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12. Knowledge Sources / B. Perception / 2. Qualities in Perception / d. Secondary qualities

[qualities seeming to involve the observer]

32 ideas
Some objects of sensation are unique to one sense, where deception is impossible [Aristotle]
     Full Idea: Now I call that sense-object 'special' that does not admit of being perceived by another sense and about which it is impossible to be deceived.
     From: Aristotle (De Anima [c.329 BCE], 418a15)
Some knowledge is lost if you lose a sense, and there is no way the knowledge can be replaced [Aristotle]
     Full Idea: The loss of any one of the senses entails the loss of a corresponding portion of knowledge, and since we learn either by induction or by demonstration, this knowledge cannot be acquired.
     From: Aristotle (Posterior Analytics [c.327 BCE], 81a37)
     A reaction: This suggests Jackson's 'knowledge argument', that raw experience contains some genuine knowledge, for which there is no mechanistic substitute. Not that I accept….
Epicurus says colours are relative to the eye, not intrinsic to bodies [Epicurus, by Plutarch]
     Full Idea: Epicurus says that colours are not intrinsic to bodies but a result of certain arrangements and positions relative to the eye, which implies that body is no more colourless than coloured.
     From: report of Epicurus (fragments/reports [c.289 BCE], Fr 30) by Plutarch - 74: Reply to Colotes §1110
     A reaction: This seems to me such a self-evident truth that I am puzzled as to why anyone would claim that colours are real features of bodies. Epicurus points out that entering a dark room we see no colour, but then colour appears after a while.
Non-graspable presentations are from what doesn't exist, or are not clear and distinct [Stoic school, by Diog. Laertius]
     Full Idea: The non-graspable presentation is either not from an existing object or from an existing object but not in accordance with it; it is neither clear nor well stamped (i.e. distinct).
     From: report of Stoic school (fragments/reports [c.200 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 07.46
     A reaction: This sounds exactly like Locke's account of secondary qualities, at least as interpreted by Peter Alexander. That is, they are genuine qualities of things, but misleading, in a way that primary qualities are not.
Changes in secondary qualities are caused by changes in primary qualities [Giles of Orleans]
     Full Idea: Every alteration in secondary qualities is caused by some alteration made in the primary qualities.
     From: Giles of Orleans (On 'Generation and Corruption' [1270], I.6c)
     A reaction: Pasnau calls this the 'supervenience' thesis, here with the addition of causation. Was this doctrine retained by Locke and Boyle?
Heat and colour don't exist, so cannot mislead about the external world [Galileo, by Tuck]
     Full Idea: Galileo argued that there is no such thing as heat (and hence also as colour) in the external world, so there is no reason to conclude from colour-blindness that we cannot know the truth about the world.
     From: report of Galileo Galilei (Il Saggiatore ('The Assayer') [1623]) by Richard Tuck - Hobbes Ch.1
     A reaction: This key idea, taken up by Gassendi, Descartes and Locke, seems to me to be one of the most important (and, in retrospect, rather obvious) facts ever worked out by the human mind. Why does anyone still doubt it?
Tastes, odours and colours only reside in consciousness, and would disappear with creatures [Galileo]
     Full Idea: I think tastes, odours, colours, and so on are mere names as far as the objects are concerned, and only reside in consciousness. Hence if the living creature were removed, all these qualities would be wiped away and annihilated.
     From: Galileo Galilei (Il Saggiatore ('The Assayer') [1623]), quoted by Brian Ellis - The Philosophy of Nature: new essentialism Ch.3
     A reaction: A nice bold assertion of the primary/secondary distinction from the first great scientist. I agree, and to disagree (and hence side with Berkeley and Hume) is to head for metaphsical and epistemological confusion.
Our sensation of light may not be the same as what produces the sensation [Descartes]
     Full Idea: There can be a difference between our sensation of light and what is in the objects that produce that sensation in us.
     From: René Descartes (The World [1631]), quoted by Ian Dunt - How to be a Liberal 1
     A reaction: Note only that they 'may' differ, and that he does not assert that they are entirely different. Secondary qualities give information, and are not just mental events.
Boyle's term 'texture' is not something you feel, but is unobservable structures of particles [Boyle, by Alexander,P]
     Full Idea: Perhaps Boyle's most important technical terms is 'texture'. ...It must not be confused with the way we feel the texture of a surface like sandpaper or velvet; it is rather a structure of unobservable particles and so it is not directly observable.
     From: report of Robert Boyle (The Origin of Forms and Qualities [1666]) by Peter Alexander - Ideas, Qualities and Corpuscles 03.2
     A reaction: This is the basis for Alexander's reassessment of what Boyle and Locke meant by a 'secondary quality', which, he says, is a physical feature of objects, not a mental experience.
Boyle's secondary qualities are not illusory, or 'in the mind' [Boyle, by Alexander,P]
     Full Idea: There is no suggestion in Boyle that secondary qualities are, unlike primary qualities, somehow illusory, subjective or 'in the mind'.
     From: report of Robert Boyle (The Origin of Forms and Qualities [1666]) by Peter Alexander - Ideas, Qualities and Corpuscles 03.3
     A reaction: [Alexander goes on to say that his also applied to Locke]
In my view Locke's 'textures' are groups of corpuscles which are powers (rather than 'having' powers) [Locke, by Alexander,P]
     Full Idea: I take the unorthodox view that Locke uses the word 'texture' for the pattern of corpuscles in a group and regards the power of a body to affect our senses or another body as identical with this textures, so that powers are intrinsic properties of bodies.
     From: report of John Locke (Essay Conc Human Understanding (2nd Ed) [1694]) by Peter Alexander - Ideas, Qualities and Corpuscles 5.2
     A reaction: The disagreement is whether the textures 'have' the powers (the orthodox view), or whether they 'are' the powers (Alexander's view). To counter Idea 15971, Alexander quotes Idea 15974. He says 'a secondary quality is a texture' (121).
I suspect that Locke did not actually believe colours are 'in the mind' [Locke, by Heil]
     Full Idea: I make no claim to being a Locke scholar, but I suspect that the position often associated with Locke - that colours are 'in the mind' - flies in the face of Locke's considered view.
     From: report of John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.08.15) by John Heil - From an Ontological Point of View 17.3
     A reaction: A glance at Locke gives the impression that he thought secondary qualities were really 'ideas', which would presumably be in the mind. Heil is hoping that Locke will agree with his own view. Further study will be required...
Secondary qualities are simply the bare powers of an object [Locke]
     Full Idea: Secondary qualities, as has been shown, are nothing but bare powers.
     From: John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.23.08)
     A reaction: I'm not sure here whether 'bare' means 'simple' or 'unconcealed' - probably the latter. This supports Alexander's claim that the secondary qualities are identical to the 'textures' of the object. They certainly aren't in the mind.
We know objects by perceptions, but their qualities don't reveal what it is we are perceiving [Leibniz]
     Full Idea: We use the external senses ...to make us know their particular objects ...but they do not make us know what those sensible qualities are ...whether red is small revolving globules causing light, heat a whirling of dust, or sound is waves in air.
     From: Gottfried Leibniz (Letters to Queen Charlotte [1702], 1702)
     A reaction: These seems to be exactly the concept of secondary qualities which Locke was promoting. They are unreliable information about the objects we perceive. Primary qualities are reliable information. I like that distinction.
Secondary qualities conjure up, and are confused with, the sensations which produce them [Reid]
     Full Idea: The thought of a secondary quality always carries us back to the sensation which it produces.We give the same name to both, and are apt to confound them.
     From: Thomas Reid (Essays on Intellectual Powers 2: Senses [1785], 17)
     A reaction: 'Redness', for example. Reid puts the point very nicely. Secondary qualities are not entirely mental; they pick out features of the world, but are much harder to understand than the primary qualities. The qualia question lurks.
Colours and tastes are not qualities of things, but alterations of the subject [Kant]
     Full Idea: Things like colors, taste etc. are correctly considered not as qualities of things but as mere alterations of our subject, which can even be different in different people.
     From: Immanuel Kant (Critique of Pure Reason [1781], B045/A29)
     A reaction: This acceptance of the category of 'secondary' qualities shows that Kant is not totally daft about reality. He 'considers them as' alterations in the subject, but how does he view primary qualities? Not, I think, as features of the noumenon.
I can make no sense of the red experience being similar to the quality in the object [Kant]
     Full Idea: I can make little sense of the assertion that the sensation of red is similar to the property of the vermilion [cinnabar] which excites this sensation in me.
     From: Immanuel Kant (Prolegomena to Any Future Metaphysic [1781], 290)
     A reaction: A sensible remark. In Kant's case it is probably a part of his scepticism that his intuitions reveal anything directly about reality. Locke seems to have thought (reasonably enough) that the experience contains some sort of valid information.
Armstrong suggests secondary qualities are blurred primary qualities [Armstrong, by Robinson,H]
     Full Idea: According to D.M. Armstrong and others, when we perceive secondary qualities we are in fact perceiving primary qualities in a confused, indistinct or blurred way.
     From: report of David M. Armstrong (A Materialist Theory of Mind (Rev) [1968], 270-90) by Howard Robinson - Perception III.1
     A reaction: This is obviously an attempt to fit secondary qualities into a reductive physicalist account of the mind. Personally I favour Armstrong's project, but doubt whether this strategy is necessary. I just don't think there is anything 'primary' about redness.
Secondary qualities are microscopic primary qualities of physical things [Armstrong]
     Full Idea: I argue for the direct identification of the secondary qualities with microscopic primary qualities of physical things.
     From: David M. Armstrong (Pref to new 'Materialist Theory' [1992], p.xxii)
     A reaction: This sounds a bit like the eliminativism which Armstrong rejects. This seems in danger of mixing questions about the nature of mental events with questions about the nature of externally perceived objects.
Lockean secondary qualities (unlike primaries) produce particular sensory experiences [McGinn]
     Full Idea: In the Lockean tradition, secondary qualities are defined as those whose instantiation in an object consists in a power or disposition of the object to produce sensory experiences in perceivers of a certain phenomenological character.
     From: Colin McGinn (Subjective View: sec qualities and indexicals [1983], 2)
     A reaction: Primary qualities are said to lack such dispositions. Not sure about these definitions. Primaries offer no experiences? With these definitions, comparing them would be a category mistake. I take it primaries reflect reality and secondaries do not.
Could there be a mind which lacked secondary quality perception? [McGinn]
     Full Idea: Can we form a conception of a type of mind whose representations are free of secondary quality perceptions?
     From: Colin McGinn (Subjective View: sec qualities and indexicals [1983], 6)
     A reaction: Nice question. Minds must have experiences, and there has to be a 'way' or 'mode' for those experiences. A mind which directly grasped the primary quality of sphericity would seem to be visionary rather than sensual or experiential.
Secondary qualities contain information; their variety would be superfluous otherwise [McGinn]
     Full Idea: Surely we learn something about an object when we discover its secondary qualities? ...If secondary quality experience were informationally inert, its variety would be something of a puzzle. Why not employ the same medium for all primary informaton?
     From: Colin McGinn (Subjective View: sec qualities and indexicals [1983], 6)
     A reaction: This is important. We can't just focus on the primary qualities, and ignore the secondary. But diverse colours draw attention to information, which can then be translated into neutral data, as in spectroscopic analysis. Locke agrees with this.
The utility theory says secondary qualities give information useful to human beings [McGinn]
     Full Idea: Secondary quality perception, according to the utility theory, gives information about the relation between the perceptual object and the perceiver's needs and interests.
     From: Colin McGinn (Subjective View: sec qualities and indexicals [1983], 6)
     A reaction: Almost the only example I can think of is whether fruit is ripe or rotten. ...Also 'bad' smells. We recognise aggressive animal noises, but that is not the same as dangerous (e.g. rustling snake). Divine design is behind this theory, I think.
If objects are not coloured, and neither are sense-contents, we are left saying that nothing is coloured [Robinson,H]
     Full Idea: If there are good reasons for thinking that physical objects are not literally coloured, and one also refuses to attribute them to sense-contents, then one will have the bizarre theory (which has been recently adopted) that nothing is actually coloured.
     From: Howard Robinson (Perception [1994], 1.7)
     A reaction: It seems to me that objects are not literally coloured, that the air in between does not become coloured, and that my brain doesn't turn a funny colour, so that only leaves colour as an 'interior' feature of certain brain states. That's how it is.
Shape can be experienced in different ways, but colour and sound only one way [Robinson,H]
     Full Idea: Shape can be directly experienced by either touch or sight, which are subjectively different; but colour and sound can be directly experienced only through experiences which are subjectively like sight and hearing.
     From: Howard Robinson (Perception [1994], III.1)
     A reaction: This seems to be a key argument in support of the distinction between primary and secondary qualities. It seems to me that the distinction may be challenged and questioned, but to deny it completely (as Berkeley and Hume do) is absurd.
If secondary qualities match senses, would new senses create new qualities? [Robinson,H]
     Full Idea: As secondary qualities are tailored to match senses, a proliferation of senses would lead to a proliferation of secondary qualities.
     From: Howard Robinson (Perception [1994], III.1)
     A reaction: One might reply that if we experienced, say, magnetism, we would just be discerning a new fine grained primary quality, not adding something new to the ontological stock of properties in the world. It is a matter of HOW we experience the magnetism.
Phenol-thio-urea tastes bitter to three-quarters of people, but to the rest it is tasteless, so which is it? [Crane]
     Full Idea: Phenol-thio-urea tastes bitter to three-quarters of people, but to the rest it is tasteless. Is it really bitter, or really tasteless?
     From: Tim Crane (Elements of Mind [2001], 5.44)
     A reaction: A nice reinforcement of a classic Greek question. Good support for the primary/secondary distinction. Common sense, really.
Secondary qualities are just primary qualities considered in the light of their effect on us [Heil]
     Full Idea: Secondary qualities are just ordinary properties - roughly, Locke's primary qualities - considered in the light of their effects on us.
     From: John Heil (From an Ontological Point of View [2003], 14.10)
     A reaction: Unconvincing. If they only acquire their ontological status as primary qualities if they have to be considered in relation to something (us), then that is not a primary quality.
Colours aren't surface properties, because of radiant sources and the colour of the sky [Heil]
     Full Idea: Theories that take colours to be properties of the surfaces of objects have difficulty accounting for a host of phenomena including coloured light emitted by radiant sources and so-called film colours (the colour of the sky, for instance).
     From: John Heil (From an Ontological Point of View [2003], 17.4)
     A reaction: Personally I never thought that colours might be actual properties of surfaces, but it is nice to have spelled out a couple of instances that make it very implausible. Neon and sodium lights I take to be examples of the first case.
Although colour depends on us, we can describe the world that way if it picks out fundamentals [Fine,K]
     Full Idea: As long as colour terms pick out fundamental physical properties, I would be willing to countenance their use in the description of Reality in itself, ..even if they are based on a peculiar form of sensory awareness.
     From: Kit Fine (The Question of Realism [2001], 8)
     A reaction: This seems to explain why metaphysicians are so fond of using colour as their example of a property, when it seems rather subjective. There seem to be good reasons for rejecting Fine's view.
The colour bands of the spectrum arise from our biology; they do not exist in the physics [Sorensen]
     Full Idea: The bands of colour in a colour spectrum do not correspond to objective discontinuities in light wavelengths. These apparently external bands arise from our biology rather than simple physics.
     From: Roy Sorensen (Vagueness and Contradiction [2001], Intro)
     A reaction: If any more arguments are needed to endorse the fact that some qualities are clearly secondary (and, to my amazement, such arguments seem to be very much needed), I would take this to be one of the final conclusive pieces of evidence.
The taste of chocolate is a 'finer-grained' sensation than the taste of sweetness [Polger]
     Full Idea: The taste of chocolate is presumably a 'finer-grained' sensation than the taste of sweetness.
     From: Thomas W. Polger (Natural Minds [2004], Ch.1.4)
     A reaction: An interesting distinction when it comes to what they are like, and whether two very different brains can realise them. Sweetness might be the same for most creatures, but the tast of chocolate subtly different.