aren’t relevant to the question of how a simulation routine actually works.
Recall my distinction, at the end of section 1.2, between descriptive and normative epistemology. Jackson and others who invoke the foregoing ar-gument seem to draw a descriptive conclusion from an (epistemologically) normative assumption, a type of move I have disavowed.7
It is true, of course, that there must be some delimited class of objects to which attributors apply the simulation heuristic. They don’t apply it to rocks, for example. Mustn’t the chosen targets have some properties or other, on the basis of which attributors decide to treat them as minded, more specifically, as objects to which the simulation heuristic is applicable? Yes, this seems right.
But it isn’t clear a priori that the characteristic in question is resemblance-to-self. Moreover, resemblance-to-self doesn’t seem to be a characteristic that invokes any psychological law. The critic seeks to show that the simulation heuristic, when fully described, requires a tacit belief by the attributor in a folk-psychological law. But what is the believed law? Presumably, it is ‘‘All objects of such-and-such a sort [that is, the ones to which I apply the simu-lation heuristic] are similar to me.’’ But this isn’t a folk-psychological law of the sort TT posits. Laws in the TT mold are intrapersonal, diachronic laws, describing mental state transitions within an individual (or perhaps between an individual and her environment). The supposed law under discussion is some sort of interpersonal law, specifying similarities across individuals. So even if simulators believed such a law, this would not make the simulation heuristic collapse into a theorizing heuristic of the sort theory-theorists en-dorse.
Part of the foregoing argument is that one cannot use a priori consider-ations to establish that simulating mindreaders must utilize a resemblance-to-self premise. But this doesn’t exclude the possibility of an empirical dis-covery that such a premise is in fact used. Indeed, we shall later encounter a bit of such empirical evidence.8The precise import of that evidence, how-ever, is debatable. Moreover, the notion that mentalizers systematically em-ploy a resemblance-to-self premise is very tenuous, because mentalizing is not always directed at similar targets. People anthropomorphize; they ascribe propositional attitudes and feelings to nonhuman objects such as animals, cartoon characters, and even moving geometrical shapes (as illustrated by the Heider and Simmel study reported in section 1.4). Do people really believe these targets to be similar to themselves?
We have just looked at one of several arguments attempting to show that ST collapses into TT. It’s time now to examine two others. Daniel Dennett (1987) was perhaps the first to advance a collapse argument against ST.
An interesting idea. . . is that when we interpret others we do so not so much by theorizing about them as by using ourselves as analog computers that produce a result. Wanting to know more about your frame of mind, I somehow put myself
in it, or as close to being in it as I can muster, and see what I thereupon think (want, do. . .). There is much that is puzzling about such an idea. How can it work without being a kind of theorizing in the end? For the state I put myself in is not belief but make-believe belief. If I make believe I am a suspension bridge and wonder what I will do when the wind blows, what ‘‘comes to me’’ in my make-believe state depends on how sophisticated my knowledge is of the physics and engineering of suspension bridges. Why should my making believe I have your beliefs be any different? In both cases, knowledge of the imitated object is needed to drive the make-believe ‘‘simulation,’’ and the knowledge must be organized into something rather like a theory. (1987: 100–101)
A response to Dennett’s collapse argument was not long in coming (Goldman, 1989). There are two ways a simulation might be successfully executed. If a computer or a person seeks to simulate a system fundamentally different from itself (e.g., a weather system or an economy), it must be driven by a good theory of that target. Let us call this theory-driven simulation. Not all simulation need be like this, however. If a simulating system resembles the target, it might succeed by engaging some of the processes or operations that it shares with the target. It won’t need a theory to do this, neither a theory of the target nor a theory of itself. This form of simulation was called process-driven simulation (Goldman, 1989). In the mindreading case, process-process-driven simulation can succeed in producing a final state that is identical or isomor-phic to that of the target as long as (1) the process or mechanism driving the simulation is identical, or relevantly similar, to the process or mechanism that drives the target and (2) the initial states of the simulating system (the at-tributor) are the same as, or relevantly similar to, those of the target. Process-driven simulation does not collapse into theorizing.
Critics may argue that this response to the collapse argument is too quick.
They will remind us that the postulated theorizing does not consist of explicit beliefs, beliefs explicitly represented in the cognitive system. Theory-theorists commonly claim that each cognitive system should be understood in terms of a tacit theory, a theory that isn’t represented in the system but that underlies the system’s operations. When the notion of a tacit theory is properly un-derstood, they contend, all interesting cognitive activity turns out to be sub-served by theorizing. Once it is appreciated that theorizing may be tacit and subpersonal, we see that any simulation process can and should be reinter-preted in terms of tacit theorizing. This is the third type of collapse argument to be discussed.
A central question, then, is: When is it appropriate to credit a system with possession of a tacit theory? Drawing on a suggestion of Gareth Evans (1981), Martin Davies (1987) proposed that a person be credited with a tacit theory (or tacit knowledge of a theory), provided that, for each separate proposi-tion in the theory, there is a corresponding separate element inside the per-son that causally mediates between premises and conclusions that the perper-son
explicitly represents. It is further required that the overall causal pattern in the structure should duplicate the logical pattern of the relations within the theory. Now consider the case of a hypothetical attributor using a simulation routine to draw a conclusion about a target’s mental state. Doesn’t the sim-ulation routine guarantee that some elements inside the attributor causally mediate between his explicit premises and conclusions, and that the causal structure of these elements mirrors the logical structure of a psychological theory (set of laws)? Jane Heal argues that, on the foregoing account of tacit theory possession, it follows that a simulating attributor uses a tacit theory (Heal, 1994: 131). Similarly, argues Heal, if I use my own heart as an instrument of simulation to make predictions about another person’s heart, it will turn out, according to this account, that I possess a tacit theory of the heart.
In revisiting this topic, Davies and Stone (2001) now concede the inade-quacy of Davies’s earlier account of tacit theory possession. They produce an example of using one gas cylinder as an instrument of simulation to make predictions about the pressure in a second gas cylinder. They show how Davies’s earlier account of tacit theory possession wrongly permits the con-clusion that the user thereby counts as having tacit knowledge of Boyle’s law.
I certainly agree with the general drift of Davies and Stone’s conclusion. An excessively permissive account of tacit theory possession must be avoided.
When it is avoided, moreover, the threat of collapse against ST itself seems to collapse. But might there not be a sufficiently stringent account of tacit knowledge that still allows the threat of collapse to go forward? Can I guar-antee that no such threat can be constructed?
I offer no definitive guarantee, but here are some guidelines that should mitigate the prospects for such a collapse. On the surface, there is a tolerably clear contrast between (mere) theory and simulation. In light of the contrast, it is prima facie implausible that evidence for a simulation routine should also and equally be evidence for a theory routine. Thus, any account of tacit knowledge that implies that the occurrence of a simulation entails the pos-session of a tacitly known theory is prima facie implausible and should be resisted.
An even more important point is that although there is a prima facie conflict between simulation and theory at the personal level, there is no conflict be-tween them at different levels. There is nothing wrong in supposing that mindreading is executed at the personal level by simulation, which is in turn implemented at the subpersonal level by an underlying theory.9Indeed, some might say, how could simulation be executed unless an algorithm for its execution is tacitly represented at some level in the brain? Isn’t such an algorithm a sort of theory?
To the last suggestion, I answer as follows. First, an algorithm isn’t a theory in the sense of a set of laws or generalizations. An algorithm is a set of (conditional)
instructions, and instructions are not laws. More specifically, an algorithm for doing and interpreting simulations is not a set of folk-psychological laws.
This point will be elaborated in the following section. Even if all operations of the mind-brain are guided at the neural level by neural algorithms or compu-tations, this does not mean that no distinctions can be drawn at higher levels of description between types of psychological activity. Even if all neural activity involves a fundamentally homogeneous set of computations, this does not imply that there is no cognitive-level distinction between factual reasoning and prac-tical reasoning (from goals to subgoals to decisions). It would be foolish to suppose that because all molecules and all cells are ultimately composed of the same fundamental particles, therefore no distinction can be drawn between different types of cells or molecules. Similarly, the fact that all thought is im-plemented by neural computations does not obliterate the cognitive-level dis-tinction between learning regularities and applying them, on the one hand, and executing simulation routines, on the other. These differences in psychologi-cal activities should not be obscured by the fact that all brain operations are computational.
Stepping back from this debate, we should take notice of two different approaches for defining ST: a negative and a positive approach. A negative approach focuses on what is denied by ST. Figure 2.3 (and 2.4) omits any belief by the attributor in a folk-psychological law. This omission is delib-erate, in that defenders of ST typically deny that such laws are used in simulation. This denial has been an important part of the traditional char-acterization of ST and comprises what I am calling the ‘‘negative approach.’’
A positive approach focuses on what ST asserts. The two critical positive features of (standard) ST are (1) the hypothesized role of pretend states and (2) the hypothesized use of mechanisms or processes of the same kind em-ployed by the target. These are clearly depicted in figure 2.3 but absent in figure 2.2. For example, the ST story shown in figure 2.3 involves the use of a decision-making mechanism, the same mechanism a target would use to make a decision. The TT story shown in figure 2.2 instead involves a factual reasoning mechanism, which no target would use in decision making.
Under the negative approach to ST, any hint that mindreading is subserved by theorizing would be a threat, because (process-driven) simulation is supposed to be free of theorizing. Under the positive approach, by contrast, a hint that mindreading is subserved by theorizing would not necessarily be a threat. Simulation could be causally responsible for mindreading even if theorizing is also at work, because theorizing might simply implement sim-ulation rather than replace it. Under the positive approach, simsim-ulation and theory are compatible. Thus, the threatened collapse need not be a collapse at all when ST receives a purely positive characterization. This is not to say that ST must endorse the presence of theorizing, even tacit theorizing, but it need not fear or resist tacit theorizing to preserve its integrity.