Motus Mentis

One of the knottier topics in philosophy of mind is intentionality. The term refers to the way our thoughts are about their objects, and intentionality is often considered to be an exclusive hallmark of the mental. A thought can be “about” Paris, but a stone, or a lampshade, cannot be.

Well then, what about something like a map of Paris, or a book about Paris? The response usually given is that a book about Paris derives its “aboutness” from the minds of the person who wrote it and the person who reads it. In other words, only minds have intrinsic intentionality, and only minds can then bestow a second-order, derived intentionality on the artifacts they create.

So one of the problems (one of many!) for the philosopher who wants to develop a naturalistic account of mind is to root our “intrinsic” intentionality, somehow, in the material world. Some would have it, though, that the mental is irreducibly distinct from the physical, and that intentionality is a property of mind alone. This difficulty in seeing how any collection of matter, regardless of the complexity of its organization, can have this sort of “aboutness” is, to some, a fatal flaw in materialism.

I think, however, that a bridge can be built, if we are willing to accept the power of natural selection to create design. It seems to me that many highly intelligent people, despite having a fairly accurate intellectual overview of evolutionary theory, are still reluctant to embrace fully its most important implication, which is that sophisticated and purposeful design can enter the world without there being a mind to act as the designer. This “bootstrapping” is of course completely at odds with our ordinary experience, and is so deeply counterintuitive that I think even some very sophisticated thinkers stumble over it.

How can there be ‘purposeful’ design without a designer whose purpose it is? The answer is that the design accrues, quite naturally, to the reproductive benefit of material entities that are organized in such a way as to be able to make copies of themselves. The design elements that contribute to reproduction proliferate, and further improvements are gradually built upon them, simply because they are there for the next round. In this way, design emerges from a natural process that is itself quite mindless. The remarkable part is not the seemingly magical emergence of purposefulness, it’s the emergence of self-replicating arrangements of matter in the first place. Once that is in place, the “aboutness”, I am arguing, follows on quite naturally.

Before there were self-replicating organisms, there truly was no intentionality in the world. There were relationships between objects – for example, a river might have scooped a depression in its rocky bank – but such relationships are symmetrical, and intentionality of the sort we are seeking to account for is not. Bill Vallicella, the Maverick Philosopher, makes that point in this post. The rock is shaped by the river, but the river’s path is also confined by the rock. A lock and a key are symmetrically “about” each other. But when I think of Paris, there is no sense in which Paris is thinking about me. Intentionality is an asymmetrical relationship.

As soon as replicators arrived on the scene, however, a new game was in play. As these early entities reproduced, the natural variations among their offspring were tested against the environment, and those new structures or behaviors that increased the organism’s likelihood of generating offspring tended to increase in the population.

Now we can begin to take a new perspective in interpreting such an organism’s form and behavior. Because the types that fail to replicate simply vanish, while others become numerous, we can begin to ask what the salient differences are, and we can begin to assess the forms and behaviors of such replicators in terms of how they contribute to the organism’s chances of reproduction. In other words, why did type A die off, while type B proliferated? The difference will be explicable in terms of which features made it more likely that the organism acquired food, was not itself eaten, produced viable offspring, and so forth. In other words, even though the replicator itself (we are still speaking here of very simple organisms) has no idea whatsoever of any “aims” or “purposes”, a goal-oriented paradigm is still a useful explanatory stance for us to take when evaluating its form and behavior. This is what Daniel Dennett calls “the intentional stance”.

On the purely somatic level, consider the relationship between the morphology of an animal – say the beak of a finch – and its food. In the GalÁ¡pagos Darwin observed a radiation of finch species among the several islands, and saw that each finch wore a beak that was adapted to the particular flora (and their seeds) of its local habitat. It is perfectly reasonable to view a particular beak as being “for”, or “about”, a particular food source, though the bird itself, we may assume, makes no inner representation of such purposefulness.

With due respect to Dr. Vallicella et al., I maintain that there is no reason not to say that the legs of an animal are “for” running, that its heart is “for” pumping blood, etc. Some will object that such a description implies a designer with a purpose in mind, but I believe that this is an unwarranted generalization from our ordinary human experience. There was a designer, yes, but no mind. A horse’s leg, designed by natural selection, is no less “for” running (an ability that benefits a horse’s reproductive fitness) than a hammer designed by a human is “for” driving nails.

Consider a frog, exquisitely designed for snatching flying insects from the air. This behavior is triggered visually; the passage of a fly across the frog’s visual field sets in motion a cascade of neural events that ends with the fly being zapped (this is already a hugely complex operation, and the end product of a tremendous amount of evolutionary R&D). This does not mean that the frog builds a little mental replica of the fly, or that it has any conscious perception whatsoever, for that matter. But it does mean that there are neurological patterns and structures in the frog that are “about” getting food, and that can distinguish something that is worth zapping from something that isn’t.

Next, consider an animal that differentiates between similar prey, for example a bird that shuns a brightly colored frog in favor of a drab one that happens not to be poisonous. Or a snake that predicts the course of its prey as it runs behind a boulder. In each case there are complex cognitive structures at work, recognizing prey as prey, making decisions about whether it is suitable, and if so, how to catch it. This is purposeful, intentional behavior.

In this way we can see that organisms of increasing neural complexity will exhibit more and more behavior, presumably driven by transitions between neurological states, that is chock-full of “aboutness”, of intentionality that is as “intrinsic” as it gets. Finally, after a great deal of design work, we get to animals like ourselves, with brains that can learn from their mistakes, that can use language, that can grieve, that can think of Paris.

Now all of this intentionality- this abundance of aboutness – is, it seems to me, completely independent of consciousness. The human brain has the additional ability, perhaps unique, to point the aboutness inward, to have thoughts about our thoughts, and this is indeed a great leap forward in cognitive design. And in doing this – in taking the intentional stance toward our own thoughts, from the unique viewpoint of introspection – we cannot see their physical underpinning, and so we think of them as “intrinsically” intentional. But this introspection is only the topmost story in a preexisting tower of intentionality that was built from the ground up by natural selection, and it is an error to mistake what it perceives for the whole show. Yes, a human artifact such as a book “derives” its intentionality from our own. But there is a special class of things in the world – living organisms – that get theirs from Nature.

Finally, there is one last pill to swallow in order to “see how deep the rabbit-hole goes”. Because our brains are, at bottom, physical systems, driven from one state to the next by physical causality, their semantic reliablity – which is apparently quite high when we do things like mathematics or philosophy – is due entirely to the syntactic tuning that has been done over our long and harsh evolutionary history. As Dennett puts it:

The appreciation of meanings – their discrimination and delectation – is central to our vision of consciousness, but this conviction that I, on the inside, deal directly with meanings turns out to be something rather like a benign ‘user-illusion’.
-Brainchildren

This is a rather unsettling conclusion, as it undermines our certainty about the reliablity of our reason. But if you read the newspapers, after all, that should come as no surprise.