to the theory is aided by noting the ideological background of its creators. While it is a natural thought that to explain some

phenomenon is to identify its causes, Hempel and Oppenheim’s positivistic leanings made them highly sceptical that we could come to know about dubious ontological posits such as relations of causation. Thus they excised any mention of causation from their theory, instead presenting explanations as arguments from explanans to

law of nature (hence ‘nomological’), usually coupled with a description of some state of affairs. The state of affairs together with the laws entails the explanandum, and each premise must be required for this derivation.

In this way the explanatory burden is shifted away from an ontology of causal relations and onto an ontology of laws of nature, a notion which proponents of the view found more continuous with scientific discourse.42 _{As such, this theory holds that}

explanations track relations of nomic determination. It is the notions of logical structure and laws of nature doing the work in cleaving the potentially explanatory relations from the rest. We will consider four incarnations of the DN theory here: the unfiltered view, and three methods of filtering—the psychologistic DN theory, the Kairetic theory, and the unification theory.

It will be no surprise that the DN views have been heavily criticised for a lack of an adequate account of laws of nature (see, e.g., Cartwright, 1983. Even Hempel himself voiced the complaint that characterising the laws has proved “highly recalcitrant” (1965:338)). Hempel and Oppenheim characterised the laws of nature as ‘non-accidental generalisations’. This is a notion we have an intuitive grasp on, but is notoriously difficult to nail down. Hempel (1965) distinguishes the generalisation that ‘all members of the Greensbury School Board for 1964 are bald’ from the generalisation that ‘all gases expand when heated under constant pressure’. The latter strikes us as lawful while the former does not. As our intuitions are clear in cases such as this, Hempel ultimately takes a ‘we know ‘em when we see ‘em’ approach. While in many cases this may be true, the lack of a precise account of the laws of nature remains a problem for DN theories, one to which we will return in Chapter 6.

The DN theories do well with covering cases. Many actual scientific explanations explicitly feature the DN form, and for those that do not (for example, those which lack laws), it is open to the defender of the DN theory to claim that underlying the proposed explanation is a DN derivation. As long as there is a DN explanation to be had with the same events in the explanans and explanandum, the theory has the case covered. It also does well with irreflexivity, as presumably there is no law of nature connecting an event with itself.

42 _{One might demur on the grounds that talk of causal processes is as much a staple of scientific discourse}

as talk of laws of nature. Nothing in what follows hangs on whether Hempel and Oppenheim were right to think that laws are less metaphysically suspect.

However, DN theories struggle with asymmetry. The problem derives from the apparently symmetrical characteristics of the laws of physics (see e.g., van Fraassen, 1989). These lawful symmetries allow many DN derivations where the explanans and explanandum are inter-derivable from the same law. For example, the current

arrangement of our solar system is equally derivable from how it was arranged yesterday (in combination with the laws) and how it will be arranged tomorrow (in combination with the laws). Yet many feel the intuition that the latter ought not count as an explanation.

Furthermore, there is a problem with relevance. The minimal characterisation of the laws of nature allows seemingly irrelevant information to be included in the

explanans, yet the argument still be deemed an explanation. To use another classic example, barometer readings are reliably (and non-accidentally) correlated with storms. Thus one can construct a DN argument whereby the barometer’s reading explains the occurrence of the storm (via a ‘barometer-storm law’), despite a strong intuition that both the reading and the storm were explained by the change in air pressure.43

Finally, the DN theory allows for explanations that are beyond human

comprehension and thereby fail to increase our understanding. For, there is surely an immensely complex DN derivation from the initial state of affairs of the universe, together with the laws of nature, to any current state of affairs. For example, the fact that the curtains in my study are black can be derived in this way.

The different sub-categories of DN theory deal with these concerns in different ways. The unfiltered DN theorist, for example, will bite all the above bullets. She will maintain the objectivity of what explains what, at the cost of abandoning asymmetry, relevance and understanding. This move is part of a more general strategy of shrugging off objections that the candidate relations outstrip the intuitive explanations by appealing to ontic intuitions about explanation. If explanation is an objective feature of the world, it is plausibly one to which our intuitions provide a poor guide.

At the other end of the spectrum, the psychologistic DN theorist will say that only those DN derivations that fulfil the epistemic desiderata should count as explanations.                                                                                                                

43 _{This kind of irrelevance is not of the ‘tacking on idle wheels’ kind, but rather a case where the entire}

explanation appears to be idle. Irrelevancies of the former kind are avoided by appealing to the principle of

minimality, whereby every premise in a DN derivation must be required for the validity of the argument.

Thus, she will jettison the objectivity of what explains what in order to have a theory that excludes symmetrical and irrelevant derivations, as well as those that fail to increase our understanding. This kind of position is motivated by arguments such as van Fraassen’s (1980) that what explains what is determined contextually, by the interests and

knowledge of the question-asker. Thus the view is explicitly anthropocentric, and the truth of explanatory claims is relative. However, such a position needn’t appeal to the contexts of individuals, like van Fraassen’s theory. Presumably there is some unity in the kinds of things that humans find explanatory. So we can think of the psychologistic filtration here as representing human interests and understanding. There is evidence that Hempel himself was sympathetic to such a view, as he responded to the symmetry counterexamples (e.g., the famous pole and shadow case) by relegating the choice between the two directions of derivation to ‘pragmatics’ (1965).

Each of the remaining pair of DN views tries to ride the line between the above approaches, maintaining the objectivity of what explains what without allowing too many counterintuitive explanations. Strevens’ (2008) Kairetic account, for example, appeals to further in-the-world considerations to filter the candidate relations provided by the DN theory in a non-psychologistic way. The Kairetic view has it that in addition to satisfying the DN argument form, a putative explanation must also represent an underlying asymmetric relation of determination in the world (including, amongst others, causal relations). The relata of this relation must be represented by the non-lawful premises and conclusion of the argument. The DN derivations which fail to track these relations are not explanations.

As such, the Kairetic account (in the scientific context) is a hybrid of the DN theory and the causal process theory (see §2.5.2), insofar as both ingredients are required. The result of this hybridisation is a powerful theory, but one with twice the baggage. Not only does the Kairetic theory need to give an account of the laws of nature, it needs to give an account of the asymmetric determination relations which must exist in re alongside every explanatory DN derivation. In this way, the ‘dubious ontology’ which Hempel and Oppenheim were trying to do away with has been readmitted, and therefore the Kairetic theorist finds herself needing to give an account of both laws of nature and causal relations.44

44 _{Strevens (2008) explicitly denies the latter point, for he takes his theory to be agnostic between all}

However, if one is happy with the commitments of the view, it achieves

asymmetry in virtue of the asymmetric nature of causal relations. However, the solution is not so simple with regards to relevance, as there are counterexamples to both the DN and causal process theories which will still be problems for the Kairetic theory (e.g. the man who takes birth control pills discussed in §2.5.2). Finally, the Kairetic theory still allows those DN derivations which fail to increase understanding. For example, those derivations from the initial state of the universe to some current state of affairs will still have an underlying causal relation. Nonetheless, the Kairetic theory remains a powerful and attractive theory.

Finally, Kitcher (1981, 1989) advocates an alternative way of filtering the DN derivations without appealing to psychologistic considerations. According to the unification view, the only DN derivations that count as explanations are those which belong to the set of arguments that best unifies all the explananda which need explaining. As such, whether a certain derivation is explanatory cannot be assessed in isolation. Instead, entire corpora of potential explanations are compared against each other to see which overall system is the best. Kitcher uses a lot of complex machinery to make precise this notion of the most unified system. We will explore the machinery in more detail in Chapter 7, but (in brief) the best system is the one which uses the fewest argument patterns to generate the biggest conclusion set. These patterns must also be

stringent, such that derivations which instantiate the same argument pattern are genuinely

similar.

The resulting theory implies that even if there is a DN derivation in the offing for some phenomenon, if this derivation instantiates a new argument pattern, and the phenomenon is already derivable by an instance of a pre-existing argument pattern, then this putative new explanation doesn’t count as an explanation. So, for example, the unificationist can avoid temporally symmetric explanations by noting that if we already use past-to-future explanations, adding future-to-past explanations decreases the unification of our system. However, this idea of ‘already using’ explanations from past- to-future is misguided (as we discussed in §1.2). A systematisation which makes use of either the past-to-future or future-to-past pattern will be equally unified, for the machinery provided by the theory can only rule out that they exist side-by-side. Thus, arguably, asymmetry is satisfied, but it remains underdetermined whether past-to-future

or future-to-past explanations are correct. Thus, Kitcher may have to follow Hempel’s lead in relegating the decision to pragmatics.45

The constraints of unification also prevent irrelevant premises sneaking into the DN arguments, satisfying relevance. If we can already account for some phenomenon using a derivation pattern, a putative explanation of that phenomenon using some other pattern with idle premises will be ruled out. Again, this will be presented in much more detail in Chapter 7. However, nothing in the view rules out incredibly complex DN derivations which fail to increase our understanding.

So, there are four DN-based views of scientific explanation, which perform differently according to the desiderata. Which view does best overall will depend, of course, on how one weights the desiderata. Notably, for those who emphasise the epistemic nature of explanation, the psychologistic DN view can fulfil all of the other desiderata by giving up on objectivity. Of the objective theories, the unification view does best in securing the epistemic desiderata, but (arguably) still falls short.