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Eliminativism and Fictionalism. Theoretical Entities Some things we can’t observe directly. We believe they exist because they are part of a theory that.

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Presentation on theme: "Eliminativism and Fictionalism. Theoretical Entities Some things we can’t observe directly. We believe they exist because they are part of a theory that."— Presentation transcript:

1 Eliminativism and Fictionalism

2 Theoretical Entities Some things we can’t observe directly. We believe they exist because they are part of a theory that best explains things that we can observe. These are called “theoretical entities.”

3 Atomic Theory For example, atomic theory posits that all of the ordinary objects of everyday life– tables and chairs and trees and humans and planets– are made out of extremely small, imperceptible atoms, about 117 different kinds, each with its own particular characteristics.

4 Inference to the Best Explanation Why do we believe the atomic theory (and therefore believe in atoms)? Put simply, the theory makes a large number of predictions, each of which we can observe to be true. Atomic theory predicts how various substances will interact, and we observe those substances interacting in those ways.

5 Mental States as Theoretical Entities We cannot see or hear or smell our beliefs or our desires. No scientific instruments (at present) can measure them. We cannot experience the emotions or sensations of other people. Why do we then believe in beliefs and desires and moods and tickles? Answer: They are part of a well-confirmed theory.

6 “Folk Psychology” “Folk psychology” is a name for a collection of platitudes regarding mental states. Examples: People who stand in front of trees in good light with their eyes open come to believe that there is a tree in front of them. If someone intends to eat dinner and believes that they cannot eat dinner unless they go to a restaurant, they will go to a restaurant.

7 Folk Psychological Predictions Folk psychology tells us what circumstances will cause people to have certain beliefs, desires, intentions, emotions, etc., and then also tells us what those mental states will cause those people to do. If we discover that in those circumstances, people act in the way the theory predicts, then we have confirmation of the theory.

8 Mental States as Best Explanation If the predictions of folk psychology are confirmed (we observe them to be true), then we have some reason to believe the theory. If no other, better theory comes along to explain the actions of animals and people, then folk psychology is the best explanation (at present), and we should probably believe it.

9 “Quantifying Over” Philosophers say that a theory “quantifies over” anything that exists, according to the theory. So the atomic theory quantifies over atoms and folk psychology quantifies over mental states. If we believe any theory that quantifies over mental states, then we believe in the existence of mental states.


11 False Theories Sometimes our theories turn out to be false, and are replaced with other theories. If the new theories do not quantify over the theoretical entities of the old theory, we say that those theoretical entities have been eliminated.

12 Note! Eliminated theoretical entities are not things that once existed, but now no longer exist (like dinosaurs). They are things that we once believed to exist, but now no longer believe to exist.

13 Conservative Theory Change Sometimes our new theories are “conservative” and don’t result in elimination of any theoretical entities. Example: In the past, humans thought that planets were stars. They had a false theory that quantified over planets. Now we know that planets are not stars, but our theory still quantifies over planets.

14 Radical Theory Change (Elimination) Sometimes, however, a theory is so wrong that our new theory no longer quantifies over the same things.

15 Phlogiston Theory

16 Phlogiston vs. Oxygen Theory As T-Rex explains, we had two competing theories: The phlogiston theory claimed that phlogiston was removed during burning, and thus that burnt substances lost mass. The oxygen theory claimed that oxygen was added to a burnt substance, and thus that burnt substances gained mass.

17 Eliminativism about Phlogiston As T-Rex also explains, we gave up the phlogiston theory when Lavoisier discovered that burnt things actually gained mass. Only the oxygen theory had confirmed predictions, it was the best theory. Today, scientists believe that phlogiston does not exist.

18 Second Example Humors

19 Churchland vs. Folk Psychology

20 Three Arguments for Eliminativism Ravenscroft presents three of Churchland’s arguments for eliminativism: 1.Folk psychology is a degenerative research program. 2.Folk psychology fails to illuminate many important features of our mental lives. 3.Folk psychology lacks extensive evidential links with the sciences.

21 Lakatos’ Philosophy of Science Imre Lakatos developed a model of how science worked. The primary element of the model was the “research program.”

22 Examples of Research Programs One example is Newtonian mechanics– the research program is to explain various physical phenomena by using Newton’s laws of motion. Another example is the research program of explaining derived traits in animals with the theory of natural selection.

23 Hard Core vs. Auxiliary Hypotheses Not every part of the theory or theories involved in a research program is treated equally. Some theoretical claims form the “hard core” of theory: to give them up is to abandon the theory. Other parts of the theory are not part of the hard core. It is possible to revise them, and still accept the theory. Sometimes changing these other claims is good, and leads to a better theory.

24 Progressive vs. Degenerative A research program is progressive if recent changes to its auxiliary hypotheses result in new and better predictions. It is degenerative if recent changes to its auxiliary hypotheses have only been made to save the hard core from being falsified

25 Example: Young Earth Creationism For a long time in the west, serious scientists believed that the universe was only about 6,000 years old (as related in the Christian bible). It used to be a genuine research program to understand the development of the natural world in the time-scale of the bible. Now it is not.

26 Example: Young Earth Creationism As we’ve collected more observations, we’ve found reason to believe it’s much older. Some trees have more than 11,000 tree rings. We can see light from stars that are billions of light years away. Additionally, other progressive scientific theories require an old Earth: evolutionary theory, plate tectonics, theories of radioactive decay, etc.

27 Example: Young Earth Creationism But there are still today young Earth creationists. They say, for example, that God created light already on its way from stars billions of light years away, so it would seem as if it came from them, when it didn’t (it came from < 6,000 light years away). Obviously such claims don’t add to the theory. They are just defenses against its bad predictions.

28 Folk Psychology as Degenerative According to Churchland, folk psychology is a degenerative research program. There is nothing that we believe about mental states that the ancient Greeks (for example) did not also believe, EXCEPT things we have been forced to accept to protect the hard core (unconscious beliefs, the unreliability of memory, etc.)

29 2. Folk Psychology is Unilluminating There are a wide range of phenomena that folk psychology has nothing interesting to say about. Why do we sleep? How does vision work? What makes someone creative? What are the best ways to learn?

30 3. Folk Psychology Does Not Connect with Other Sciences Progressive research programs interconnect with one another. For example, the evolutionary tree of life comes out the same whatever line of evidence you use: Current morphology Genetics Biogeography The fossil record

31 Folk Psychology Churchland claims however that folk psychology does not is not similarly supported by other successful scientific theories. Folk psychology, by definition, consists of the everyday platitudes about mental states that ordinary people accept. Most people don’t know anything about the sciences.

32 The Eliminativist Alternative If we accept the eliminativist arguments, what are we supposed to do? If we stop talking about mental states, how do we describe what we formerly called pains, and anger, and beliefs- that-it’s-Tuesday, etc.?

33 Neuroscientific Alternative One possibility is a turn to neuroscience. “I’m angry”  “My amygdala has more activity than usual.” “I love you”  “The oxytocin my brain has released has solidified my bond with you.” “I’m depressed”  “I have low levels of serotonin.”

34 Neuroscience Requires Mental States The problem with this strategy is that to do neuroscience in the first place requires you to believe in mental states. How do you find out that the amygdala is implicated in anger? You find people who are angry, and you see what’s happening in their brains.


36 Folk Psychology vs. Scientific Folk Psychology Ravenscroft rebuts the eliminativist arguments by distinguishing between folk psychology and what he calls “scientific folk psychology. Remember that we are only eliminativists if none of our theories quantify over mental states. Even if we reject folk psychology, we might still believe in mental states.

37 Scientific Folk Psychology Scientific folk psychology are those parts of scientific psychology that quantify over mental states– perceptions, sensations, emotions, beliefs, and desires. Lots of scientists– psychologists, neuroscientists, economists, etc.– have scientific theories that rely on the existence of mental states.

38 Scientific Folk Psychology Is Not Stagnant It’s reasonable to think that cognitive psychology has made lots of important new discoveries about mental states, and that it is becoming more predictive and explanatory of human and animal behavior. For example, we’ve discovered that the ability to understand that others can have false beliefs doesn’t arise until we’re about 4 years old.

39 Illuminating Examples Even if folk psychology does not explain vision or memory, that doesn’t mean it’s a radically false theory– it could just be incomplete. But there are lots of reasons to think that theories that quantify over mental states can explain a lot about memory, vision, etc.

40 Mental Illness Folk psychology may not have much in the way of illuminating mental illness, but this does not mean that scientific folk psychology is the same. For example, according to cognitive behavioral therapy, depression is caused by having a belief that you aren’t able to handle problems, when really you are. This is confirmed by the fact that CBT talk therapy is reasonably effective.

41 Vision Scientific folk psychology also has lots to say about vision. Vision science largely assumes that the visual system contains propositional representations, and logically infers the structure of our 3D environment, much like ordinary, conscious reasoning.

42 Memory Similarly, we’ve discovered lots of interesting things about memory: that there is short and long-term memory; that between 5-9 items can go in short-term memory; that the number of items can be increased by “chunking” them; that an item entering short-term memory is required for us to attend to it…

43 Links with Other Sciences Finally, although folk psychology, which is not a science, does not connect with other sciences– scientific folk psychology does. Neuroscience, linguistics, artificial intelligence, advertising…

44 Extraordinary Predictive Success There’s another argument for the existence of mental states that goes like this: the predictions of regular folk psychology are so amazingly powerful that it’s clearly the best theory and should not be replaced.

45 Neuroscience Predictions Imagine that a team of 1,000 top neuroscientists got to study my brain for a week– scanning my brain, hooking electrodes up to it, measuring chemical levels, whatever they wanted. With all their information, knowledge, and training, could they predict where I would be one week from today? No.

46 Folk Psychology Predictions But each of you can, right now, with no PhD’s and no million dollar machines, predict where I will be next week. Right here! Michael believes class meets here at the same time next week. Michael wants to go to class. People generally do what they believe will achieve their goals. So Michael will come to class.

47 Does Prediction Require Folk Psychology? Interesting question: do we need the mental states? Professors generally are in their classrooms at the times their classes are sheduled. Michael’s class is scheduled at this time. So that’s where he’ll be.


49 Fictionalism In philosophy, a fictionalist position is one where we deny the existence of a certain class of entities, while still maintaining that it’s useful to pretend that those entities exist.

50 Fictitious Forces It is difficult to do certain physics calculations on Earth, because the Earth is accelerating (everything not moving in a straight line is accelerating). It helps us do our calculations if we assume that certain forces exist (the Coriolis force and the centrifugal force), even though we know that they do not exist!

51 Fictionalist Positions in Philosophy Different philosophers have been fictionalist about a wide range of things: Good and evil Numbers Properties Probabilities Meanings Mental states

52 Ficitionalism about Mental States Dennett motivates his version of fictionalism about mental states by considering different explanatory “stances” we can take to things in our environment.

53 The Physical Stance Most things in our environment, including people and chess-playing computers, are made up of physical particles, and their behavior can be predicted by applying the laws of physics to them.

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55 Failures of the Physical Stance Often, the physical stance is impractical or even impossible for predicting certain behavior, given our current technology. Even though the physics of your laptop determines what will happen when you press the “p” key, it would be silly to try to work out the answer using the laws of physics.

56 The Design Stance In this case, we might instead use the design stance: predicting the behavior of an object based on what it was designed to do. The purpose of the “p” key on my laptop is to cause a “p” to appear on the screen. So I can reasonably predict that pressing it will cause a “p” to appear (though not if I just spilt water all over my keyboard).

57 Failure of the Design Stance The design stance frequently fails– often we don’t know what a thing is designed to do, even if it has a design. Evolution presumably selected our minds for certain purposes, but it can be difficult to explain those purposes in greater detail than “for survival.”

58 The Intentional Stance The intentional stance works by attributing certain beliefs and desires to people using the principles of folk psychology. People who stand in front of trees in good light with their eyes open come to believe that there is a tree in front of them. If someone intends to eat dinner and believes that they cannot eat dinner unless they go to a restaurant, they will go to a restaurant.

59 Fictionalism and the Intentional Stance How does this support fictionalism? Dennett points out that the intentional stance works even for many things that we know do not have mental states.

60 Example For example, we can explain the behavior of a certain chess-playing computer by attributing to it the desire to move its queen early in the match. If we look at the computer’s code, it may consist of just a bunch of mathematical formulas calculating the odds of winning: nothing about how the queen should move early.

61 Lesson This obviously doesn’t mean that we don’t have beliefs and desires. It does, however, present us with a model of how folk psychology could be very successful, even if the things it quantifies over don’t actually exist. But we need an independent reason for thinking they do/ don’t exist.

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