Think by Simon Blackburn. Chapter 7a The World

Transcription

1 Think by Simon Blackburn Chapter 7a The World

2 What s real? This chapter basically concern the question: What is real? Of course, everything is real in some sense of the word. Your dreams, hallucinations, beliefs, theories, ideas, and perceptions are real in the sense that they actually exist. So when we ask the question What is real? we are really asking to what extent ideas about the world reflect the way the world is, rather than just the way it appears to us. This inquiry into the fundamental nature of reality is what philosophers call metaphysics.

3 The old days vs. nowadays In the old days, before the invention of experimental science, the only way to answer such questions was to think very hard about them (rationalism!) Today, however, it is generally acknowledged that in some very basic sense figuring out what is real and what is not is the task of experimental science. Perhaps the main role of philosophy is to reveal the assumptions and methods by which science establishes for us what is real, and to show how this challenges the presuppositions of the ordinary person. We have already seen this process at work. e.g., the ordinary person tends to assume that the mind is a real thing distinct from the body, but science offers no support for that assumption.

4 Philosophy vs. Science? We should also note that there are still some philosophers who reject (and resent) the hegemony of science. They will argue, (as you might) that if their experience tells them one thing and science tells them another, then they will trust their experience. This attitude is not completely mistaken in the sense that a lot of what people wrongly think of as scientifically established is really just a random study that seems to support their prejudices. But to the extent that people actually think they are the best judges whether their child needs has a life threatening disease; being rich will make them happy; they are in control of their car while texting; humans evolved from primate ancestors; humans are causing climate change. well, this is just the result of ignorance. Scientists may not have the answers to all these questions, but in that case non scientists don t either

5 Metaphysics is the study of miracles. A. True B. False

6 Philosophy alone can determine the true nature of reality. A. True B. False

7 Galileo This chapter begins with an important quote by the astronomer/philosopher Galileo (p. 234). Galileo is expressing an important distinction between primary and secondary qualities. Primary qualities are part of the very nature of material things themselves: shape, size, location, motion, quantity, extension, solidity. Secondary qualities are not in material objects themselves, but only in the mind: color, taste, sound, odor, texture

8 Thinking about this Most of you already understand this. e.g., you probably don t think of sourness as being in the lemon. We say The lemon is sour, but what we really mean by that is that the lemon gives rise to a certain sensation that we call sour There are only 5 or 6 different tastes: bitter, salty, sour, sweet, yummy (and maybe fattiness). yummy is actually umami which means yummy or tasty in Japanese. Most of what we call flavor is not taste, but a complicated combination of taste and smell.

9 Colors It is a little harder for us to feel the subjectivity of color. Again, most of us appreciate the fact that material objects themselves are not actually colored. According to physics, and the theory of color vision, color perception is the result of specialized cells (rods and cones) in our eyes being stimulated by electromagnetic radiation of various wavelengths (between 400 and 700 nm). The important thing to realize is that EMR is not itself colored; rather, it produces color sensations in us.

10 Which of the following is not a secondary quality? A. red B. sour C. square D. loud

11 The difference between a primary and a secondary quality is that A. primary qualities are more obvious than secondary qualities. B. primary qualities are more observable than secondary qualities. C. primary qualities are the result of sensation, but secondary qualities are in the world. D. secondary qualities are the result of sensation, but primary qualities are in the world.

12 Locke The distinction between primary and secondary qualities was most ably articulated by John Locke, and it gave scientific validity to an old idea: There could be creatures who experience the world very differently from us. We dealt with this question already when talking about zombies and mutants. Z&M s are actually a very extreme version of this idea, though. The more realistic version is simply that that there could exist creatures whose sensory equipment makes them sensitive to very different aspects of the environment, and who would have qualitatively different perceptions as a result. Of course, we now know that this is true. (Bats, birds, snakes, etc. all have a wider range of sensitivity to the environment than humans do in on way or another.)

13 Perceptual relativity This view gives rise to what we now call perceptual relativity. There are two ideas here: (a) different creatures might (or actually do) perceive the world differently. (b) it is possible that one way of perceiving the world is no better or more accurate than another. This second point is something we need to be careful about. For example, dog s hearing is actually much better than human hearing; dog s sight is actually much worse than human sight. So dog perception is better that human perception in some ways and worse in others.

14 Understanding perceptual relativity On p. 240 Blackburn summarizes a way of thinking about the idea that two creatures O and O* might have different but equally good perceptions along some sensory dimension D: O and O* may live equally efficient, adapted lives in respect of sensory dimension D. The idea here is simply that for perceptions to be equally good they must be of equal value with respect to survival and other practical interests.

15 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)

16 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.

17 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?

18 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.

19 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).

20 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.