20th World Congress of Philosophy Logo

Philosophy of Mind

Simulation, Folk Psychological Explanation,
and Causal Laws

Angela J. Arkway
New York University

bluered.gif (1041 bytes)

ABSTRACT: The assumption that commonsense psychological explanations of behavior are causal underlies current debate between simulation theory and theory theory regarding the nature of cognitive mechanism responsible for our folk psychological practices. Theory theorists claim that these explanations are subsumed by the covering law model of causal explanation. Simulationists are not explicit about the nature of the explanations produced by simulation. In what follows, I propose a set of plausible conditions that a correct causal simulation-produced folk psychological explanation will satisfy and point out two prima facie problems. In discussing a possible solution, I discover that the latter incurs the need for some sort of causal law. An examination of two likely candidates for these laws reveals that neither is capable of playing the role required. I then suggest alternative routes that simulationists might explore in order to provide simulation theory with a sorely-needed account of the nature of the explanations produced by simulation.

bluered.gif (1041 bytes)

I. Introduction

Much interest has been raised recently in cognitive science and in the philosophy of mind by a debate that focuses on the nature of the cognitive mechanism that underlies our folk psychological practices. One side in this debate is represented by proponents of the reigning paradigm, the theory theory. Theory theorists say that our ability to give explanations, predictions and interpretations of intentional behavior is subserved by tacit knowledge of an internally-represented theory of commonsense psychology (Fodor 1987). The simulation theory challenges this view on the grounds that there is no evidence to support the suggestion that we have such knowledge and some evidence to suppose that we do not (Gordon 1986: Goldman 1989). It is more likely, say simulationists, that these abilities are simply underpinned by the innate capacity to simulate others.

Simulationists argue that a compelling case can be made against the theory theory. I do not discuss that case here. Instead I address an issue which, although crucial to the outcome of the debate, has not yet been examined. This issue concerns the nature of the commonsense psychological explanations produced by the mechanism whose functioning both theories claim to describe.

Two assumptions bring the issue of explanation to the fore. One of these pertains to the range and the other to the type of event that the theories are adduced to account for. The merits of the theory theory and the simulation theory are usually discussed in relation to the practice of the prediction of intentional behavior. The reasonable assumption, (assumption A), is that the mechanism that is deployed in prediction will be the same one that is deployed in the explanation, the description and the interpretation of our own and others’ behavior. The second assumption, (assumption B), is that the two theories offer competing accounts of the same sort of event. The theory theory and the simulation theory, in proposing alternative views of the mechanism underlying our folk psychological practices of prediction, explanation, etc., agree on what these practices consist in.

With regard to explanation, the grounds for assumption B are not clear. Theory theorists hold that the commonsense psychological explanations of behavior produced by theory deployment are causal explanations. Those who think that the folk theory is internally represented in the form of psychological laws have a ready-made model of causal explanation available to substantiate this claim, the covering law model. Just like explanations in basic science and in the special sciences, they point out, folk psychological explanations are deductive arguments in which a commonsense psychological covering law is implicitly deployed.

Simulationists are not explicit about the kind of explanations produced by simulation. Nevertheless grounding assumptions A and B requires spelling out the conditions that a correct simulation-produced folk psychological causal explanation of behavior satisfies. Since the simulation theory is founded on the premise that there is no body of internally-represented commonsense psychological knowledge, and consequently no laws in which it is represented, appealing to the covering law model in the same way that theory theorists do is not an option. What simulation needs in order to substantiate assumptions A and B is a causal account of folk psychological explanation whose satisfaction conditions either involve simulation essentially or, if they do not, are at least compatible with simulation as an heuristic device for picking out what is the most likely to be the correct explanation. In this paper I discuss a suggestion for explanation which assigns an essential role to simulation.

In the next section, I propose a set of simulation-involving necessary and/or sufficient conditions for a correct causal folk psychological explanation and point out two prima facie problems with it. In the section after that I discuss a plausible solution to these problems and discover that this solution incurs the need for some kind of causal law. After an examination of two likely candidates for these laws in Section Four, I suggest, in the final section, alternative routes that simulationists might explore in order to provide the simulation theory with a sorely-needed account of the nature of the explanations produced by simulation.

II. The Simulation Theory, Explanation, and Relevance

A theme common to most versions of the simulation theory is that when we predict the behavior of another person, or of ourselves at a time remote from the present, the practical-reasoning mechanism is disengaged from its actual inputs — occurrent external stimuli and salient beliefs and desires, and from the action controllers, the mental mechanisms responsible for a decision-to-behave being translated into actual behavior. Operating "off-line" in this manner, the decision-making mechanism is fed pretend-input in the form of those beliefs and desires we imagine we would instantiate ourselves if we were in the situation of the person whose behavior we are about to predict. These pretend inputs are then processed and a pretend decision-to-behave is generated. The pretend decision-to-behave is transformed into the prediction of behavior. Commonsense psychological explanations of behavior are produced in a similar way, claim simulationists. In explaining a behavioral episode we feed into our disengaged decision-making mechanism those beliefs and desires we imagine are likely to produce a decision to perform the behavior we want to explain.

A plausible suggestion for the sort of conditions satisfied by a folk psychological causal explanation of behavior produced in the manner just described is the following:

(SE) The statement that Oprah went to London because she believed p and desired q is a correct explanation of her going to London iff
(1) she went to London
(2) she believed p and desired q, and
(3) a decision to go to London is the result of a simulation of Oprah run on the explainer’s decision-making mechanism and that simulation satisfies two conditions:

(a) it essentially involves the belief p and the desire q
(b) there are no facts about Oprah such that were the explainer to know them a different decision would result from his simulation of her. (1)

A prima facie problem here, and maybe with regard to any simulation-based conditions, concerns the relation between the goings-on in the explainer’s head and whatever it is that makes an explanation of Oprah’s behavior correct. If, as implied in (3), Oprah is endowed with a decision-making mechanism that essentially involves her psychological states, it seems true that part of what makes the explainer’s statement a correct explanation of her behavior is that the decision to go to London was the result of a decision-making process in Oprah that essentially involved the belief p and the desire q, and the fact that she did go to London. However the notion that whatever else is required in order to make that statement a correct explanation will be something to do with the explainer’s decision-making mechanism is in dire need of an argument. And if relevance cannot be established, then clearly simulation will be neither sufficient nor necessary for explanation.

A second prima facie objection, one that lends support to the objection of irrelevance, is that there are counterexamples to (SE)(3). Let us suppose that "Oprah went to London because she believed that Michael Jackson was there and she wanted to interview him" is the correct explanation of the fact that Oprah went to London. It seems that an explainer could give this correct explanation and at the same time know that if he were in Oprah’s situation with her relevant beliefs and desires, he would not decide to go to London because he believed that Michael Jackson was there and he, the explainer, wanted to interview Jackson. That is, even though his explanation of Oprah’s behavior does not satisfy (SE) because a simulation of her run on his mechanism does not produce a decision to go to London, it is still correct. If this is the case, not only is satisfaction of the simulation condition not necessary for correct explanation but were an explainer to rely on simulation, the correct explanation would probably elude him.

A likely simulationist response to both of these objections is to simply invoke the truism that appearances are often misleading; the goings-on in one person’s head actually are relevant to what it is that makes an explanation of another’s actions correct and the above correct explanation of Oprah’s behavior does satisfy the simulation condition at (SE)(3), whatever appears to be the case. Since our capacity for practical simulation operates at a sub-verbal level most of the time, and since, when simulating, our decision-making system "gets partially disengaged from its ‘natural’ inputs and fed instead with suppositions or images (or their ‘subdoxastic’ or ‘subpersonal’ counterparts)" (Gordon 1986, p.170), successful simulation is necessary for the correctness of an explanation whether or not the explainer is aware of the simulating process or even whether he knows on a personal level that he would not have made the same decision as Oprah had he been in her position.

Decisive empirical evidence about what is going on subpersonally being notably hard to come by, (Harris, 1992: Stich and Nichols, 1992), I restrict my remarks in the remainder of this paper to a conceptual problem that this response to the first and second objections elicits for simulationists.

III. The Threat of Collapse

Martin Davies (1994) points out that simulation runs the risk of collapse into the theory theory under some construals of the simulation procedure. The focus of his comments are the very inputs (personal and subpersonal) that the simulationist response to the first and second objections appeals to.

Davies says that when the inputs to the simulating system are taken to be representational states whose contents themselves concern mental states, contents of the form "I believe that p" and "I desire that q", what will be generated by their processing and then ascribed to the person being simulated is either a conclusion about a further mental state, for example "I believe that r", or a conclusion about an action, "I V", or about an intention to act, "I intend to V" (1994, p.114). Davies agrees with other simulationists that this kind of simulation will count as process-driven, as opposed to theory-driven, if the processing in the simulator is isomorphic to the process being simulated but, he points out, besides being isomorphic, "...the processing in the simulator could also follow the contours of the derivational structure of a proof of a conclusion about, say, the agent’s beliefs and desires — a proof cast in a psychological theory" (1994, p.115). The threat of collapse ensues because it is the idea of the matching of structure between a causal process and a derivational structure that is used in some versions of the theory theory. Furthermore, says Davies, since inputs such as "I believe that p" exhibit the general form "x believes that p", the states of entertaining them are appropriate inputs to a mechanism that embodies tacit knowledge of a psychological theory. He goes on to suggest that by appealing to a different construal of simulation the threat of collapse into the theory theory can be avoided (1994, p.117).

Under this construal, the simulator simulates the mental processing of another by identifying with that other in his imagination. The simulator, instead of imaginatively entertaining hypotheses about mental states, projects himself onto the other and imaginatively adopts what he takes to be the other’s mental states; he imagines believing that p and desiring that q. The states processed by the decision-making mechanism are simply pretend-states with the contents "that p" or "that q" and what is generated is either pretend-beliefs, or a pretend-decision to behave. Processing mechanisms that mediate transitions amongst states with such contents are not going to be embodiments of tacit knowledge of the principles of a psychological theory, says Davies (1994, p.117).

If Davies is right, one way that the simulationist who responds to the irrelevance and counterexample objections by invoking subpersonal simulation can avoid implicit appeal to a tacitly-known folk theory is to construe the simulation referred to in (SE)(3) as identification in the imagination. Let us see what is required in order for that condition to be satisfied under this construal.

IV. Causal Laws

A widespread philosophical assumption is that events related as cause and effect fall under causal laws. So it is incumbent on theorists who hold that folk psychological explanations explain behavior in terms of its causes to either say what kind of causal laws there are that subsume mental states and link them to behavior, or alternatively, and more radically, to debunk that assumption by suggesting a causal account of folk psychological explanation that does not appeal to psychological laws. In the remainder of this paper I explore the first option by discussing two likely candidates for laws. In a paper entitled "The Simulation Theory and Explanations that ‘Make Sense of Behavior’" I discuss the alternative solution.

It is important to note that an appeal to psychological causal laws on the identifcation-in-the-imagination reading of simulation does not entail the collapse of the simulation theory into the theory theory. The theory theory is usually described as an internally-represented body of information. In the case at hand the posited background causal laws are not internally represented or tacitly known. They are laws which are just assumed to exist. If one finds the explanation of folk physics "the window broke because it was hit by a rock" an acceptable commonsense causal explanation of the fact that the window broke, and holds that this is so because there are unknown background laws which subsume these events, then there is no reason to deny that there are unknown underlying laws in the folk psychological explanation "Oprah went to London because she believed p and desired q." .

The most likely candidates for these unknown causal laws are intentional ceteris paribus (cp) laws, laws of the form

[1] (p)(q)(if one believes p & believes [that if p, q], then, cp, one believes q).

There is, however, a standing argument against the existence of laws of this type. Stephen Schiffer (1991) points out that although psychological cp sentences might express true propositions it is doubtful that these propositions are, or determine, anything that could play the role of psychological covering law in a folk psychological explanation of behavior. In discussing the nature of the propositions that psychological cp sentences express Schiffer first considers the suggestion that the cp clause can be cashed in the vocabulary of intentional psychology.

[2] (p)(q)(if one believes p & believes [that if p, q], then - barring confusion, distraction, etc. — one believes q). (Churchland 1981, p.71)

Schiffer remarks that in a human being the psychological states referred to in the antecedent of this conditional are realized by brain states and their interaction accounted for by defeasible physical mechanisms. The important question, he says, is; "Will every nomologically possible physical defeater of these physical mechanisms itself realize a psychological state, such as confusion, irrationality, or distraction, that could take its place in a wholly psychological true completion of [2]?" (1991, p.4). The most plausible answer is no, says Schiffer. Neither commonsense nor scientific psychology has had great success in cashing cp clauses and empirical evidence from brain-damaged people seems to indicate that there are breakdowns in normal cognitive processes that cannot be accounted for in purely psychological terms.

Schiffer also considers the possibility that cp sentences can be completed in the vocabulary of a more basic science (Fodor 1987, p.6). The idea is that psychological cp laws, although expressed in purely intentional terms, have implementing physical mechanisms that underpin them and which are referred to idiomatically by the cp clause. Schiffer suggests that a plausible way to interpret this view is to see the antecedent of the conditional as constituted by a conjunctive condition, one conjunct of which describes a psychological condition and the other (say) a neurological condition. Thus,

[3] (p)(q)(EC)(C is a condition specifiable in the language of neurology & it’s a law that if (one believes p & believes [that if p, q]) & C is satisfied, then one believes q. (Adapted from Schiffer 1991, p.5)

In this case the satisfaction of both conjuncts of the antecedent of the conditional embedded in [3] will be causally sufficient for the satisfaction of the consequent although the satisfaction of neither conjunct alone will be. Schiffer points out this suggestion is coherent only on the understanding that, for example, in the case of the human organism, it is a neurological realization of the psychological condition that conjoins with the implementing neurological condition to make a causally sufficient conjunctive condition for the occurrence of event subsumed by the consequent. He argues that in this case the proposition expressed by the conditional would not be true. Since the only requirement on being a realization of a psychological state is that it have a certain functional role and that it stand in a certain relation to distal objects and properties, it is easy to imagine realizations that can cohere with the basic neurological condition and not form with it a causally sufficient condition for the occurrence of the behavior. For a proposition which specifies this kind of a conjunctive sufficient condition for behavior to be true, what would need to be shown is that every physically possible realization of the psychological conjunct of the condition that could cohere with the unspecifiable, but nevertheless specific, neurological condition would form with it a sufficient condition for the behavioral event to occur. After modifying [3] so that it will accommodate this problem, Schiffer points out that what is left does not warrant talk of a psychological cp law that could play the role of covering law in a commonsense explanation of behavior (1991, p.7).

A second candidate for the causal laws that subsume psychological states are laws of a type which, were they knowable, could not be expressed in intentional terms. The neurological properties of the states referred to in our folk psychological explanations might be subsumed by unknown neurological causal laws and the latter be what accounts for their correctness.

Let us see how this would work in the explanation of Oprah’s behavior. Let us suppose that one of the events that occurs in the causal chain between the neurological events that are the belief and the desire about Jackson, and the behavior, is a neurological event which happens to be a crazy intention to go to London just for the hell of it. In this case the explanation that Oprah went to London because she believed Jackson was there and wanted to interview him is false even though the neurological events that underpinned that belief and desire were part of the causal chain whose final link was the event that was her going to London and even though those events are subsumed by a strict causal law. The fact is that whereas the belief, the desire and the intention were all causally related by virtue of their neurological properties to the decision to go to London, only the intention to go just for the hell of it played an explanatory role in relation to that decision. (2)

So it looks as though the states referred to in our folk psychological explanations being subsumed by physical causal laws is not sufficient to account for the correctness of those explanations. What is needed is a condition on explanation that weeds out what it is that is explanatorily relevant about a state or event in relation to another state or event from what it is that is explanatorily irrelevant. It does not appear likely that a simulation-based condition will be up to performing this task. For even if the explainer were to succeed in simulating all of the specifically-weighted inter-related complex of mental states that is causally relevant to Oprah’s behavior it is no more likely that the intentional states selected by the explainer will be those that are actually explanatorily relevant to Oprah’s behavior than any of the others that are causally related to the decision to behave and that he has successfully simulated.

V. Conclusion

I have pointed out that in order to substantiate two assumptions underlying the simulation-theory theory debate simulation needs a causal account of folk psychological explanation. The focus of my discussion has been a suggestion for an account which assigns an essential role to simulation. It turns out that an interpretation of this suggestion that avoids implicit appeal to an internally-represented theory incurs the need for causal laws. My discussion of two plausible candidates for these laws revealed that it is unlikely that either can play the role required. Considering other, less likely, candidates however is just one way that simulationists can continue the search for a simulation-based account of folk psychological explanation.

A different approach is to explore the possibility of a causal account of commonsense explanation that involves simulation essentially but does not appeal to laws of any kind. The suggestion put forward by Martin Davies and Tony Stone (1996), and, in another place, by Jane Heal (1996), that simulation-produced explanations "make sense of another person" by citing the thoughts important to determining his/her behavior on a particular occasion is a likely candidate for this sort of account. I discuss their proposal in this light in the paper mentioned earlier. Yet another course is to assign a weaker role to simulation in explanation. In this case the aim might be to find a causal non-law-based account of explanation that attributes a non-essential role to simulation, maybe the role of a mere heuristic device.

Perhaps the most radical move that simulationists might make is to argue that the theory theory is mistaken; folk psychological explanations do not explain behavior in terms of its causes but in a different sense, maybe in the sense of providing some sort of understanding to the explainer. If this is what simulationists have in mind, then just as for Collingwood, Dilthey and the Verstehen theorists who argued this case against the logical positivists, the burden of proof is on the simulationist side.

bluered.gif (1041 bytes)


(1) I am indebted here to Hartry Field for his suggestions.

(2) The importance of this point was impressed upon me by Stephen Schiffer.


Churchland, Paul. 1981 Eliminative Materialism and Propositional Attitudes. Journal of Philosophy,78, 2. 67-90.

Davies, M. 1994. The Mental Simulation Debate. In C. Peacocke (ed.), Objectivity, Simulation and the Unity of Consciousness: Current Issues in the Philosophy of Mind: Proceedings of the British Academy, 83. Oxford University Press: Oxford. 99-127.

Davies, M. and T. Stone. 1996. The mental simulation debate: a progress report. In Peter Carruthers and Peter K. Smith (eds.), Theories of theories of mind. Cambridge University Press: Cambridge. 119-137.

Fodor, J. 1987. Psychosemantics. MIT Press: Cambridge Goldman, A. 1989. Interpretation Psychologized. Mind and Language,4, 165-82.

Gordon, R. 1986: Folk Psychology as Simulation. Mind and Language, 1, 158-71.

Harris, P. 1992. From Simulation to Folk Psychology: The Case for Development. Mind and Language, 7, 120-44.

Heal, J. 1996. Simulation, theory, and content. In Peter Carruthers and Peter Smith (eds.) Theories of theories of mind. Cambridge University Press: Cambridge. 75-89.

Schiffer, S. 1991: Ceteris Paribus Laws. Mind, 100, 1-17.

Stich, S. and S. Nichols. 1992: Folk Psychology: Simulation or Tacit Theory? Mind and Language, 7, 35-71.

bluered.gif (1041 bytes)


Back to the Top

20th World Congress of Philosophy Logo

Paideia logo design by Janet L. Olson.
All Rights Reserved


Back to the WCP Homepage