Quick Overview of Primary and Secondary Qualities

In order to get a better understanding of what Berkeley and Russell are talking about when they refer to primary and secondary qualities, lets look at each in turn.

When we perceive (or imagine) an object, it has a whole collection of properties.  For example, when I look at my car I perceive the following properties in various ways: the color (red), extension (i.e., volume/occupation of space), temporal location, spacial location, shape, texture, temperature, motion, quantity, and sound.

Some of these qualities are subjective in nature and some are objective.  That is to say, some of the qualities appear the way the do as a consequence of how my brain is wired and how my perceptual system works, and some are actual qualities of the objects "out there" that I'm perceiving.

If my brain had been wired differently, the subjective qualities might have appeared differently. For example, maybe my car has been sitting in the sun all day so when I touch it, it has the quality of "warmness."  But "warmness" isn't an actual quality of my car; that fact that I feel warmness is a consequence of how my fairly standard human perceptual system is calibrated to perceive an object's average kinetic energy (i.e., motion).

We can bring the subjective nature of temperature out by considering what would happen if some aliens from Mercury were to touch my car.  Their perceptual system is (most likely) calibrated differently from mine and so, upon touching my car, they might perceive my car's temperature as cold.  The central idea is that the warmth or coolness of my car isn't "in" the car--it's in how I perceive the car when I touch it.

Consider again those same aliens perceiving my car.  Regardless of how their perceptual apparati are wired, they will perceive my car as existing in a spacio-temporal location, of having a shape, and of being solid.  No amount of different wiring could change that.  They could fail to perceive these qualities, like a blind person does, but barring blindness, they could not perceive them in any way other than how they actually are in the object.

So, what inference can we draw from this?  It seems that there are certain properties that are mind-dependent (i.e., subjective) and other properties which are objective--that is, they are properties of the object itself.

Lets look at one more example of a subjective property: color.  Is my car, i.e., the car itself actually red or is the redness a consequence of how my brain interprets certain neuro-chemical signals?  While there is a small minority who disagree, most philosophers and perceptual psychologists will say that the object itself isn't red, it only appears red because of the way my brain interprets the electro-chemical signals which are cause by light waves of a certain frequency.

For example, red light has a frequency of 4×1014 Hz.  The light itself isn't red, my brain simply interprets light at that frequency as red.  However, it's totally conceivable that our brains could have interpreted that very same frequency as purple.  The point is that it is our minds (via our perceptual systems) that add color to whatever we are perceiving.  Color isn't "out there" it's "in here" (I'm pointing at my head).  

So, why does all this matter?  For modern philosophers there is a (fairly) clear distinction between primary and secondary qualities.  Primary qualities like extension, shape, quantity, and motion exist in the objects we are perceiving; they are part of the physical reality--i.e., they are objective.  Any two types of beings who perceive the same object will agree on the nature of that objects primary qualities.  For example, it's not possible for 2 people to look at a circle and for one to perceive it as a triangle.  Shape is a primary quality; it's not in the mind, it's inherent in the object.

Secondary qualities are color, sound, texture, and smell. These are qualities our mind adds to the objects we are perceiving.  Secondary qualities are mental; they do not exist in the external objects of perception.

Anyhow, this should help with understanding some of what Berkeley and Russell are discussing.

What Does "Bigger Than" Look Like in the Mind? Part 1 Locke's Ideas

The Prolem: Are All Locke's Ideas Necessarily Imagistic?

     Those of you who are facebook friends know I that I recently posted about a little issue I'm having wif my Locke paper.  Here's the prolem: most of my analysis and criticisms of Locke's epistemology rest on the premise that, for Locke, all ideas are images in the theatre of the mind.  I've read a couple of secondary sources that corroborate this interpretation but after frantically scanning my paper last night I realized that I don't a any direct quote from Locke to support this assertion.  

     Now, it is fairly evident that he thinks ideas caused by sense perception are images but Locke is aware that there are other types of ideas.  Locke says we get all our ideas one of two ways: through sense perception or through reflection.  By reflection he means comparing, mixing, and abstracting from the sense perception ideas.  For example, I have an idea (image) of a chair and of a large chair.  By comparing these two ideas I can create the new ideas of size and relative size, or "big" and "bigger than".  That much is clear in Locke, but what isn't clear is the phenomenological (what-it-is-like-to-have-ness) properties of the ideas size or "bigger than".  Another way to state it would be to ax, what does it mean to experience ideas of concepts?  This is the prolem I'm having; I'm not sure what Locke thinks about this...so, it's time to do a little reading of the primary "litra-cha".

Ideas Produced by Sense Perception

     Lets start with what I know, or at least what I think I know about how Locke thinks about ideas produced by sensory perception (did you get all that?).   The relevant passage is this, "But our ideas being nothing, but actual perceptions in the mind, which cease to be any thing, when there is no perception of them [...]".  So from here it appears fairly easy to ascribe an imagistic theory of mind to Locke but now I'm not so sure.  Sure he says ideas are perceptions in the mind but does this necessarily mean the perceptions have to be images?  I don't think this passage on its own is sufficient to make that case.

     Lets consider some of the language he uses to talk about perceiving ideas, in the context of memory, that occur in this same paragraph.  He says the purpose of memory is to "revive again in our minds those ideas, which after imprinting have disappeared, or have been as it were laid aside out of sight".  To talk of ideas "laid aside out of sight" certainly sounds imagistic, but notice he qualifies the phrase with, "as it were" in order to indicate an analogy, not a statement of fact.  Still no verdict.

     However, later in the paragraph, again discussing the purpose of memory, he says that memory allows us to "bring in sight, and make appear again, and be the objects of our thoughts, without the help of those sensible qualities, which first imprinted them there".    Again, phrases like "bring in sight", "make appear again" and "objects of our thoughts" sound very imagistic but there is no reason why Locke my not be using them as analogies.  In particular the phrase "objects of our thoughts" does not necessarily imply images, he might simply be saying "the content of the idea about which we are conscious".  I can't see why this commits him to an imagistic theory of mind, or even a phenomenal theory of mind.  

     He could be just about any brand of representationalist.  All he's really saying is that there is something in the content our perception of 'X' and in our recalling our perception of 'X' that are similar (the same?).  Maybe in the case of sense perception we can ascribe an imagistic or phenomenological theory to Locke but there's nothing that unusual in saying our memory of a perception and the actual perception have some imagistic qualities in common.  In regards to ideas and recollections of concepts, however, I don't think we have any evidence one way or another to determine Locke's position....more research