Think by Simon Blackburn. Chapter 7b The World

Transcription

1 Think by Simon Blackburn Chapter 7b The World

2 Kant s metaphysics rested on identifying a kind of truth that Hume and other did not acknowledge. It is called A. synthetic a priori B. analytic a priori C. synthetic a posteriori D. analytic a posteriori

3 Locke s view of primary vs. secondary qualities. Locke articulates the distinction between primary and secondary qualities on p.241, much as Galileo did in the previous passage. Blackburn invokes a more modern distinction: the manifest image: the way the physical world appears to us. the scientific image: the way science tells us the physical world really is. For Locke, the world really was just a bunch of particles. And, importantly, the motion of these particles is what science uses to explain how perception comes about. (p. 242)

4 Resemblance You should recall here Locke s previous talk of God s good pleasure, in attempting to grasp why a knife cutting the flesh feels the way it does. It is because colors, smells, tastes, and sounds are nothing in the objects themselves that Locke is driven to conclude that the way the world feels to us is God s good pleasure. He could have made it feel any way he wanted.

5 Berkeley You ll recall that Leibniz was quite upset with Locke about God s good pleasure, arguing that it violated the Principle of Sufficient Reason. (This is an intuition that Einstein later expressed in his rejection of the indeterminacy of quantum mechanics: God does not shoot dice with the universe. ) Another very important critique of Locke s views came from an Irish philosopher named George Berkeley. Basically Berkeley asked how we know that primary qualities are real. How do we know that our ideas of bulk, figure, texture, motion, quantity, extension, solidity, etc. represent reality itself?

6 Locke s answer Locke answers this question by examining the concept of solidity on p Basically, solidity comes down to the power to exclude other objects from a region of space. This is a nice definition, but what Berkeley is asking is not for the definition of solidity, but how we come to know about it. And Locke is very clear on p. 245: We feel it.

7 The problem It s not to hard to see the problem now. First, if we know about solidity by feeling it, why isn t solidity a secondary quality? Why should our sense of touch be given some special metaphysical privilege over sight or hearing? Second, Berkeley claims, ideas like solidity, motion, extension, etc. only make sense as properties of a body, some material thing. But what is left of our concept of any material thing if we actually remove all the secondary qualities? What sense does it make to talk about solidity all by itself?(p.246).

8 Which of the following is not one of Berkeley s criticisms of Locke s distinction between primary and secondary qualities? A. The existence of secondary qualities is just as certain as the existence of primary qualities. B. The reason for thinking that secondary qualities aren t in the world applies to primary qualities as well. C. The idea of a material object missing all of its secondary qualities does not make any sense.

9 A response to Berkeley Berkeley, Hume and others argued against Locke s distinction between primary and secondary qualities by claiming that the object disappears from our imagination when it is stripped of all it s secondary properties. But one surprisingly simple way to respond to this is just to deny that any image of the object is required for scientific understanding. For example, we can only perceive objects in two dimension and can only imagine them in three. But physics currently countenances 10 or more spatial dimensions.

10 Faraday Blackburn quotes Michael Faraday, the great physicist here on p What Faraday is saying is that the only thing we really know about physical objects is how they move about and react to one another. What we call a physical object is really just a short hand for a collection of forces. e.g., for something to have mass is just for it to deform a spring a certain distance. We don t see the mass of an object, we just see how far it moves the spring.

11 May the forces be with you The problem with this way of looking at things is nicely captured by Blackburn, again on p : Normally when we think of forces or things like gravitational or magnetic fields we take some notion like that of a particle for granted. We understand the existence of a field or force at some point in terms of the acceleration that would occur if some particle had been put here. But if...we resolve particles themselves into yet further powers...we cannot be satisfied with this kind of image. We have to try to understand the cosmos without the mental crutch afforded by things of any kind whatsoever.

12 Manifest image vs. scientific image So, to return to the distinction between the manifest image and the scientific image, the whole notion of a particle as a discrete, tangible, chunk of matter is part of the manifest image, not the scientific image. At the scientific level, particles disappear, and are simply replaced with mathematical equations representing forces, fields, and probabilities.

13 The claim that we can have no conception of an object stripped of it s secondary qualities is intended as a critique of which philosopher s view? A. Berkeley B. Hume C. Locke D. Descartes

14 Which of these is not a response to the criticism that we can have no conception of a thing stripped of it s secondary qualities? A. Whether or not an object is real does not necessarily depend on whether we can imagine it. B. The scientific image of the world does not actually consist of things at all. C. The distinction between primary and secondary qualities was never meant to be taken literally.

15 Summarizing Berkeley s critique Berkeley rejects Locke s distinction between primary and secondary qualities, essentially arguing that if secondary qualities are simply the contribution of consciousness, then primary qualities must be as well. Berkeley also believes that the claim that some of our ideas resemble the external world is basically incoherent. He famously claims that the only thing that can resemble an idea is another idea. In other words, it simply makes no sense to say that an idea resembles, or accurately represents, a completely unconceptualized reality.

16 Idealism Despite the power of Berkeley s critique, his resulting metaphysical view is highly problematic. Essentially, Berkeley concludes that there is no such thing as an objective physical reality at all. Reality is ideas and nothing more. This view is called idealism.

17 Avoiding subjective idealism Berkeley s view seems to be equivalent to the kind of solipsism or subjective idealism that Descartes was left with after the failure of his project in the Meditations. Moreover, it seems to imply that in absence of any sentient beings there would be no universe at all, which strongly conflicts with scientific view that sentient beings evolved from a pre-existing universe and that this universe will continue to exist when we are gone. Berkeley tried to solve this problem by invoking God as an infinite mental or spiritual substance, that is constantly perceiving everything.

18 2 limericks Critique There was a young man who said God, must find it exceedingly odd when he finds that the tree continues to be when noone's about in the Quad. Reply Dear Sir, your astonishment's odd I'm always about in the Quad And that's why the tree continues to be Since observed by, yours faithfully, God

19 Berkeley s own views are no less problematic than Locke s because they seem to imply that A. God does not exist. B. The external world does not exist in the absence of sentient beings. C. Primary and secondary qualities are both purely physical in nature.