Contrastive mental causation

Any theory of mind needs to explain mental causation. Kim’s (upward) exclusion argument concludes that non-reductive physicalism cannot meet this challenge. One classic reply is that mental properties capture the causally relevant level of generality, because they are insensitive to physical realization. However, this reply suggests downward exclusion (if mental properties are causally efficacious, their physical realizers are causally impotent), contrary to physicalism’s assumption of closure. This paper shows how non-reductive physicalists can solve this problem by introducing a contrastive account of causation with non-exhaustive contrasts. That view has independent justification, because it is also needed to solve other puzzles. On this theory, both a mental property and its physical realizer can cause the same physical effect without lapsing into any problematic overdetermination when they cause that effect in contrast with distinct foils. This contrastive solution has advantages over previous accounts of mental causation and is defended against objections.

     

A recruitment theory of force-time relations in the production of brief force pulses: the parallel force unit model

A theory, the parallel force unit model, is advanced in which the buildup and decline of force in rapid responses of short duration are assumed to reflect variability in timing of several parallel force units. Response force is conceived of as being a summation of a large number of force units, each acting independently of one another. Force is controlled by either the number of recruited force units or the duration each unit contributes its force. Several predictions are derived on the basis of this theory and are shown to be in qualitative agreement with empirical findings about both the mean and variability of brief force impulses. The model also has consequences for the temporal properties of a response. For example, under certain circumstances, it predicts a reciprocal relation between reaction time and response force. Although the theory is proposed as a psychological account, relations between the assumptions and basic principles in neurophysiology are considered. Possible future applications and generalizations of the theory are discussed.     

Representing causation

The dynamics model, which is based on L. Talmy's (1988) theory of force dynamics, characterizes causation as a pattern of forces and a position vector. In contrast to counterfactual and probabilistic models, the dynamics model naturally distinguishes between different cause-related concepts and explains the induction of causal relationships from single observations. Support for the model is provided in experiments in which participants categorized 3-D animations of realistically rendered objects with trajectories that were wholly determined by the force vectors entered into a physics simulator. Experiments 1-3 showed that causal judgments are based on several forces, not just one. Experiment 4 demonstrated that people compute the resultant of forces using a qualitative decision rule. Experiments 5 and 6 showed that a dynamics approach extends to the representation of social causation. Implications for the relationship between causation and time are discussed.     

Causal Exclusion and Dependent Overdetermination

Jaegwon Kim argues that unreduced mental causes are excluded from efficacy because physical causes are sufficient in themselves. One response to this causal exclusion argument is to embrace some form of overdetermination. In this paper I consider two forms of overdetermination. Independent overdetermination suggests that two individually sufficient causes bring about one effect. This model fails because the sufficiency of one cause renders the other cause unnecessary. Dependent overdetermination suggests that a physical cause is necessary and sufficient for a given effect, but it necessitates a mental cause of the effect as well. This model fails because the necessity of the mental cause renders the physical cause individually insufficient.     

The Inherent Empirical Underdetermination of Mental Causation

It has become a popular view among non-reductive physicalists that it is possible to devise empirical tests generating evidence for the causal efficacy of the mental, whereby the exclusion worries that have haunted the position of non-reductive physicalism for decades can be dissolved once and for all. This paper aims to show that these evidentialist hopes are vain. I argue that, if the mental is taken to supervene non-reductively on the physical, there cannot exist empirical evidence for its causal efficacy. While causal structures without non-reductive supervenience relations can be conclusively identified in ideal discovery circumstances, it is impossible, in principle, to generate evidence that would favour models with mental causation over models without. Ascribing causal efficacy to the mental, for the non-reductive physicalist, is a modelling choice that must be made on the basis of metaphysical background theories or pragmatic maxims guiding the selection among empirically indistinguishable models.     

Can determinable properties earn their keep?

Sydney Shoemaker’s ‘Subset Account’ offers a new take on determinable properties and the realization relation as well as a defense of non-reductive physicalism from the problem of mental causation. At the heart of this account are the claims that (1) mental properties are determinable properties and (2) the causal powers that individuate a determinable property are a proper subset of the causal powers that individuate the determinates of that property. The second claim, however, has led to the accusation that the effects caused by the instantiation of a determinable property will also be caused by the instantiation of the determinates of that property—so instead of solving the problem of mental causation, the Subset Account ends up guaranteeing that the effects of mental properties (and all other types of determinable property) will be causally overdetermined! In this paper, I explore this objection. I argue that both sides in this debate have failed to engage the question at the heart of the objection: Given that both a determinable property and its determinates have the power to cause some effect (E), does it follow that both will actually cause E when the relevant conditions obtain? To make genuine progress towards answering this question, we need to take a serious look at the metaphysics of causation. With the debate properly reframed and issues about the metaphysics of causation front and center, I explore the question of whether the Subset Account is doomed to result in problematic causal overdetermination.     

Making It Totally Explicit

Abstract

This paper begins by isolating the reductive component of Brandom's inferentialism. In order to assess to what extent that reductive component is supported by the considerations Brandom marshals in its defense, I assess the comparative degree of support those considerations provide a non-reductive counterpart of Brandom's original, reductive theory. One of the central claims here is that once the reductive and non-reductive theories are placed side-by-side, it is clear that, save one, all of the considerations Brandom marshals in defense of inferentialism equally well support its non-reductive counterpart. This shows that those considerations offer no support for the reductions at inferentialism's heart.

What the considerations raised here ultimately show is that Brandom's defense of the reductive core of his theory ultimately rests on the simple fact that it has a certain feature, namely, that it is reductive in the sense reserved here. I close with a brief discussion of some advantages that some reductive theories have over non-reductive ones, but show how none of these advantages are had by Brandom's theory in particular.     

The stability of precision grip force in older adults

The exceedingly large grip forces that many older adults employ when lifting objects with a precision pinch grip (Cole, 1991) may compensate for a reduced capability to produce a stable isometric force. That is, their grip force may fluctuate enough from moment to moment to yield grip forces that approach the force at which the object would slip from grasp. We examined the within-trial variability of isometric force in old (68-85 years, n = 13) and young (n = 11) human subjects (a) when they were asked to produce a constant pinch force at three target levels (0.49, 2.25, and 10.5 N) with external support of the arm, hand, and force transducer and (b) when they were asked to grasp, lift, and hold a small test object with a precision grip. Pinch force produced in the first task was equally stable across the two subject groups during analysis intervals that lasted 4 s. The elderly subjects produced grip forces when lifting objects that averaged twice as much as those produced by the young subjects. The force variability during the static (hold) phase of the lift for the old subjects was comparable with that used by the young subjects, after adjusting for the difference in grip force. The failure to observe less stable grip force in older adults contradicts a similar recent study. Differences in task (isometric grip force versus isometric abduction torque of a single digit) may account for this conflict, however. Thumb and finger forces for grip are produced through coactivation of many muscles and thus promote smooth force output through temporal summation of twitches. We conclude that peripheral reorganization of muscle in older adults does not yield increased instability of precision grip force and therefore does not contribute directly to increased grip forces in this population. However, force instability may affect other grip configurations (e.g., lateral pinch) or manipulation involving digit abduction or adduction forces.     

Physicalism and sparse ontology

A major stumbling block for non-reductive physicalism is Kim’s disjunctive property objection. In this paper I bring certain issues in sparse ontology to bear on the objection, in particular the theses of priority monism and priority pluralism. Priority pluralism (or something close to it, anyway) is a common ontological background assumption, so in the first part of the paper I consider whether the disjunctive property objection applies with equal force to non-reductive physicalism on the assumption that priority monism is instead true. I ultimately conclude that non-reductive physicalism still faces a comparable problem. In the second part, I argue, surprisingly enough, that what I call ‘fine-grained reductionism’, a particular version of which Kim proposes as an alternative to non-reductive physicalism, may work better in the monist framework than the pluralist one. I conclude that issues in sparse ontology, therefore, are more relevant to the debate about physicalism than one may have thought.

Overdetermination and Elimination

Abstract

I focus on two arguments, due to Jaegwon Kim and Trenton Merricks, that move from claims about the sufficiency of one class of causes to the reduction or elimination of another class of entity, via claims about overdetermination. I argue that in order to validate their move from sufficiency to reduction or elimination, both Kim and Merricks must assume that there can be no ‘weak overdetermination’; i.e., that no single effect can have numerically distinct but dependently sufficient causes occurring at the same time. One problem for both arguments is that weak overdetermination isn't obviously objectionable. That point has been well made before. But I want here to go further than merely shifting the burden of proof onto the advocates of overdetermination arguments. I want to tease out why they are so convinced that we must resist weak overdetermination and explain why their conviction is misguided. Both Merricks and Kim, I shall argue, ultimately rest their case on the same motivating principle, which I call the principle of additional causal powers. This principle, I argue further, should be rejected. It lacks argumentative support, and it begs the question against those at whom the arguments are directed.     

Causal Overdetermination and Modal Compatibilism

Compatibilists respond to the problem of causal exclusion for nonreductive physicalism by rejecting the exclusionist’s ban on overdetermination. By the compatibilist’s lights there are two forms of overdetermination, one that’s problematic and another that is entirely benign. Furthermore, multiple causation by “tightly related” causes requires only the benign form of overdetermination. Call this the tight relation strategy for avoiding problematic forms of overdetermination. To justify the tight relation strategy, modal compatibilists appeal to a widely accepted counterfactual test. The argument of this paper is that the counterfactual test fails to legitimize the tight relation strategy as it fails to adequately distinguish between problematic and benign overdetermination. Contrary to modal compatibilists, modal dependence does not suffice for benignity. I conclude by arguing that adequately addressing overdetermination worries requires a much heavier metaphysical burden than modal compatibilists have typically recognized.     

Causal Exclusion and Causal Autonomism

The causal exclusion problem is often considered as one of the major difficulties for which non-reductive physicalists have no easy solution to offer. Some non-reductive physicalists address this problem by arguing that mental properties are to some extent causally autonomous. If this is the case, then mental properties will not be causally excluded by their physical realizers because causation, in general, is a relation between properties of the same level. In this paper, I argue that the response from causal autonomy cannot be successful for two reasons. First, it does not offer a satisfactory explanation for how mental particulars can have causal efficacy in a non-reductive physicalist framework. Second, the causal considerations underpinning this response do not really support the conclusion that mental properties are causally autonomous.     

A Nonreductivist Solution to Mental Causation

Nonreductive physicalism provides an appealing solution to the nature of mental properties. But its success as a theory of mental properties has been called into doubt by claims that it cannot adequately handle the problems of mental causation, as it leads either to epiphenomenalism or to thoroughgoing overdetermination. I argue that these apparent problems for the nonreductivist are based in fundamental confusion about causation and explanation. I distinguish two different types of explanation and two different relations to which they appeal: causation and determination. I argue that these types of explanation do not compete with one another, nor do these relations jointly result in overdetermination. In closing I develop a nonreductivist solution to mental causation which avoids both the hazards of epiphenomenalism and of overdetermination and so demonstrates a way to save nonreductive physicalism from the problems of mental causation.     

Three Varieties of Causal Overdetermination

Causal overdetermination worries arise in a number of domains, but most notably in the philosophy of mind. In discussions of such worries, alleged examples of causal overdetermination are uniformly viewed as prima facie problematic. While all alleged cases of overdetermination might (or might not) be problematic, I aim to show that they are so for different reasons. Examples of causal overdetermination neatly divide into three varieties, corresponding to the connections between the mechanisms and the properties of the causes. Future debates over overdetermination, and mental causation in particular, should pay heed to this distinction.     

Functionalism and Causal Exclusion

Abstract: Recent work by Jaegwon Kim and others suggest that functionalism leaves mental properties causally inefficacious in some sense. I examine three lines of argument for this conclusion. The first appeals to Occam's Razor; the second appeals to a ban on overdetermination; and the third charges that the kind of response I favor to these arguments forces me to give up "the homogeneity of mental and physical causation". I show how each argument fails. While I concede that a positive theory of mental causation is desirable, there is no reason to think that functionalism renders such a theory unattainable.     

Causal Overdetermination and Kim’s Exclusion Argument

Jaegwon Kim’s influential exclusion argument attempts to demonstrate the inconsistency of nonreductive materialism in the philosophy of mind. Kim’s argument begins by showing that the three main theses of nonreductive materialism, plus two additional considerations, lead to a specific and (by now) familiar picture of mental causation. The exclusion argument can succeed only if, as Kim claims, this picture is not one of genuine causal overdetermination. Accordingly, one can resist Kim’s conclusion by denying this claim, maintaining instead that the effects of the mental are always causally overdetermined. I call this strategy the ‘overdetermination challenge’. One of the main aims of this paper is to show that the overdetermination challenge is the most appropriate response to Kim’s exclusion argument, at least in its latest form. I argue that Kim fails to adequately respond to the overdetermination challenge, thus failing to prevent his opponents from reasonably maintaining that the effects of the mental are always causally overdetermined. Interestingly, this discussion reveals a curious dialectical feature of Kim’s latest response to the overdetermination challenge: if it succeeds, then a new, simpler and more compact version of the exclusion argument is available. While I argue against the consequent of this conditional, thereby also rejecting the antecedent, this dialectical feature should be of interest to philosophers on either side of this debate.     

SUBSET REALIZATION,PARTHOOD, AND CAUSAL OVERDETERMINATION

Defenders of the subset view of realization have claimed that we can resolve well‐known worries about mental‐physical causal overdetermination by holding that mental properties are subset realized by physical properties, that instances of subset realized properties are parts of physical realizers, and that part‐whole overdetermination is unproblematic. I challenge the claim that the overdetermination generated by the subset view can be legitimated by appealing to more mundane part‐whole overdetermination. I conclude that the subset view does not provide a unique solution to overdetermination worries.     

Evaluation of key points in the sit-to-stand movement using two force platforms

Three key points of the sit-to-stand (STS) movement were confirmed as aspects of the ground reaction force (GRF): the onset, maximum GRF, and seat-off. 46 healthy subjects (M age = 22.2 yr., SD = 4.4) participated. During the STS movement, two vertical force platforms were used to measure the resultant GRF, defined as the whole-body force, and its two components, the buttock and leg GRFs. The onsets of the component GRFs identified the sequence of the important time points in the STS movement more precisely than the onset of the resultant GRF. Data showed that the maximum whole-body GRF, the maximum GRF of both legs, and seat-off appeared in sequence and not simultaneously.     

Changes in pinch force with bidirectional load forces

The forces used to grasp an object were measured while positive (push) and negative (pull) load forces were applied to the hand under varying frictional conditions. Subjects held between the tips of their thumb and index finger a manipulandum composed of two symmetrically mounted disks. The manipulandum was connected to the stage of an electromagnetic linear motor that generated load forces under computer control. In the first experiment, subjects held the position of the manipulandum constant while the motor generated forces in first the positive and then the negative direction. The motor force at which the manipulandum slipped from the fingers was measured in the second experiment. In both experiments, friction was varied by changing the surface (sandpaper, suede, or plastic) of the manipulandum disks. The pinch forces produced by subjects were linearly related to changes in motor force in both the positive and negative directions, with the slope of this relation varying as a function of the surface properties of the manipulandum. The modulation of pinch force with motor force was influenced, however, by the direction of the load force; higher forces were produced in response to negative load forces. Slip forces varied as a function of pinch force and surface texture; higher forces were associated with materials with lower coefficients of friction. These findings suggest that the friction between the skin and an object being grasped changes as a function of the direction of force that the object applies to the skin, possibly due to the anisotropic nature of glabrous skin, and that this mechanical property contributes to variations in pinch force.