CAUSATION. I. Initial distinctions

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1 CAUSATION I. Initial distinctions i) Logic: conceptual analysis of the notion of cause ; definitions of cause (e.g., is temporal priority of causes a priori?) This includes both logical analyses and empirical studies of everyday conceptions of causation. ii) Metaphysics/ontology: the nature of causation and causal relations (vs. other types of relations) iii) Epistemology: inference to and justification for causal claims 1

2 1. Methodology a) Role of everyday examples Hausman: II. Key Questions Ordinary cases of causation are data with which our theories must agree. Humphreys revisionary metaphysics : Our theories should not be bound by ordinary language (esp. for probabilistic causation which is quantitative, since ordinary language is oriented towards deterministic cases which are qualitative) Horwich: Quinean holism b) Role of scientific examples Even Humphreys takes these as data c) Role of intuitions E.g., transitivity E.g., necessary connection Hume (on necessity) is our model: Where intuitions are not preserved by a theory, the illusion has to be explained away. d) Pluralism: one theory or many? 2

3 2. Are deterministic and probabilistic causation fundamentally different? Deterministic: eclipse Probabilistic: weed killer, smoking 3. Are type and token causation fundamentally different? Type: smoking causes lung cancer Token: John s smoking caused John s lung cancer Argument for distinction (probabilistic case): - smoking may cause lung cancer (type-level) even if no smoker ever develops lung cancer (token-level) - air travel may not cause early death (type-level) even though it causes particular deaths (token-level) 4. What is the role of causality in scientific explanations? Parallel puzzles: a) Asymmetry Position of sun, moon and earth explains eclipse: not vice versa More generally: earlier events explain/cause later events, not vice versa b) Spurious correlation - hexed salt//birth control pills - barometer//storm These parallels suggest that causation and explanation are fundamentally related. - Are all explanations based on causal relations? - Do all causes give rise to explanations? - If explanation is pragmatic, could the same thing be true of causal relations? 5. Can causal claims be inferred from statistical data? Spurious correlations show that positive statistical relevance is not always the same as a genuine causal relation. 3

4 III. Hume s account Starting point for all modern theories of causation: - variants of Humean account are still in the running - problems faced by Hume s account are problems faced by all accounts 1. Empiricist framework Hume s principle (p ): Trace each idea to its impression (if simple) or to some complex combination of ideas that derive from impressions (via the principles of connection). Motivation: sceptical -- subvert abstruse philosophy and metaphysical jargon. (cf. Section on miracles.) 2. Definition(s) of causation (pp ) Three different definitions (all on 51): a) a sufficient condition b) a necessary condition (expressed counterfactually) c) a psychological definition Common core: A causes B iff A and B are things (singular causation) such that: i) Regularity: There is a regular association (or constant conjunction) between things similar to (of type) A and things similar to B ii) Temporal priority: A precedes B Treatise adds: iii) Contiguity: A and B are contiguous (in space and in time) But this is dropped in the Enquiry (mental causation). The first definition represents the regularity condition in terms of sufficiency of cause to produce effect. The second definition represents the regularity condition in terms of necessity of cause to produce effect. The third definition adds regularity of mental association between cause and effect. 4

5 3. What about necessary connection? Cause and effect are conceptually independent (billiard ball example, p. 18): section IV, and a more detailed study in section VII. VII (p. 41ff): there is no impression of necessary connection, so it is not part of causation itself that there be such a connection However, the habit of passing from cause to effect yields the feeling of necessary connection. Canvasses possible sources for such an impression: external objects, bodily actions, internal objects (mental operations) and finds none. The point is familiar to us, but evidently not to Hume s audience, since he makes some interesting arguments here (dependent upon the idea that if we had an impression of the causal relation, we would know the relata). 4. Virtues of Hume s account: - explains connection between causes and regularities - takes (some of) the mystery out of causation: the necessary connection is purely psychological 5

6 5. A closer look at the definitions Temporal priority - obvious to Hume (not justified in the Enquiry) - simply stipulated - what of simultaneous causation or reverse causation? Contiguity - Included in the Treatise, omitted in the Enquiry - would rule out remote causation (action at a distance) or indirect causation via a chain of intervening causes and effects Modified form: Direct causes are contiguous. Indirect causes are defined by an intervening sequence of direct causes. Regularity: Objects similar to A are invariably followed by objects similar to B: a sufficiency analysis. Problem 1: Vagueness of similarity. Remedy: Appeal to laws. (x)(ax Bx) must be a law (or derived from laws), where A and B are kinds. Problem: distinguishing laws from accidental regularities. Problem 2: causes are not invariably followed by their effects. Example: Shooting causes death; watering causes growth; even dropping a coin causes it to fall --- these are not invariable. Hume himself acknowledges this (pp. 73-4). Remedy 1: partial causes. Often isolating causal factors is our goal, even though not sufficient to guarantee a result. But this still does not handle indeterministic cases. Our best theories suggest that the world may not be deterministic, so we should not require such a guarantee unless we want to give up most causal claims. [We can waive this objection if we focus on deterministic cases.] Probabilistic causation is foreshadowed by Hume (37; 73-4), though the probabilities are epistemic artefacts (the produce of ignorance), rather than genuine chance (37). 6

7 Problem 3: Spurious correlations undermine causal claims. (Thunder/lightning) Problem 4: Redundant causes (a problem for necessity analysis). Overdetermination cases: multiple bullets hit the target (a problem for the necessity condition). Preemption cases: Lewis: one enemy poisons the water, the other puts a hole in the can: the water leaks out and the traveller dies of thirst. Poisoning the water is the pre-empted condition Putting a hole in the can is the pre-empting condition Correct view: the hole is the cause. But on a necessity analysis, neither counts as a cause (since neither condition is necessary, given the other). 7

8 IV. Russell Main Thesis: The law of causality is either confused or false, and in any case not needed or used in science. 1. Dictionary definitions 1. Causality = necessary connection of events. Necessity = (roughly) truth under all circumstances. What varies is the time of the event. Thus the principle of causality becomes: (PC) Given any event e 1, there is an event e 2 and a time interval τ, such that whenever e 1 occurs, e 2 follows after an interval τ. (Must construe e 1 as an event-type.) 2. Cause = included in the thought or perception of a process as taking place in consequence of another process This is really an effect; but in any case, it is rejected as psychological and as pre-supposing causality (in the idea of consequence). 3. Cause and effect = two things so related that whenever the first ceases to exist the second comes into existence immediately after, and whenever the second comes into existence the first has ceased to exist immediately before. Roughly: Temporal contiguity + regularity + time order Problem: contiguity in time is impossible [Russell s argument succeeds only if we assume the cause must have duration] But if we drop contiguity, we have roughly Hume s (Enquiry) analysis, with the regularity condition interpreted as both sufficiency and necessity of cause to produce the effect. 8

9 2. Substantive Objections 1) What is meant by an event? - a broadly defined universal (event-type), else not repeatable 2) How long a time-interval separates cause and effect? Leads to a dilemma: if we omit the environment, something could intervene so that the cause is not sufficient to guarantee the effect if we include enough of the environment so that the cause is sufficient, then the cause is specified too narrowly (and becomes one of a kind) [Why not consider an amended interpretation of the regularity condition?] 3. Alternative picture of science The principle arose due to experience of invariable uniformities. This led to the formulation of the Principle of Causality (PC): same cause, same effect. But (PC) is much too crude: all such generalizations are likely to be high-level and relatively imprecise. Science does not aim at discovering nothing but crude, high-level universal generalizations: - Crude uniformities may be useful early on, but mature sciences aim at more informative and nuanced quantitative laws (e.g., law of gravitation) - Also: complex, well-specified particular configurations of causes are unlikely ever to recur 9

10 4. Misleading ideas about causation i) Cause and effect resemble each other. Aristotle: transfer of form (Cf. Descartes principle: more sophisticated version) ii) Intelligible nexus between cause and effect. - modeled on volition: but volition is mysterious * no place or need for such a nexus in physics [One of the strongest arguments for a Humean or neo-humean account: who needs more than regular conjunction, so why posit more? Cf. p. 186: science will assume what the case requires, but no more ] iii) Cause compels the effect, but the effect does not compel the cause. OR Cause determines the effect, but the effect does not determine the cause. Note: an effort to capture the asymmetry. Determines = a functional relation. Given the causes one effect Given the effect many possible causes Russell: this claim is false; the asymmetry is an illusion [This is a KEY part of his essay, but it is not drawn out. Laws do NOT exhibit asymmetry, but causality DOES. So to supersede causality, the appearance of asymmetry has to be explained away. Does Russell do this?] iv) A cause cannot operate when it has ceased to exist. (Temporal contiguity) Russell: causes don t operate at all, and in fact are separated by an interval from their effects (thus, they have ceased to exist) v) A cause cannot operate except where it is. (Spatial contiguity) Russell: would rule out any effects removed from the cause [None of these problems makes it seem impossible to clean up the notion of causation.] 10

11 5. Modified principle of causality Notes: An event of type A causes an event of type B if A s have been invariably followed by B s. 1) The principle of induction licenses an inference to a probable connection (rather than an invariable or necessary one) between cause (A) and effect (B) in such a case. And that is all that is meant by a cause. 2) Abandon universal claim that every even has a cause in this sense (there are some rather improbable events, for instance). 3) Any sequence that satisfies this condition counts as a cause-effect relation (e.g., night causes day). [Russell also drops the requirement of invariability.] 4) Such laws will eventually be replaced by quantitative laws (e.g., law of gravity). There is no cause and effect in an explanation of planetary motion. These laws are symmetric in time and place. [Is there no asymmetry? Can we explain the sun s position using the earth s and the moon s at the time of an eclipse, or are we just deriving it?] Features of the modified principle i) Status: a posteriori. ii) Determination is a time-symmetric relation iii) Uniformity of nature is accepted on weak inductive grounds: laws tend to be permanent. 11

12 6. Isolated systems S is relatively isolated over some time period if it will behave the same way however the rest of the universe is constituted. S is practically isolated if there might be states of the rest of the universe that would alter its behaviour, but we have reason to believe that these states do not occur. - We can t know in advance that a system is isolated - Only in an isolated system can we discover scientific laws The paradigm case of causation, A causes B, is only the very special simple case of a practically isolated system. 7. Deterministic systems Causality s main epistemological role: showing the possibility of inferring future states or events from past states or events. A system is deterministic if there is a formula which tells us the state of the system at any time, given some finite number of states of the system at different times. But this is just a logical relation, there is no mysterious necessary connection here. Illustrations: mind and matter; mechanism and teleology Dismisses another asymmetry: between past and future. Discussion culminates in the idea that no scientific law can involve time as an argument. 8. Application to free will 12

13 V. Horwich 1. The problem of causal order linked concepts: causation, explanation, law of nature, counterfactual Question: Why do effects rarely, if ever, precede their causes? Why is the predominant (perhaps only) direction of causation from past to future? Puzzle: causation appears to be a type of determination relation; all determination relations (e.g., derivability from state + laws of nature) appear to be time-symmetric. Reply: causation is determination plus something else that gives us priority of causes. 1. Conventional predetermination: (a) time order is an a priori part of the definition of causation (Hume) (b) the belief that causes precede their effects is a priori 2. Substantive accounts: (a) some contingent facts constrain the time order (by generating the direction of causation) (b) Our belief that causes precede their effects is a posteriori, based on knowledge of these contingent facts Horwich s account combines 1a) and 2b): the direction of time is explained by the fact that time order is a constituent of causal relation, but this fact is a posteriori. concept of causation: pre-philosophical beliefs about causation theory of causation: a systematization, simple specification and explanation for these beliefs Horwich will propose a neo-humean theory of causation in which temporal priority is basically constitutive of causation. But the grounds for believing this theory will be a posteriori, not a priori: they will be drawn from our concept of causation, which is experiential. Remarks: 1. Begin with the conventional predetermination view, but a more sophisticated formulation than just appending X precedes Y to a determination relation. 2. Horwich follows Quine in suspecting that there is no pure a priori in any case, so it s important to see the proposed theory as a posteriori. 13

14 Question: Does this lead to an entirely superficial answer to Horwich s original question: Causes precede their effects because that is the nature of causation in our world.? Experience a posteriori concepts of causation a neo-humean theory in which causes precede their effects. 14

15 2. Neo-Humean account Hume: C causes E if a) C precedes E <temporal priority> b) C is contiguous with E <contiguity omitted in Enquiry> c) Events like C are always followed by events like E <regularity> Here, regularity is presented as sufficiency of C for E, but Hume s other version in the Enquiry is in terms of necessity. Problems and remedies: 1) Failures of contiguity. [Ex: Garage door opener] Remedy: define direct and indirect causes (which allow for causal chains) < Hume s own modification.> 2) Accidental regularities. [Ex: Smith struck by lightning every time he leaves bank with $666.] Remedy: regularities must be laws (left unclear). 3) Less than constant conjunction. [Ex: Car starts nearly every time I turn the ignition.] Remedy: only the total cause is invariably followed by the effect, but a part of the total cause still counts as a cause. 4) Vagueness of similarity. Any two things are similar in some way. Remedy: Use characteristics relevant to basic laws of nature. (cf. Goodman s notion of entrenched predicates.) Note that remedies 2 and 4 are merely shifting the bump under the rug, not solving the problems. But the problems plague every theory of causation. So we end up with: i) C is a direct cause of E if C is an essential part of an antecedent condition whose description entails, via a basic law of nature, that E will occur. ii) C is an indirect cause of E if there is a causal chain E 1, E 2,, E n such that E i is a direct cause of E i+1, and C = E 1 and E = E n. (Note: could also be a continuous chain.) Picture of direct vs. indirect causation: Interpolate a series of determining events between C and E. The relations between the intermediate events E i, E i+1 become more and more basic: in the limit, must be basic laws. These constitute the elementary links in the chain. [Note: the definition does require amending somewhat in the continuous case: there is no next point.] 15

16 Virtues of the account: 1) Distinguishes spurious correlation ( epiphenomena ) from causation Ex: barometer/storm 2) Handles simultaneous causation. Ex: pushing; house of cards Appears to be precluded by conventional predetermination theories. Remedy: 1) Replace temporal priority requirement for direct causation with prior or simultaneous. 2) Assign directions of causation (represented by arrows) so as to maximize causal continuity in the whole chain. Upshot: avoid adjacent links with arrows in opposite directions as far as possible. [Again have a problem for the continuous case, where there are no adjacent links.] Assuming that the diagram is connected and contains at least one nonsimultaneous, should prescribe a unique causal interpretation. [Note: still have some puzzling cases, such as this one: What direction do we assign to the two simultaneous causes? The continuity condition does give the right answer here. But in the diagram below, there is no obvious way to decide between both inwards, both left, both right and both outwards: all yield 3 discontinuities. 3) Backward causation is ruled out, but not a priori. [But not explained: p. 138.] 16

17 What about probabilistic causation? Some causes involve effects that are not deducible from (determined by) their causes. Two ways to go: A) Two distinct varieties of causation: deterministic and probabilistic. B) A weaker theory of causation that accommodates both cases. C is a direct cause of E if the description of C together with initial conditions and how certain indeterministic factors turn out entail, via a basic law of nature, E. Just expand the total cause to include the result of the indeterministic processes. [Big problem: this says nothing about whether C is a contributing cause! Regular exercise might cause a heart attack, because there is a statistical law that incorporates exercise, diet, cholesterol, etc] 17

18 3. Manipulation Objection to conventional predetermination theories: don t explain why rational actions are intended to cause a desirable outcome. Why not retro-cause, or retro-determine? Reply: There is no such rationality requirement, but we can still explain the rarity of situations in which acting for the sake of the past would be rational (e.g., Newcomb cases). Rough idea: such an act would only be possible if we believed it were needed to retro-cause the desirable past state; but most of the time, we know either that the past state obtained or did not obtain (so either unnecessary or not sufficient). And in Newcomb cases, it is rational to act for the sake of the past. {???} [Objection: What about medical Newcomb cases?] Manipulability theories (week 4): C causes E C could be used as a means for producing/controlling E Thompson: pre-supposes causality. There could be an action W that causes C and C causes E. Horwich s view is that manipulability is part of our fallible, reference-fixing concept of causality, not suitable for a theory of causality. A defeasible part of our conception (e.g., in Newcomb cases). 18

19 4. Why believe that causes precede their effects? There are many routes to this belief, all passing through our fallible conception of causality: i) manipulability maxim: causation is the relation between rational choices and the events for the sake of which those choices are made. {Most (all) such choices are future-oriented.} ii) prevalence of normal (future-oriented) conjunctive forks, rather than inverse (past-oriented) forks. Horwich is happy if there are many such empirical bases for our belief that causes precede their effects, since he has a Quinean holistic picture of justification. So we could, if inverse forks suddenly started to appear, change our minds. 19