4.9 Intentionality of the mental

The existence of a stone, by contrast, does not by that fact alone refer to something apart from that stone. All mental states and speech acts seem to be intentional. They are like signs, gestures and sentences that indicate or represent the things they are about. In a famous declaration of Brentano (1874), “intentionality is the mark of the mental”.

When philosophers examined dispositions, many were fascinated by the fact that even physical dispositions seem to be dispositions for something else, namely for their effects, and thus by their nature were capable of indicating something apart from themselves.^4.16Place (1996) hypothesized that there was something fundamentally intentional about all dispositions: that “intentionality is the mark of the dispositional”. If this were so, we might be seeing some primitive kind of intentionality in physics. This ‘physical intentionality’ could emerge perhaps in larger systems as the fully-fledged intentionality that we attribute to the mental, by a kind of panpsychist hypothesis.

There has been debate, starting with Mumford (1999), on whether this idea of physical intentionality is useful or even correct. Most recently, Bird (2007, §5.7) offered a series of arguments for a permanent distinction between physical dispositions and mental intentionality. He argues that direction of causality is different in the two cases. Taking sensation as an example, he points out that sensations are caused by what they refer to whereas physical dispositions are the opposite: they cause the effect that they may be said to ‘refer’ to. Bird also notes that, with mental intentionality of sensations and ideas, the object of reference may be inexistent, may be indeterminate, and may be referred to only extrinsically. The linguistic context of mental reference in a person’s mind is logically intensional, by which is meant the referenced object cannot be replaced by something to which it is in fact identical, since the person may not be aware of that. With the exception of possible inexistence, none of these characteristics applies in the case of physical dispositions. Bird concludes that mental intentionality is not a relation between between a thought and an object. It is more akin to a mode of representation which is quite unlike causation.

I agree with Bird that mental and physical intentionalities are not the same, and I will go back to Brentano’s emphasis on the distinct nature of mental and physical being. I do not want to reduce physical causation to mental intentionality or even explain (somehow nonreductively) the mental intentionality in terms of the physical, as then (I find) whatever is reduced no longer has its original character but is replaced by some poor shadow of its previous nature. Bird (2007)’s reasons are essentially structural, whereas I hold that the arguments from content are sufficiently strong to maintain the difference between mental and physical dispositions. They may both be dispositions, but they are not intentional in the same way.

Not all of Bird’s structural arguments will be followed in this book. The reason is that, as even he realizes, the argument about different directions of causality does not hold for the intentionality of desires, emotional and motivational dispositions, etc. Desires do cause what they refer to intentionally, rather than the opposite as for thoughts and sensations. In Chapter 25 I will present a theory of how thoughts and sensations can be generated on the basis of desires and dispositions. In that case, not even sensations and thoughts have reversed causality compared with physical dispositions. The result is that mental and physical dispositions are more similar causally, although their contents are completely different.

As a reminder of this difference, I will list those capabilities of mental processes that are unavailable to physical processes. Apart from the intentionality already described, there are the remaining items on Bird’s list, namely that minds can think of an object that may be inexistent, may be indeterminate, or may be referred to only extrinsically. Lund (2009) lists the further facts that mentality can think of truth or falsity and may think with vagueness or ambiguity or with logic and argument. Logical principles, meanings, abstractions, and moral principles are all capable of being only in minds and not in physical systems. Our challenge is to relate such minds to our natural world of physical dispositions.