A Fifth Objection to Externalism

You can see the other objections here and here.

I have dubbed the following objection the epiphenomenalism objection. Although it is logically possible for the mind to be epiphenomenal (to have no effect on actual behavior) many find that conclusion to be unacceptable and to warrant discarding any theory that would lead to it. Once again we rely on the premise that externalism involves a non-causal connection between the mind and the external world (for reasons discussed earlier, as well as another reason I will present below). If the mind as described by externalism really isn’t epiphenomenal then it must be a cause of behavior, and so if we work backwards from behavior we should encounter something that can be considered the externalist mind (however an externalist chooses to define it). Immediately of course behavior is caused by the activity of neurons, which in turn are caused by the activity of other neurons. No matter how far back we follow these causes we never have evidence of a non-causal connection, only purely causal connections between neurons and other neurons, and neurons and sensory inputs. This in turn implies that either the non-causal connections that are part of externalism are not part of the mind, which really is the cause of behavior (and this is effectively a denial of externalism), or that the non-causal connections are part of the mind, but that this mind isn’t a cause of behavior (epiphenomenalism). Both these conclusions seem to imply that externalism should be dropped in favor of some other theory.

I should mention that there is also a “split-mind” possibility, namely that some of the mind is responsible for behavior, and is found by our investigation into behavior’s causes, and that there is another part of the mind that the non-causal connections are part of, but that it is not connected to the part of the mind that controls behavior. I reject this possibility because it still leads to the conclusion that the mind is at least partly epiphenomenal, and more strangely that it is composed of two completely separate parts that don’t affect each other (this is not the same as the right-left hemisphere division because the two hemispheres do communicate, through both the corpus callosum and the hindbrain).

At this point you may again be considering the possibility that connection between the mind and the external world in externalism is causal. Although I already presented an argument against that possibility allow me to give another here. Let us then consider a causal version of externalism a real possibility. We then say that the mind is connected to an object, say X, by X’s causal influence on the mind. Let’s examine then what this connection means at a given instant of time. Certainly when we look back to the moment of time where whatever information about X that influenced that mind was generated it might seem reasonable to say that our future thought about X is dependant on that X in the past and the mind in the past. However as we consider moments in time closer to the actual thought X falls out of the picture, and instead what we consider to be connected to us is the medium by which the information about X was transmitted (say the reflected light). When we reach the moment of the actual thought there is nothing left from X that we can consider to have a causal effect on us, because the effect of X on us happened some time in the past. When considering that moment of time, the moment when the thought happens, all we can say is that we have a thought about X, even though the thought isn’t connected to X. For all intents and purposes this is the same as internalism.

Two (More) Problems With Externalism

In this post I will address two problems faced by an externalist theory of the mind. Feel free to read them in whatever order you please. In these objections I make the assumption that externalism is simply a way of approaching the philosophy of the mind, not a theory that makes predictions about what is physically out there (this is actually a view that is held by some externalists). If you think that externalism can have real, observable, consequences see this objection instead.

1: The Problem Of Other Minds

The problem of other minds is a classic part of philosophy. The question is as follows: how can I be sure that other people are conscious in the same way I am? (And also how can I be sure that things such as rocks aren’t?) I think that any theory about the mind that can’t solve the problem of other minds is lacking something important, and should be rejected, since it certainly seems as if we can be sure who has a mind and who doesn’t. For example dualism and idealism are famously unable to satisfactorily solve the problem of other minds, which I personally think is a good reason to discard them. Externalism can’t solve the problem of other minds either (and internalism can). This follows from the following argument: The only things we can observe about other people are physical or that which can have a causal effect on the world. We can observe their behavior directly and we can make guesses about the activity inside their skull, but that is about it. Externalism asserts that there is a non-causal connection between thoughts (part of the mind) and the external world. It is a consequence of externalism that for a mind to be a mind (and have thoughts) it must possess this non-casual connection. Why? Well if it wasn’t required then such a connection wouldn’t be an essential part of the mind, and thus we wouldn’t consider externalism to be a good theory about the mind. (For example even though the statement that “some minds believe externalism” is true it isn’t a good theory about minds because it doesn’t tell us anything about what is essential to minds in general.) However we can never be sure when such non-causal connections are present (since as mentioned above we assumed that externalism didn’t have observable consequences), and thus we can never know with any degree of certainty if other people have minds like ours, since we have no evidence either for or against their possessing the necessary non-causal external connections.

2: The Problem Of Theory Strength

Given the kind of externalism we are discussing here, the best we can say about externalism is that it is true in the sense that it is consistent. Internalism however does make claims about the contents of the world, as well as make testable predictions, and thus the truth of internalism is a matter of certainty (not that I am saying that we are currently certain about internalism, just that we could be, given the categories of knowledge discussed in the linked post). For example internalism predicts that activity in the brain will be closely correlated with what people are thinking about, and indeed experiments have shown this to be true (or at least highly probable, since you can never eliminate all experimental error). Internalism is also incompatible with externalism, and given this we should accept internalism, and reject externalism, because of the general principle that we should accept truths that could be certain over those that are only consistent. Why should certain truths trump consistent truths? Well consider the following situation: the theory that everything is made up of the four elements can be considered a consistent truth, if we are allowed to define the four elements as we please (for example air might be subatomic particles a, b, c; earth might be … ect). However the atomic theory (everything is made of atoms) is part of the realm of certain truth, since it makes definite predictions about what we will find, its truth isn’t guaranteed by definition, it must be confirmed by experiment. We settle such cases using the principle I invoked earlier, not because it is necessarily wrong to accept the elemental theory given the right definitions, but because we seek greater predictive power and hence the atomic theory is more useful to us in our search for the truth. I argue that the internalism / externalism divide is much like this. Externalism doesn’t explain anything that internalism doesn’t, it is simply a more convenient way to talk about certain situations. Internalism on the other hand does make predictions about what we should find in our physical investigations into consciousness, and thus is of greater use in our search for the truth about the mind and consciousness.

A Kind of Externalism

Although I can’t see any reason to believe that our thoughts extend beyond our minds, or require an external world to have content or exist, it is an undeniable fact that some things are external to us. Obviously physical objects and events are one such thing. More interesting however is that the truth of statements is also external to us.

For example the truth of the statement “the sun is the center of the solar system” is independent of what people think its truth is. This is to say the truth of the statement depends only on the nature of the sun and the solar system, and not on human thoughts. (Of course an obvious exception to this rule is any statement that refers directly to human thoughts.) Another point to bring up is that I take it as a given that the statement is well defined (that each of its words has a well understood meaning). This is not to say that the truth of a statement is dependant on the meaning of words, simply that because words are one of the few methods we have for communication a failure to understand what the words mean will result in a failure to understand the statement. Relativists of course argue that because people understand the meaning of words in different ways there is really no truth that is independent of the individual, but I say that in a case where people understand the same word in different ways they are really just considering different statements, and the truth of the statements they each consider is external to them.

Unfortunately this limited version of externalism can lead some people to believe that externalism is true with respect to thoughts as well. This happens for two reasons. One possibility is that people accept Frege’s definition of meaning, namely that meaning is defined by how a word contributes to the truth of statements. Accepting this they then assume that since meaning is directly connected to the external world, and because meaning is a key component of thought, then thought must also be directly connected to the external world. The mistake being made here is a failure to distinguish between two kinds of meaning, the objective meaning and the personal meaning of a word. Although the objective meaning does depend on the external world the personal meaning may or may not, and thus it is bad reasoning to assume that because the objective meaning depends directly on the external world that the personal meaning, the kind of meaning that is a component of thought, must do so as well.

The second mistake people are sometimes led to make is to assume that because our thoughts often take the form of statements that thoughts must, like statements, depend on the external world. The mistake being made here is that it is not the statement that depends on the external world, but the truth of the statement. I accept that the truth of certain thoughts might also be said to depend on the truth of the external world, but since there is no indication that our minds have direct access to external truth of thoughts (except through perception) there is no reason to say that our thoughts are dependant on their objective truth or falsehood. (This of course also explains how we can be in error and not know it, as there would be something strange in saying that our thoughts are dependant on external truth and yet that we are unable to use that connection to our advantage.)

Of course just because our thoughts aren’t dependant on the objective truth doesn’t mean we can’t have access to such truth. A trivial case of course is our ability to know the truth or falsehood of statements that are tautologies or contradictions. However most interesting statements are neither true nor false necessarily. We discover the truth of such statements through perception and experience. We judge that probability of a statement is greater given our perception of certain evidence (even if this “evidence” involves direct perception of the contents of the statement, since there is a small possibility that our perceptions could be mistaken). It is true that given a single perception we are unlikely to be absolutely sure that the statement is true or false, but given repeated observations the probability of the statement being true generally approaches one or zero. (Because if Pr(s | m) != Pr(s) & Pr(s | n) != Pr(s) then Pr(s | m & n) != Pr(s | m)) Of course no matter how many observations you make nothing can be absolutely certain, but we can be certain enough for all practical purposes, enough to say that we know the truth of various statements.