Causation and Explanation

Stathis Psillos

• Publisher: Routledge
• Year: 2014
• Print ISBN: 9781902683416
• eBook ISBN: 9781317489764
• Topic: Philosophy
• Subtopic: Philosophy History & Theory

What is the nature of causation? How is causation linked with explanation? And can there be an adequate theory of explanation? These questions and many others are addressed in this unified and rigorous examination of the philosophical problems surrounding causation, laws and explanation. Part 1 of this book explores Hume's views on causation, theories of singular causation, and counterfactual and mechanistic approaches. Part 2 considers the regularity view of laws and laws as relations among universals, as well as recent alternative approaches to laws. Part 3 examines the issues arising from deductive-nomological explanation, statistical explanation, the explanation of laws and the metaphysics of explanation. Accessible to readers of all levels, this book provides an excellent introduction to one of the most enduring problems of philosophy.

I Causation

1 Hume on causation

1.1 The regularity view of causation

A good starting point for our philosophical endeavours is David Hume’s account of causation. His work on this subject has been, by far, the most important and influential ever. Hume’s account has been taken to be a reductive one. It’s been typical to call this account the Regularity View of Causation (RVC).

RVC

c causes e iff

1. c is spatiotemporally contiguous to e;
2. e succeeds c in time; and
3. all events of type C (i.e., events that are like c) are regularly followed by (or are constantly conjoined with) events of type E (i.e. events like e).

So, on RVC, causation reduces to spatiotemporal contiguity, succession and constant conjunction (regularity). It reduces, that is, to non-causal facts. A corollary of RVC is that there is no necessity in causation: there is no necessary connection between the cause c and the effect e that goes beyond – or underpins – their regular association. RVC has been espoused by many eminent philosophers and has been taken to be the official Humean view. Here are a few representative statements of it.

The Law of Causation . .. is but the familiar truth that invariability of succession is found by observation to obtain between every fact in nature and some other fact which has preceded it . . .

(Mill 1911: 213)

We must ask ourselves: when we assume causation, do we assume a specific relation, cause-and-effect, or do we merely assume invariable sequence? That is to say, when I assert “every event of class A causes an event of class B”, do I mean merely “every event of class A is followed by an event of class B”, or do I mean something more? Before Hume the latter view was always taken; since Hume, most empiricists have taken the former.

(Russell 1948: 472)

In nature one thing just happens after another. Cause and effect have their place only in our imaginative arrangements and extensions of these primary facts.

(Ayer 1963: 183)

The trouble with causation is, as Hume pointed out, that there is no evident way of distinguishing it from mere invariable succession.

(Quine 1974: 5)

[a] statement about a causal relation . .. describes an observed regularity of nature, nothing more.

(Carnap 1974: 201)

[According to Hume] to say of a particular event a that it caused another event b is to place these two events under two types, A and B, which we expect to be constantly conjoined in the future as they were in the past.

(Kripke 1982: 67)

RVC has been traced to what Hume thought and said. Take, for instance, a famous passage from his Abstract to A Treatise of Human Nature, in which Hume discusses one of his favourite examples of causation, the collision of two billiard balls:

Here is a billiard-ball lying on the table, and another ball moving towards it with rapidity. They strike; and the ball, which was formerly at rest, now acquires a motion. This is as perfect an instance of the relation of cause and effect as any which we know, either by sensation or by reflection. Let us therefore examine it. ’Tis evident, that the two balls touched one another before the motion was communicated, and that there was no interval betwixt the shock and the motion. Contiguity in time and place is therefore a requisite circumstance to the operation of all causes. ’Tis evident likewise, that the motion, which was the cause, is prior to the motion, which was the effect. Priority in time, is therefore another requisite circumstance in every cause. But this is not all. Let us try any other balls of the same kind in a like situation, and we shall always find, that the impulse of the one produces motion in the other. Here therefore is a third circumstance, viz., that is a constant conjunction betwixt the cause and effect. Every object like the cause, produces always some object like the effect. Beyond these three circumstances of contiguity, priority, and constant conjunction, I can discover nothing in this cause. The first ball is in motion; touches the second; immediately the second is in motion: and when I try the experiment with the same or like balls, in the same or like circumstances, I find that upon the motion and touch of the one ball, motion always follows in the other. In whatever shape I turn this matter, and however I examine it, I can find nothing farther.

(A: 649–50)

Hume says, very explicitly, what he does find in a case where two events are related as cause and effect: contiguity, priority and constant conjunction. He doesn’t say, in this passage or elsewhere in the Abstract, what else one might have expected him to find, which Hume doesn’t. He is more explicit on this in the body of his A Treatise of Human Nature (Book I, part iii), and his An Enquiry Concerning Human Understanding.¹ Hume’s predecessors thought there were also necessary connections to be found in nature.² They thought that, when c causes e, there is something in virtue of which c produces, or brings about, or necessitates e: the cause has the power to produce the effect and the effect follows with necessity the cause. On the received reading of Hume’s Treatise, this element of necessity is exactly what Hume does not find in causation, as it is in the objects: there is no place for necessity in nature. Once more, this reading of Hume is not unrelated to his own pronouncements. Compare his famous dictum: “Necessity is something that exists in the mind, not in objects” (T: 165). Accordingly, Hume has been typically read as “the great denier of necessary connections” (Lewis 1986f: ix).

In the last 20 or so years, however, there has been an altogether different reading of Hume’s work on causation, whose origins can be found in Norman Kemp Smith’s (1941) authoritative commentary on Hume’s Treatise and in John P. Wright’s (1973) work. Wright proclaimed that far from being a reductivist about causation and an eliminativist about real necessity in nature, Hume was a “sceptical realist”. He was, we are told, a “causal realist” because he accepted the view that “there are real causes in nature” (1973: 127), that is, that there are objective necessary connections between events in nature. But, the claim goes on, Hume was a sceptic about our understanding and knowledge of them (cf. 1973: 144). This revisionary interpretative strand has been reinforced by Edward Craig (1987) and has found its magnum opus in Strawson (1989). These new readings of Hume have led to what Kenneth Winkler (1991) has aptly called “the New Hume”. Craig goes as far as to state confidently:

Off the agenda now is the idea that [Hume] taught a strict regularity theory: that there is nothing in reality but regular sequence, and that that is accordingly all that causality amounts to, either in our concept of it or in things and events themselves. True, the tendency to speak of regularity theories as “Humean” persists, but unless it is meant . .. as nothing more than a label without historical connotations, this usage just betokens a limited acquaintance with the work of Hume.

(2000: 113)

These pronouncements might be premature. Even if it can be argued that, for Hume, what we mean when we talk of causation is not just regular sequence, it is not so easy to argue that for him causation, as it is in the world, is something more than regular sequence. Be that as it may, what I plan to do in this chapter is go through Hume’s reasoning in some detail, in the hope that, in the end, we shall have a better understanding of his views on causation and their philosophical implications. In the final section, I shall engage in a discussion of the so-called “New Hume”.

Before we proceed, a note on terminology is in order. Different philosophers use the term causal realism in different ways. Strawson (1989: 84), for instance, calls causal realism the view that “there is something about the fundamental nature of the world in virtue of which the world is regular in its behaviour”. Michael Tooley (1987: 246), on the other hand, calls causal realism the anti-reductive view that “the truth-values of causal statements are not, in general, logically determined by non-causal facts”. On both characterizations, RVC would not be a causal realist position. However, it would be wrong to conclude from this that RVC is an anti-realist position. Contra Strawson’s causal realism, advocates of RVC accept that it is regularities all the way down, and yet also accept that these regularities are real, objective and mind-independent. Similarly, advocates of RVC accept, contra Tooley’s causal realism, that causation reduces to regularity, and yet they accept that these regularities are real, objective and mind-independent. So an advocate of RVC is (or can be) a realist about regularities. In so far as causation reduces to regularities, an advocate of RVC can then be a realist about causation. With these clarifications in mind, let’s reserve the term “causal realism” for those views that assert that there are objective necessary connections between events in nature as well as for those views that deny that causation is reducible to non-causal facts. And let us say that, without being causal realist, RVC is a causal objectivist position in the sense that the regularities that causation reduces to are fully objective and mind-independent.

1.2 The two projects

Hume (T: 74) states his aim very explicitly: “This relation [of causation], therefore, we shall endeavour to explain fully before we leave the subject of the understanding.” Why was he interested in the study of causation? His answer, as it is expressed succinctly in the Abstract, is this:

’Tis evident that all reasonings concerning matters of fact are founded on the relation of cause and effect, and that we can never infer the existence of one object from another, unless they be connected together, either mediately or immediately. In order therefore to understand these reasonings, we must be perfectly acquainted with the idea of a cause . . .

(A: 649)

So the relation of causation underpins all our reasoning about matters of fact. Of the three “philosophical relations” that relate matters of fact (i.e. objects in the world, or impressions), namely “identity”, “situations in time and space” and “causation”, only causation is special in the sense that it can take us “beyond what is immediately present to the senses” and can “produce a connexion” between objects that are not immediately perceived (cf. T: 73). But causation is not just a philosophical relation, that is, a relation that obtains between objects in the world, or impressions. It is also a “natural relation” (T: 15), that is, a relation with which the mind operates: it is such that it “produces an union among our ideas” (T: 94). It is because causation is a natural relation that “we are able to reason upon it, or draw any inference from it” (T: 94).³ This last observation is very important to Hume because causal reasoning seems to be somewhat the analogue of demonstrative reasoning when it comes to matters of fact. As demonstrative reasoning extends our knowledge beyond what is immediately given in intuition (cf. T: 70), so causal reasoning seems to extend our knowledge beyond what is immediately given in experience.

It would be wrong, however, to think that Hume’s only aim was to explain the nature of causal reasoning. His project has two aspects, as he thinks we can approach causation in two ways: as a “philosophical” relation and as a “natural” one. It can be argued that analysing causation as a “philosophical relation” aims to unravel what can be legitimately said of causation as it is in the objects, whereas treating it as a natural relation aims to unravel the feature of causation in virtue of which it is involved in reasoning. These two aspects of his project will lead to his two definitions of causation (see section 1.9).

1.3 Impression hunting

One major constraint of Hume’s account of causation is his empiricist epistemology. The cornerstone of this epistemology is the thought that “all our ideas, or weak perceptions, are derived from our impressions, or strong perceptions, and that we can never think of any thing we have not seen without us, or felt in our own minds” (A: 647–8; cf. also T, 4). Let’s call this the Basic Methodological Maxim. Put in a nutshell, it asserts: no impressions in, no ideas out. Ideas are nothing but “faint images” of impressions “in thinking and reasoning” (T: 1). This is not the place to examine Hume’s theory of ideas. What concerns us is what concerns him vis-à-vis causation: what is the impression of the idea of causation? I...

Table of contents

• Cover
• Half Title
• Title
• Copyright
• Dedication
• Contents
• Preface
• Abbreviations
• Introduction
• I Causation
• II Laws of nature
• III Explanation
• Notes
• References
• Index