Monday, March 28, 2005

The Primary Qualities

I have been reading DM Armstrong’s book “Perception and the Physical World’, in which he proffers a defence of direct realism, based on a definition of perception as the acquiring of knowledge, or the inclination to believe, particular facts about the physical world by means of the senses. On the whole I found his thesis unconvincing, due to the insufficient attention paid to the phenomenal feel of sensations and to neurophysiology (which is understandable considering the book was written more than 40 years ago).

However, there is one argument in his book concerning the primary qualities which I aim to explore and develop further in this post. Armstrong presents an argument, based on the ideas of Berkeley and Hume, that it is logically impossible for a physical object to have nothing but the primary qualities.

Historically, primary qualities have been described as the ‘real’ properties of matter which exist independently of the human mind, such as shape, size, position, duration, divisibility, movability and impenetrability. Secondary qualities are those that supposedly do not inhere in the physical object but are dependent on the observing mind and the sensory organs, such as colours, smells, tastes, heat and cold.

The argument Armstrong puts forth is that the primary qualities by themselves do nothing to distinguish a physical object from empty space. For example, shape, size, duration and position are all things which could be ascribed to regions of empty space.

With regard to motion, a body is in motion if it is in a series of adjoining places at successive times. This means that motion can be analysed in terms of concepts of shape, size, position and duration but that it is not a new primitive concept which can serve to differentiate physical objects from empty space.

Similarly, divisibility refers to the propensity for a thing to be broken up into further things, so cannot be a primitive concept from which a ‘thing’ can be defined. As Armstrong puts it, this does not help to define a thing any more than it will help to define a cat by saying it is the offspring of two cats.

Impenetrability and hardness can also be analysed only in terms of their relations with other primary qualities (such as resistance to changes in shape and size) or with other physical objects. Finally, Armstrong attests that additions to the list of primary qualities by modern physics, such as mass and electric charge, cannot serve as fundamental defining concepts because they too dissolve into relations or dispositions to have relations that one particle has to another.

The conclusion which Armstrong draws from the above is that in order for a coherent account to be made of them, physical objects must possess a further quality (or qualities) over and above the traditional list of primary qualities. This extra quality must satisfy the following tests:

- it must not be analysable solely in terms of the other primary qualities (as in the case of motion).
- it must not be a relation that a physical object has with other physical objects (as in the case of divisibility and impenetrability). As alluded to above, this is because a property which is a relation between things cannot be a fundamental property, because in order to understand what the relation is, we already need to have an understanding of the thing.

Armstrong tentatively suggests that perhaps it is the secondary qualities which may satisfy these tests. But the traditional criticism of the view that secondary qualities inhere in the physical objects that they are dependent on the sensory apparatus of the observer. To see colours requires functioning eyes, to hear sound requires functioning ears and so forth.

Perhaps, then, what is required in exploring what the extra primary quality might be is to find what is common amongst the features of our different perceptions, and not dependent on the nature of the sensory organs.

Analysis of our perceptions shows a common feature they all share is their affective or emotional tone. The disgust of a foul odour, the beauty of a melody or harmony, the irritating or calming effect of colours, the soothing effect of a massage, the sweetness or bitterness of tastes- no matter what organ of the body our sensations are derived from, they are all accompanied by a certain affective tone.

Therefore, it may be that affective tone is the extra intrinsic quality which inheres in physical objects and allows a coherent account to be made of them. Affective tone certainly satisfies the two tests put forth by Armstrong - it is not analysable in terms of other primary qualities and is not a relations between physical objects.

However, two objections which will immediately arise to this suggestion are that firstly, emotions are produced subsequent to our perceptions and not part of what is perceived; and secondly, the affective tone of perceptions is dependent on the subjective state of the observer and so cannot be an intrinsic feature of what is observed. Each of these objections will be dealt with in turn.

Most people, scientists included, would regard it as common sense that emotions are produced in response to external stimuli, rather than being part of the actual stimuli. Surely, it is obvious that we perceive and then we emote. But is this view anything more than an unexamined prejudice?

In support of the view that it our brains the solely produce our emotions, evidence that stimulation of specific areas of the brain produces certain emotions could be adduced. For example, stimulation of a certain area of the frontal lobe produces feeling of spiritual transcendence, combine with a sense of some mystical presence. Similarly, stimulation of different areas of the amygdala produces feelings of rage, fear or a ‘warm,floaty feeling’ associated with appeasing behaviour. However, although examples such as these show that the exquisite architecture of the brain is attuned to the generation of certain emotions, they do not show that the brain is the only arrangement of matter capable of producing emotion.

Of course, the conscious experience of emotion is a complex phenomena. Emotional stimuli are registered by the amygdala, part of the primitive limbic system. Conscious emotion arises both by direct signals from the amygdala to the cortex and indirectly. The indirect path involves the sending of hormonal messages by the hypothalamus, which creates physiological changes such as increased blood pressure and heart rate. These changes are then fed back via the somatosensory cortex to the frontal cortex, where emotion is consciously experienced.

If, for simplicity’s sake, we focus on the direct pathway, we could ask in relation to the feeling aroused by a certain sight or colour, where does this feeling arise from? Does the amygdala or the cortex somehow transform the purely quantitative movement of energy and matter into a subjective quality? As Charles Birch has phrased it, “Nerve impulses to the brain don’t just miraculously become converted from electricity into feelings. In some way they must register the feelings of the cells of the retina... our feeling is the ‘feeling of feelings’ ”. Following this reasoning, the cells of the retina must, in turn, feel the feelings conveyed by the external stimulus.

In the future, neurophysiology may show that our emotional responses are in fact generated solely by the wiring of the brain, but in the meantime the possibility that part of the affective tone of our experiences is conveyed directly from the object perceived must be kept open.

With regard to the second objection, it is true that the affective tone of a perception is very much dependent on the state of mind of the observer. For instance, a depressed person may not experience as much joy at seeing a bunch of roses as the next person, and the capacity of different forms of music to produce emotions is very much a matter of personal taste.

However, as already stated, emotion is a complex physiological phenomena. Further, different emotions arise through different mechanisms. As neuroscientist Joseph Ledoux says, “each [emotional] system evolved to solve different problems that animals face and each has a separate neural basis”. Thus, the experience of emotion arises through multifarious routes and is very much dependent on the psychological and physiological state of the observer. But just as observers of a tree may see the tree differently but the tree is still there, so too the emotional substratum of a perceived object may still exist underneath the layers accreted by individual differences.

It might also be objected that the affective tone of a perception is dependent on our sensory organs because different aspects of a physical object may have different affective tones. For example, certain flowers may look attractive but have a unpleasant odour. However, physical objects are complicated affairs and what is happening in these instances is the perception of different physical ‘objects’. The affective tone of the odour is associated with certain molecules which arouse the olfactory organs, whereas the objects of sight are wavelengths of light.

Thus, affective tone may indeed be the primary quality of physical objects which enables them to be coherently characterised. Our strongest justification for our conception of matter may be that we feel its feelings.

This is something that can be tested and disproved by neurophysiology. Such testing may show that the emotions we experience are totally dependent on the activities of our neurons and not at all on the features of the physical objects perceived. Such evidence would show that emotions are, like secondary qualities, dependent on the physiological state of the observer. This would not mean that physical objects are necessarily devoid of affective tone. A “representationalist” form of affective panxperientialism could still be advanced. But it would mean that the argument for panexperientialism presented here would be void.

Lest it be thought that the subject matter of this post is too much out on a limb, I conclude with a quote from the respected philosopher David Ray Griffin:

“Whitehead’s view is that secondary qualities are produced by the mind out of values, or emotions. Recalling that such things are sometimes spoken of as ‘tertiary’ qualities, we could say that secondary qualities are produced by the mind out of tertiary qualities that are in the body and even nature in general... The qualities called primary in the dualistic and materialistic views are for him simply features of things as viewed from without.” (Unsnarling the World Knot p.141).


Armstrong DM, Perception and the Physical World, 1961, Routledge & Keagan Paul, London.

Birch C, Feelings, 1995, UNSW Press, Sydney.

Carter R, Mapping the Mind, 2000, Phoenix, London.

Griffin DR, Unsnarling the World Knot: Consciousness, Freedom and the Mind-Body problem, 1998, University Of California Press, California.

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