Making Sense of Level-Relative Causation Alastair Wilson Monash University & University College, Oxford alastair.wilson@monash.edu
Plan • The causal exclusion problem. • The level-relativization response. • Worries about level-relativization by fiat. • Locating the context-sensitivity in events. • Level-relativity and downwards exclusion. • Comparison with level-relativity of chance. • The source of the level parameter.
A simple causal exclusion problem • (1) Distinctness: Mental event types are distinct from physical event types. • (2) Completeness: Every event has a physical event as a cause. • (3) Efficacy: Mental events can be causes. • (4) No overdetermination: The effects of mental causes are not systematically overdetermined. • (5) Exclusion: No event has (at a particular time t) more than one cause unless it is overdetermined.
Level-relative causation • If causation is level- relative, then ‘A caused X’ could be true relative to level 1, and ‘B caused X’ could be true relative to level 2. • So an action could have a mental cause relative to one level, and a physical cause relative to another level. • The level is – somehow or other – supplied by conversational context.
How level-relative causation helps • Exclusion is false: ‘A caused X’ and ‘B caused X’ can both be true, even if A and B are distinct. • But in its place we have: – L-Exclusion: No event has (at a particular time t and at a particular level L ) more than one cause unless it is overdetermined. • L-Exclusion arguably captures the motivations for Exclusion, and it is compatible with 1) - 4).
Level-relative causation by fiat • The simplest way to allow for level-relative causation is via a brute-force approach. • When we assert ‘A caused B’ the level is filled in by a primitive element of context, to go along with the time and world of utterance. • Terence Horgan, inter alia , seems to endorse this view. • But by itself it looks much too cheap.
Problems with level-relativization by fiat • Brute-force relativization strategies are worryingly generalizable. • There is no obvious semantic mechanism by which a level is contextually supplied. • There is no obvious account of how levels themselves are individuated. • Consequently, the strategy looks ad hoc . • Can we do better?
Context-sensitive cause-ascriptions • According to contextualist strategies, ‘the cause of X’ is a context -sensitive expression. • So both of these sentences can be true, in different contexts: – ‘My hunger was the cause of my eating of the banana.’ – ‘The microphysical state S of my brain was the cause of my eating of the banana.’
Where is the context-sensitivity located? • Most extant versions of the level-relativity strategy locate the context-sensitivity in ‘causes’. • ‘Causes’ really means ‘causes according to model X’, ‘causes X -ly ’, or something similar, with parameter X supplied by context. • I have a different suggestion – locate the context-sensitivity in the event descriptions.
Individuating events • How my eating of the banana is individuated is a context-sensitive business. • Identity criteria for events can contextually vary in their fineness of grain . • This leads to contextual variation in degree of specificity for events. • Highly specific events have few possible realizers; highly unspecific events have many.
Causation and degrees of specificity • The same-level requirement : cause and effect should match in their degree of specificity. • Examples: – My hunger caused my eating of the banana. – My ‘hunger neurons’ firing caused my physiologically-specific eating of the banana. – My microphysical state S caused my microphysically-specific eating of the banana.
The modesty of level-relativity • The sort of level-relativity just described results from contextual variation in identity- criteria for events. • For some, this will not be a very interesting kind of level-relativity. • But it does make the truth-value of causation- ascriptions contextually variable, and seems to offer a response to the exclusion problem.
The downwards exclusion response • Menzies & List [2009], amongst others, argue that Exclusion is compatible with Efficacy. • This is because some instances of exclusion are in the downwards direction: the mental cause excludes any physical cause. • This occurs if the causal relation is realization- insensitive : if the effect would still have occurred were the cause differently realized.
How a mental cause can exclude a physical cause • This counterfactual is true: – Had I not been hungry, I would not have eaten the banana. • But this counterfactual is not true: – Had I not been in (micro-physically specific) state S, I would not have eaten the banana. • Had I not been in S, I would still have been hungry, so would still have eaten the banana.
A case of overdetermination? • If Menzies and List are right, then Exclusion is compatible with the causal-explanatory autonomy of the special sciences. • Does this render level-relativity redundant? • I will argue that the downwards exclusion response and the level-relativity response are in fact complementary to one another.
Consequences of downwards exclusion • The premise of the exclusion argument which the downwards exclusion response rejects is: – (2) Completeness: Every event has a physical cause. • Rejecting Completeness is supposed to be compatible with physicalism because supervenience on the physical is maintained. • But it looks like a potential cost.
How to uphold Completeness • Completeness: Every event has a physical cause. • M-Completeness: Every event has a physical cause at the microphysical level . • L-Completeness: Every event has a physical cause at every level . • The level-relativity response requires us only to give up on L-completeness.
Downwards exclusion and level- relativity as complementary • At each level of specificity, an effect has a single cause (unless it is overdetermined). • But which matching cause-effect pair is picked out by a true sentence of the form ‘A caused B’ is a context -sensitive matter. • This combination allows us to preserve both the causal closure of the physical and the causal autonomy of the mental.
What caused my eating of the banana?
The ‘exclusion problem’ for chance • Chance-Exclusion: No event has (at a particular time t) multiple distinct objective chances. • Chance-Exclusion entails that if fundamental physics were deterministic, special sciences couldn’t project non -trivial objective chances. • But chances are ubiquitous in special sciences. • This invites a level-relativization manoeuvre.
The Principal Principle “Let C be any reasonable initial credence function. Let t be any time. Let x be any real number in the unit interval. Let X be the proposition that the chance, at time t, of A’s holding equals x. Let E be any proposition compatible with X that is admissible at time t. Then C(A/XE) = x.” Lewis [1980]
Characterizing admissibility “Admissibility: Propositions that are admissible with respect to outcome-specifying propositions A i contain only the sort of information whose impact on reasonable credence about outcomes A i , if any, comes entirely by way of impact on credence about the chances of those outcomes.” Hoefer [2007]
Lewis on admissibility • Lewis [1980]: all historical information, plus information about the laws, is admissible. • This prevents probabilities in special-science theories from counting as chances: – Probabilities in classical statistical mechanics. – Probabilities in Bohmian quantum mechanics. – Probabilities of being dealt a specific hand in a poker game.
Relativizing admissibility • Admissibility is relativized to degree of fineness of grain of description: – In statistical mechanics, information about the exact microstate of the system is inadmissible – In Bohmian quantum mechanics, information about the positions of corpuscles is inadmissible. – In poker, information about the order of cards in the deck is inadmissible.
Level-relative causes from chances? • Causation might inherit a level parameter from chance, if chance features (directly or indirectly) in the analysis of causation. • Or the level parameter might derive from resources featuring in the analysis of both causation and of chance. • Either way, a unified account of level-relativity for chance and causation would be appealing.
A level parameter from chances – directly? • The most straightforward way to get level- relative causation from level-relative chances is via a probabilistic analysis of causation. • Appropriate probabilistic analyses of causation might include those of: – Kvart [2004] – Glynn [2010]
A level parameter from chances – indirectly? • Various theories incorporate objective chances into the semantics of counterfactuals. • Given such theories, counterfactuals could inherit a level parameter from chances. • And given counterfactual difference-making theories of causation, cause ascriptions in turn could inherit a level parameter from counterfactuals.
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