6.2 Problems with Resemblance

so what is the distinction between primary and secondary qualities it is not as Barkley and Hume thought that primary qualities are in objects and secondary qualities aren't that's not the distinction it's rather that the ideas of primary qualities are resemblances of them and their patterns do really exist in the bodies themselves but the ideas produced in Us by these secondary qualities have no resemblance of them at all there is nothing like our ideas existing in the bodies themselves so when I say that uh something a round yellow thing is round I'm attributing a property to it which resembles my idea the roundness of the object object and the roundness as it were as perceived by me are supposed to resemble whereas the yellowness of the object is not a resemblance of my idea at all my idea of yellow the phenomenal character of it the yellowness that I see is completely different from whatever it is in the object that causes that idea yellowness in the object is a matter we speculate of the micro structure the surface texture the corpuses the shape of the corpal how they're arranged the way that light reflects off them and so forth and its resemblance rather than presence in the object that distinguishes primary and secondary qualities okay now Barkley famously attacks lock on this as on many other things and Barkley wants to say that an idea cannot resemble an object an idea can be like nothing but an idea a color or figure can be like nothing but another color or figure so he attacks Lock's claim concerning resemblance he wants to say that ideas are as it were intrinsically perceivable there's something about them which just in their very Nature has to be perceived now I think this is very plausible with secondary qualities suppose for example you imagine the smell of lavender okay imagine that I've got some lavender Essence and I sprinkle it around the lecture theater and and you sniff it you get that smell that smell of lavender right Could That Smell exist outside of mind I don't mean the substance that causes the smell I mean the smell itself that could that exist outside of mind no surely not if nobody existed if there were none of us if there were no people to have that smell or no animals to have that smell then the smell would not exist even if the substance did it is plausible to say that nothing physical can be like a smell a smell is just intrinsically something which has to be in a mind has to be perceived in order to exist that's a very plausible claim okay now think about a color think about the yellowness of that light and I don't mean whatever it is that causes the yellow now I mean the perceived yellowness the phenomenal idea that you get think of the difference between yellow and red or blue or whatever it feels different to us it looks different can that look exist outside a mind plausibly not plausibly the look The phenomenal look what it is like to see it it can only exist by someone actually seeing it just as the smell can only exist by someone actually smelling it so if you think of things in that way Barkley's principle that for ideas there being is there being perceived seems very plausible but what about primary qualities we think well the roundness of the light what that's not the same okay I look at the light and I see it as round and I don't feel anything like the same reluctance to say that a real object can be round the roundness is not something that can only exist by being perceived at least that's it's our natural inclination to say that and Barkley wants to argue against that and in the case of primary qualities you you can see he's got much more of an uphill battle um arguing the point it doesn't seem that ideas of primary qualities have S quite the same intimate connection with being perceived with mentality and part of the reason is that they're more abstract and structural um we can use the abstract mathematical properties of shapes to think about them in a way that seems to correspond with the real world give an I'll give an example um imagine that you have a rectangle okay now imagine a diagonal line drawn from the bottom left corner of the rectangle to the top right corner of the rectangle now imagine a vertical line bisecting the re the rectangle so it's so it goes from the middle of the top to the middle of the bottom from the point where those two lines meet imagine a horizontal line being drawn to the right where does it cross the boundary of the rectangle and you will all say well halfway up the right hand side and you'd be right at least I hope so now we can do that sort of imagining we can imagine an idea and we think actually correctly that if we were to do that with physical objects and so on everything would work out we would find that the kind of thinking we're doing the structural thinking we're doing does seem to match up with physical objects in the world and that goes together with the fact that attributing to objects properties that are structurally similar to our mental picture of them does actually work which makes it quite plausible that the objects in themselves though perhaps you know in many ways ways very very different from our conception of them nevertheless have a sort of structural isomorphism a similar structure to the way we conceive of them at least in respect of their shape size and so forth if you want to read more on this uh Jonathan Lowe's book on lock the routage book uh discusses these sorts of issues um at the pages I've referred to there okay so we can make some sense of primary qualities in general like shape and size and motion resembling somehow our ideas of them it seems at any rate to make a lot more sense than the thought of uh primary qualities resembling a smell or a color but solidity seems to be a bit of an odd man out here okay so we've got a our nice divide between primary qualities secondary qualities we've got secondary qualities that seem seem to be intimately connected with perception we've got primary qualities which seem to be more abstract and structural and we seem to be able to make some sense at least of our ideas of primary qualities resembling primary qualities in the objects themselves but solidity does my idea of solidity resemble solidity in the object itself can I make any sense of that that's not so clear how do I get my idea of solidity well get it by kind of pushing against things or seeing one thing bash into another and knock it out of the way it looks like my only idea of solidity comes from seeing things behave in a particular way I don't seem to have any intrinsic idea of solidity in the way that I might do of a shape or a size or a movement so when we say that objects are solid it's not clear that we really understand in any intimate way what we're saying I mean solidity seems to be a power a disposition a way of Behaving it's the power to exclude other bodies so what's a body then well a body is something solid but if we can't understand solidity except as a power to exclude other solid bodies it looks like we're just going in a circle so here is David Hume uh attacking on precisely this line two non- entities cannot exclude each other from their places now I ask what idea do we form of these bodies or objects to which we suppose solidity to belong to say that we conceive them merely as solid is to run on in infinitum extension must necessarily be considered either as colored which is a false idea because it's a secondary quality which we're supposing not to be an object or as solid which brings us back to to the first question hence after the exclusion of colors and so forth from the rank of external existences there remains nothing which can afford US a just and consistent idea of body so what hum is saying here is the particular idea of solidity is highly problematic it doesn't seem to fit in to the category of ideas which we can coherently form as somehow re an idea of object as resembling the way we conceive of them and if you try to get an adequate conception of solidity you fail you have to think of a body as excluding other bodies but the only sense you can form of that is either to think of a body as a colored expanse or to think of it as a solid expanse the latter just gives you circularity the former brings you back to secondary qualities

Channel: University of Oxford

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Length: 10min 56sec (656 seconds)

Published: Thu Apr 14 2011