Introduction:

C.D. Broad, in his chapter “The Traditional Problem of Body and Mind,” tackles the “interaction” of the mind and body in certain complex organisms (such as humans). Specifically, he takes up the challenges and issues surrounding two questions: (1) whether the mind “acts” upon the body; and (2) whether the body “acts” upon the mind.

Definitions: “Animate” and “Two-Sided Interaction”

Before we get into any detail, it is necessary to make sure our definitions are clear. First, Broad uses the term “animate” to describe the close connection between the mind and body. However, he does not wish to imply any particular theory of the mind by using this term. Rather, it is merely a “neutral name to express the fact that a certain mind is connected in some peculiarly intimate way with a certain body, and, under normal conditions, no other body” (243).

Another important term used by Broad is “Two-Sided Interaction,” a name he uses to convey the common-sense view of the interaction between mind & body. Under this view, two things are true: the mind acts upon the body and the body acts upon the mind. It is a two-way interaction (hence, the name). So, if someone stabs me in the back with a knife, thus damaging my body, my body will “act” upon the mind, causing “a painful sensation” to arise there. Conversely, if I hold a knife in my hand and desire to thrust it into the back of a poor, unsuspecting insurance salesman, my mind acts upon my body whenever that desire is followed by the appropriate movement in my arm.

*Causation and “Concomitant Variation”

Naturally, since we are talking about the mind and body acting upon one another, the mind/body problem must handle certain problems about causation. At this point, Broad states that causation cannot simply mean “concomitant variation,” or the idea that an event or variation in one sphere (mind or body) is accompanied by a corresponding event or variation in the other, but that it is wrong to think that “causation” is anything over and above this. The reason for this is quite simple: if causation were simply concomitant variation, the question would fall: the mind/body problem would be no more. What we are after when we ask the question “does the mind act upon the body” is not whether there are merely concomitant events and variations in both the mind & body. We know that there are—we experience it all of the time. What we wish to know is whether there is any direct causal relation between the mind and body and an answer to this question requires more than concomitant variation: “some other relation between a pair of events” is required (245).

Humean Skepticism: One-sided

One-Sided Interaction: A Plausible View

Broad thinks that denying that the body acts on the mind as consequences far more implausible than accepting it. If a man were to deny this fact, he would immediately face the trouble of specifying the “cause” of new sensations. Suppose I’m in the wilderness around Sandy, Oregon, trying to apprehend a Vietnam veteran in the woods who has just escaped from our jail. While I am searching the forest for him, I am suddenly stabbed in the back by a clever trap set up by our Rambo. A new sensation suddenly comes to my mind (and not a pleasant one at that). If I reject the notion that an event in the body (namely, the penetration of my skin by a stick that Rambo cleverly whittled to become like a spear) caused the sensation of pain I am experiencing, then I have to look to other mental events for the cause. Thus, I am left either supposing it is an uncaused event, that it is caused by other mental events that “I cannot discover by introspection or retrospection,” or that it has been caused “telepathically by other finite minds or by God” (251). Broad considers all three of these options to be radically ridiculous, leaving us to take up the common-sense view that Rambo’s whittled stick, and the fact that it has become lodged in my back, is what has caused the sensation.

Interestingly, while Broad argues that denying that the body acts on the mind is implausible, it is not so ridiculous to deny that the mind acts on the body. The reason appears to be that this second denial, quite unlike the first, does not involve postulating “unfamiliar entities and modes of action” (252). A person who denies that the mind acts on the body is left with two (perhaps) plausible outs. First, he could argue that “human bodies are extraordinarily complex physical objects” and that it is simply unfair to set limits as to what they could do unaided by minds (252). As Broad argues, it may be hard to imagine our bodies without our minds, engaging in complex activities, but it is not as implausible as postulating ad hoc entities and modes of action.

Second, one could argue that all causation is physical causation and that certain physical events (such as events in the brain) are always attended (or accompanied) by a complex mental-state. Thus, it is true that certain mental states will always precede certain physical actions, but the mental-state plays no causal role in bringing about that physical action. Rather, the physical action is caused by another physical state (a brain-state) and that physical state is always attended by (or causes) the mental-state. While Broad does not believe that this view is the correct view, he finds it a plausible position and does not find it nearly as absurd as the view that the body does not act on the mind.

-- DanielS - 14 Nov 2005