Sunday, March 18, 2018

Mental States are Causally Irrelevant on Naturalism (p. 4)

[This page is no longer valid]

Mental States are Causally Irrelevant on Naturalism (p. 3)

[This page is no longer valid]

Mental States are Causally Irrelevant on Naturalism (p. 2)

Home > Philosophy > Metaphysics
  1. Problems for Naturalism
  2. Why Mental States are Causally Irrelevant on Naturalism

Why Mental States are Causally Irrelevant on Naturalism



To define some terms, “logically impossible” means impossible by virtue of self-contradiction, so anything that’s not self-contradictory is logically possible. For example, a magical unicorn is logically possible, but a married bachelor isn’t. “Naturalism” is the denial of the supernatural, such that a “naturalistic universe” is a universe where naturalism is true. A “mental state association set” is a set of associations where certain physical items (such as brains) have certain mental states associated with them.

Suppose we define a “physical state” as the universe’s physical conditions and the laws that govern it at some particular time. The naturalistic mental states (NMS) theorem, which the EAAN paper proves in section 2.2, effectively says that given any physical state for a logically possible naturalistic universe, no matter which logically possible mental state association set would obtain for that state, the universe’s outcome would still be the same. Thus, mental states are a causally irrelevant and useless byproduct of physical processes in the sense that no matter which mental state association would obtain for the physical world at a given time, it would not alter the universe’s resulting outcome.

Although the scholarly EAAN paper gets pretty technical (using math and formal logic) in arguing for mental states being causally irrelevant using something called the naturalistic mental states theorem (proven in the paper), the gist of why mental states are causally irrelevant on naturalism is actually pretty simple. Say that initial physical conditions are the initial conditions as specified in the domain of physics (types of particles, number of particles, their arrangement, etc.), that laws describe how the physical stuff (in the domain of physics) behaves in the absence of supernatural intervention including specifying the physical outcome of what will happen (e.g. where certain particles end up) given certain initial physical conditions in the absence of supernatural intervention[2], and that a physical state is the initial physical conditions and the laws that govern them.

Insofar as chemistry is reducible to physics (in that chemistry describes how certain combinations of the entities in physics behave with each other; e.g. how molecules interact with other molecules) the laws will consequently include the laws of chemistry. Insofar as biological systems like amoebas are merely very complex combinations of the entities of physics including molecules, those biological systems will include systems of chemistry and physics.

Now consider the following thought experiment: suppose on naturalism a given physical state (one that consisted of one person or many persons in the universe) were to have an entirely different set of mental states associated with this same physical state. Would the outcome be any different? It would not, because the same physical state means the same initial physical conditions and the same laws, so by definition we would get the same physical outcome in the absence of any supernatural intervention to change how things would go. On naturalism, if a different mental state (or no mental states) were associated with a given physical state, we’d get the same physical outcome (e.g. the same behavior) and on naturalism mental states are causally irrelevant in the sense that it doesn’t matter which mental state (if any) is associated with a given physical state; we’d still get the same physical outcome. We can structure this reasoning with the following argument:
  1. On naturalism, the following is true: If a physical state had any different set of mental states associated with it, the same outcome in the physical world (e.g. one’s behavior) would result.
  2. If (1) is true, then mental states are causally irrelevant on naturalism.
  3. Therefore (On naturalism), mental states are causally irrelevant.
Justification for (1): Physical states comprise of the initial physical condition and the laws that, by definition, say which physical outcome will occur given those initial physical conditions in the absence of supernatural intervention. Consequently, it would be self-contradictory on naturalism (which says there is no supernatural intervention) to have the same physical state (i.e. same initial physical conditions and the same laws) but a different physical outcome. So on naturalism, if a different set of mental states were associated with the same physical state, the same physical outcome would result.

Justification for (2): By “mental states are causally irrelevant” I mean in the sense that in the sense that it doesn’t matter which mental states the physical processes generate, and it doesn’t matter which set of mental states (even an empty set) is associated with the physical state of the world: it wouldn’t change the physical outcome (e.g. the same behavior would result). So essentially (2) is true by definition by what I mean by “mental states are causally irrelevant.” (One could mean something different by the phrase “mental states are causally irrelevant,” but this is what I mean by it.)

I suspect this sort of argument would convince most people, but some people (probably naturalists) can be remarkably resistant to the idea that mental states are causally irrelevant on naturalism in the sense that I described, and for such people the scholarly EAAN paper helps with via a rigorously proven theorem.

Conclusion



On naturalism, mental states are causally irrelevant in the sense that which mental states are associated with the physical states wouldn’t affect the outcome. The NMS theorem effectively says that given any physical state for a logically possible naturalistic universe, no matter which logically possible mental state association set would obtain for that state, the universe’s outcome would still be the same. This sort of causal irrelevancy poses (at least) two problems for naturalism. On naturalism, the mental content of a brain state (i.e. the mental state that’s associated with the brain state) doesn’t have anything to do with why its causal behavior is the way it is, whereas common sense suggests a mind’s mental content does have something to do with why it causes stuff. Another problem is that mental states being causally irrelevant in the way I suggested leads to Pr(R|N&E) being low (the Probability Thesis of the EAAN). It seems to me then that mental states being causally irrelevant on naturalism poses a serious problem to naturalism.

< Prev   |   1   |   2   |   Next >




[2] What if the outcome is random, such that (for example) there is exactly a 50% chance of a certain particle undergoing radioactive decay within a specified time period? In that case, the “outcome” would be something like “there is a 50% random chance that the particle undergoing radioactive decay within that time period such that on average, it will (randomly) decay 50% of the time.”

Mental States are Causally Irrelevant on Naturalism

Home > Philosophy > Metaphysics
  1. Problems for Naturalism
  2. Why Mental States are Causally Irrelevant on Naturalism

Problems for Naturalism



Naturalists typically believe that brain states determine mental states. Roughly, the gist of what I mean by mental states being causally irrelevant on naturalism is that on naturalism it doesn’t which mental state is associated with a brain state; the brain’s causal behavior would be the same even if no mental state were associated with it. The upshot is that if naturalism is true, mental states getting associated with our brain states is a causally irrelevant and useless byproduct of our biological processes. This raises problems for naturalism.

We normally think that our mental states (elements of mental states include sense experiences, memories, thoughts, etc.) have something to do with our behavior; e.g. a mental state yielding the belief that I am thirsty and this water will quench my thirst will yield different behavior, ceteris paribus, then if my mental state instead yielded the belief that This water will kill me and I don’t want to die.[1] If our mental states are causally relevant to behavior, and on naturalism mental states are not causally relevant to our behavior, then naturalism is false.

Another problem is that mental states being causally irrelevant on naturalism implies that the likelihood of a humanoid’s cognitive faculties being reliable given naturalism and evolution are low. I went into this in my debate on the evolutionary argument against naturalism (EAAN), and go into mathematical detail in a scholarly paper on the evolutionary argument against naturalism, but I can start with a thought experiment about aliens that are humanoid (not only in having a human shape but also human-level intelligence in terms of complexity of thought, can form beliefs, change beliefs, etc.) whereby naturalism and evolution are true for them but we know little else.

What can we know from naturalism and evolution being true for these aliens? Natural selection selects for advantageous behavior, but not necessarily for true beliefs. If on naturalism the mental states of the alien humanoids are causally irrelevant, then when the alien brains that produce advantageous behavior also produce a mental state, none of the many conceivable mental state associations with the alien brains—even “garbage” mental states unrelated to their external environment (as in dreams)—would affect behavior. Garbage mental states vastly outnumber accurate mental states (i.e. those that accurately reflect one’s external reality), so while it is possible that the alien mental states are accurate, given just the information we have from evolution and naturalism (garbage mental states vastly outnumber accurate mental states, mental states are a causally irrelevant and useless byproduct the biological process, etc.) it would be a very serendipitous coincidence that the alien brain states that generate advantageous behavior also happen to generate accurate mental states, and it seems more likely that our aliens are effectively living in a dream world. Thus, the likelihood that the alien cognitive faculties are reliable given just the information we have (naturalism and evolution) is low.

We could use the results of this alien thought experiment in an argument for the reliability of our cognitive faculties being unlikely on naturalism and evolution. Before delving into the argument, here’s the basic symbolization key:

R = Our cognitive faculties are reliable
N = naturalism is true
E = evolution is true
Pr(R|N&E) = the probability of R given N&E


Borrowing from a bit the EAAN debate I was in and the scholarly EAAN paper, the argument that Pr(R|N&E) is low with RA representing “the cognitive faculties of the aliens are reliable” is this:
  1. If Pr(RA|N&E) is low, then Pr(R|N&E) is low.
  2. Pr(RA|N&E) is low.
  3. Therefore, Pr(R|N&E) is low.
Justification for (1): What’s true for the humanoid aliens here is also true for us, since we are basically considering the probability of R on just N&E (we considered Pr(RA|N&E) merely so we could try thinking about the issue in a way that avoids bias towards our own species).

Justification for (2): Here’s what we know about our alien species on N&E:
  1. Mental states are a causally irrelevant and useless byproduct of the biological process.
  2. Garbage mental states vastly outnumber ones that accurately resemble one’s external reality.
  3. We have no a priori reason to believe an alien would have an accurate mental state (one that accurately reflects their external reality) instead of one of the far more numerous garbage mental states.
We’re basically trying to evaluate the likelihood of RA given just N&E, so points (a), (b), and (c) together suggest that given just the information we have here, it is considerably more likely that the aliens have unreliable cognitive faculties (garbage mental states being far more numerous) than reliable ones.

In the EAAN, the claim that Pr(R|N&E) is low is called the Probability Thesis, and the claim that the naturalist who sees that Pr(R|N&E) is low undercuts the naturalist’s justification for believing R is called the Defeater Thesis. Mental states being causally irrelevant on naturalism suggest that the Probability Thesis is true. I explained why I think the Defeater Thesis is true in the debate on the evolutionary argument against naturalism (you can also see page 2 of the EAAN debate recap if you want it summarized).

Thus if on naturalism mental states are causally irrelevant, this poses major problems for the naturalist. First, it seems to be true that our mental states are causally relevant. Second, mental states being causally irrelevant suggest that Pr(R|N&E) is low, which is a major component of using evolution to argue against the rationality of naturalism (if naturalism intellectually undercuts itself via evolution, that’s very bad for naturalism!). But why think that on naturalism, our mental states are causally irrelevant?

< Prev   |   1   |   | 




[1] I’m using “yield” to get around technical difficulties of semantic externalism I explained in my previous post-debate EAAN article. Basically, the issue is that people can have identical mental states but the semantic content of their beliefs can be different due to different referents. For example, consider two planets with identical inhabitants possessing identical mental states, and each say, “The sun is bright” when pointing at their sun, but the phrase “The sun” refers to different objects on those two planets. Nonetheless, a person’s mental state obviously plays a role in what beliefs they have and whether those beliefs are reliably true; e.g. the sort of mental states one has in chaotic dreams do not align with one’s external reality particularly well.

Saturday, March 17, 2018

Post-EAAN Debate Reflections (p. 3)

Post-EAAN Debate Reflections
< Prev   |   1   |   |   3   |   Next >

The Debate



Property Dualism



Epiphenomenalism is the view that states that consciousness and other mental states are a mere accessory to the neurophysiological processes whose presence or absence makes no difference. Semantic epiphenomenalism (SE) says that beliefs have two properties: syntax (the neurophysiological or NP properties) and semantic (e.g. the belief that p for some proposition p, e.g. the belief that Snow is white). A minor point, but at around 50:33 to 50:58 Spencer disagreed with me that SE makes this dualist property claim, and that I was going against how Plantinga described it. From pages 6 through 7 of Naturalism Defeated?
A second possibility is semantic epiphenomenalism: it could be that beliefs have causal efficacy with respect to their behavior, but not by virtue of their content. Put in currently fashionable jargon, this would be the suggestion that beliefs are indeed causally efficacious, but by virtue of their syntax, not by virtue of their semantics. On a naturalist or at least a materialist way of thinking, a belief could be something like a long-term pattern of neural activity, a long-term neuronal event. This event will have properties of at least two different kinds. On the one hand, there are its neurophysiological or electrochemical properties: the number of neurons involved in the belief, the connections between them, their firing thresholds, the rate and strength at which they fire, the way in which these change over time and in response to other neural activity, and so on. Call these syntactical properties of the belief. On the other hand, however, if the belief is really a belief, it will be the belief that p for some proposition p. Perhaps it is the belief that there once was a brewery where the Metropolitan Opera House now stands. This proposition, we might say, is the content of the belief in question.[2]
So, I was right.

Semantic Externalism



In about 20:33 to 24:01 of the debate my interlocutor (Spencer Hawkins) tried to use semantic externalism to attack premise (1) of this argument:
  1. (On naturalism) If a belief’s associated NP properties had any different semantic content associated with it instead, the same outcome in the physical world (e.g. one’s behavior) would result.
  2. If (1) is true, then a belief’s semantic content is causally irrelevant (on naturalism).
  3. Therefore (On naturalism), a belief’s semantic content is causally irrelevant.
What is semantic externalism? To explain I’ll use the famous Hilary Putnam’s famous Twin Earth scenario. His scenario goes something like this (I’ve modified it only slightly): suppose there is a Twin Earth that is identical to ours prior to the discovery of water being H2O except what its inhabitants call “water” is actually a complex chemical compound XYZ that looks and behaves just like water (rain has XYZ instead of water, lakes have XYZ instead of water, etc.). Let’s go back to 1750 before we learned the chemical composition of “water” is H2O. Two individuals, one on the actual Earth and one on Twin Earth, have identical mental states when they think, “That over there is water.” Nonetheless, in a way the sentences “That over there is water” have different semantic content between Earth and Twin Earth because they each refer to different chemical substances. While a belief’s semantic content is still partly dependent on one’s mental states, in at least some cases it is also dependent on one’s external environment. So, premise (1) is false; it’s possible to have the same NP properties but different semantic content and the outcome be different due to the external component of semantic content (and thus some other part of the world) be different. (Steven uses a different example involving treasure maps, but I prefer the classic Twin Earth scenario.)

The problem with this objection is that it largely misses the point. Suppose it’s true that in at least some cases, semantic has both an external and an internal (i.e. part of the mental state) component just as it does in the Twin Earth scenario. By “semantic content” in premise (1) I had in mind only that part of the semantic content that is part of one’s mental states, and if that semantic content could be literally anything at all without affecting behavior—even garbage beliefs—then we still get the same problem particularly when garbage mental states (akin to the mental states one has in dreams) vastly outnumber those that align with one’s external environment. I tried to explain to Spencer that by “semantic content” I had in mind only that part of the semantic content that is part of one’s mental state, but he apparently had some difficulty grasping the concept, so I switched the argument to be like this, replacing “semantic content” with “mental state.”
  1. (On naturalism) If a mental state’s associated NP properties had any different mental state associated with it instead, the same outcome in the physical world (e.g. one’s behavior) would result.
  2. If (1) is true, then mental states are causally irrelevant (on naturalism).
  3. Therefore (On naturalism), mental states are causally irrelevant.
Mental states include sense experience, memories, and the semantic content of beliefs (at least, that part of semantic content that is part of one’s mental state). This aspect of the debate largely inspired my article Mental States are Causally Irrelevant on Naturalism.

Plantinga’s Objective Probability



Spencer raised the objection that applies for theists who believe God is metaphysically necessary. On the sort of probability that Plantinga (the originator of the EAAN) normally uses which he’s called “objective probability” a claim being metaphysically impossible means it has a probability of zero. So for the theist who believes God is metaphysically necessary, naturalism is false in all possible worlds, which means N&E is false in all possible worlds, which (on the typical probability axioms) Pr(R|N&E) is undefined because it would mean dividing by zero. I agreed with Spencer that the theist who believes God is metaphysically necessary can’t reasonably affirm the Probability Thesis when using Plantinga’s type of objective probability.

But it’s not a very serious problem. First, this objection won’t help the naturalist all that much because on this objection the Pr(R|N&E) is undefined by God existing in all possible worlds, and if the naturalist is to concede that God exists in all possible worlds (including the actual one), the falsity of the Probability Thesis by this means is a very Cadmean victory for naturalism. Second, other types of probability are available. In the debate I used the fact that mathematics can give us a probabilistic primality test (the Miller-Rabin primality test in particular) and quantify a high probability (high but less than 100%) that a certain number is prime. Assuming math theorems give us objective truths, that probability is in a real sense objective, it’s probable in a way that’s independent of human opinion. But that sort of objective probability wouldn’t be Plantinga’s objective probability as he defined it, since on Plantinga’s sense of objective probability the objective probability of the number being prime is either 0% or 100% (a number is either prime in all possible worlds or composite in all possible worlds). We can call this type of probability, one of objective evidential support relations, as objective epistemic probability. It’s true when Plantinga originally introduced EAAN he was using his variety of objective probability, but he also claimed the argument can work with epistemic probability, and I agree; the justification I gave for the Probability Thesis does seem to work for objective epistemic probability.

I found it odd that Spencer seemed to think his objection posed a serious problem after how I explained why it wasn’t (e.g. 1:55:51 to 1:56:41). Spencer (in 1:56:19 to 1:56:41) was apparently unconvinced that my justification for the premises that argued for the Probability Thesis worked for epistemic probability, but was extremely vague about why anyone should doubt that such justification works for epistemic probability.

Supervenience Thesis



To illustrate what supervenience means, mental states supervening on brain states means that there cannot be a difference in mental states without there being a difference in brain states. On naturalism is true, I think it is very likely that mental states supervene on brain states due to some set of physical laws; i.e. that mental states supervene on brain states as a matter of physical necessity. What philosophers call strong supervenience is a supervenience relation that holds in all possible worlds; e.g. mental states strongly supervening on brain states means that there is no possible world where a different mental state is associated with the same brain state. The supervenience thesis (as Spencer used the term) claims that mental states strongly supervene on mental states. Even if I were a naturalist, I wouldn’t find the supervenience thesis plausible; electrochemical reactions generating a different mental state seems too easily conceivable to me, with no good reason (it seems to me) to think that the relationship couldn’t be different in any other possible world, any more than thinking that the physical laws themselves couldn’t have turned out differently.

Still, let’s leave that aside and suppose the supervenience thesis is true. Spencer claimed that the supervenience thesis, if true, would render premise (1) false of this argument (1:36:22):
  1. (On naturalism) if any different mental states were associated with the same physical conditions, the same outcome in the physical world (e.g. one’s behavior) would result.
  2. If (1) is true, then mental states are causally irrelevant (on naturalism).
  3. Therefore (on naturalism), mental states are causally irrelevant.
The context here is that we were discussing panpsychism (the view that all matter has some degree of consciousness—if that view sounds wacky to you, you’re not alone) and I was basically asking what would happen if we had all the same physical conditions including all the same laws but different mental states were associated with those conditions—would we on naturalism get the same outcome (1:33:58 to 1:34:40)? My answer: yes, of course we would, because we have the same initial conditions, same physical laws (by definition, physical laws correctly say what will occur given certain physical initial conditions in the absence of any supernatural intervention), and when naturalism is true there’s no supernatural intervention to change what would occur. Thus, premise (1) seems obviously true.

Spencer’s objection to premise (1) was the supervenience thesis.

The problem, as you might suspect, is that the truth or falsity of the supervenience thesis is irrelevant to the truth of premise (1). It’s not as if premise (1) is saying that it’s metaphysically possible for different mental states to be associated with the same physical conditions. It’s only saying that if different mental states were associated the same physical conditions, on naturalism we’d get the same outcome. Even if it were metaphysically impossible (somehow) for different mental states to be associated with the same physical conditions, it’s certainly conceivable that e.g. some different mental state be associated with the same brain state; there’s no self-contradiction there. And we can conceive of what would happen if, on naturalism, the same physical conditions had different mental states associated with them.

Note that while it is conceivable for different mental states to be associated with the same physical conditions on naturalism, it is not conceivable to get a different outcome on naturalism. Why? By definition, physical laws correctly say what will occur given certain physical initial conditions in the absence of any supernatural intervention. Since, as I specified in the thought experiment, we were dealing with the same physical laws, it would be logically contradictory to have naturalism be true and have the same physical conditions (including the same laws) and getting a different outcome. [3]

I had a difficult time getting Spencer to understand that the supervenience thesis is irrelevant. Fortunately, the Capturing Christianity moderator Cameron was (somehow) able to break through Spencer’s mental fog. If you want to see me struggle and fail while the moderator succeeds, see 1:33:58 to 1:42:04 of the debate.

Nonpropositional Evidence



Sometimes you know your beliefs to be true because they are justified on the evidential basis of other beliefs (e.g. facts presented in a criminal trial), and in that case you’re dealing with propositional evidence. Nonpropositional evidence is evidence that comes from something other than the inferential basis of other beliefs; e.g. the experience of being appeared to redly (roughly, “It seems to me that I’m having a sensation of redness”) justifies your belief that you are being appeared to redly. The experience of me remembering I had breakfast this morning justifies my belief that I had breakfast this morning. I don’t infer my memory from another belief; I just intuitively experience it. Spencer claimed nonpropositional evidence could save R from defeat (1:57:22), but was fuzzy on the details.

I anticipated that Spencer would bring up nonpropositional evidence in his closing statement, so in 1:54:40 I explain that N&E is like ingesting drug XX and that even if I get nonpropositional evidence for R sometime after ingesting the drug (whatever that might be—a strong feeling that R is true for me perhaps?), R is still defeated for me. I can very strongly feel that I have accurate mental states but as long as that happened long after I ingested drug XX (or the equivalent; e.g. the XX-mutation) I still have an undefeated defeater for my mental states aligning with how the external world is.

So I basically rebutted his point before he made it in his closing statement and he didn’t really respond to my rebuttal, nor did he give any details about what this nonpropositional evidence might be or how on earth it could save R from defeat. It seems very unlikely that there’s any viable way to save R from defeat here.

Conclusion



All things considered I think the debate went rather well for me. One weakness is that my rusty memory failed to recall what neutral monism is (he brought it up in the debate) through I did remember panpsychism as well as nearly every other philosophical tidbit he brought up, including having a more accurate memory of semantic epiphenomenalism. It was interesting how at one point he eventually agreed with me that the Defeater Thesis is true after the Capturing Christianity moderator explained it to him (1:16:15 to 1:21:55) then we went back to argue the Probability Thesis until he apparently couldn’t think of any good objection against my argument for it (1:52:03 to 1:53:00) and then disputed the Defeater Thesis (appealing to vague nonpropositional evidence)! For the most part, my position seemed to be on stronger intellectual ground and I had the means to justify both the Probability Thesis and Defeater Thesis fairly convincingly.

I was genuinely impressed with the moderator’s skills at moderating; in addition to keeping things on track, a couple times he was able to explain things to Spencer when I was unable to! The moderator was also good at trying to fight bias against his own side by giving my interlocutor the last word. If I ever have a debate on my own YouTube channel I’d want him as the moderator.



[2]Beilby, James (editor). Naturalism Defeated? (Ithaca, New York: Cornell University Press, 2002), p. 7-8.

[3] What would “outcome” mean in a naturalistic and truly random universe (where different states of affairs are possible with the same initial physical conditions)? Suppose the laws say that 50% of the time the resulting state of affairs will randomly be state of affairs S1 and the other 50% of the time the resulting state of affairs will randomly be state of affairs S2. In that case, the “outcome” is 50% of the time it will be S1 by chance, and 50% of the time it will be S2 by chance, and that outcome will not be rendered different by having a different mental state associated with the same conditions (by which I would mean the “on average” frequencies would not be rendered differently). In retrospect I perhaps should have used the word “consequences” rather than “outcomes.”

< Prev   |   1   |   |   3   |   Next >

Post-EAAN Debate Reflections (p. 2)

Post-EAAN Debate Reflections
 |   1   |   2   |   | 

The Defeater Thesis



To defend the Defeater Thesis I’ll use a number of scenarios that involve the fictional drug XX used in a scholarly paper titled A Mental States Approach to the Evolutionary Argument Against Naturalism. Drug XX renders one’s cognitive faculties unreliable within two hours for the vast majority of those who take it. The minority have a blocking gene that codes for a protein that blocks the effect of the drug. The XX-mutation a genetic mutation that injects drug XX into the bloodstream soon after one is born. The gist is basically that N&E is like ingesting drug XX when it comes to providing a defeater for R. I claim that R is defeated in each of the followings scenarios:

Scenario (1): I know that my friend Sam ingested drug XX and that twenty-four hours later he came to believe that that a series of tests has confirmed that he has the blocking gene and that his cognitive faculties are reliable, though I have no independent reason for thinking this occurred. And since Sam obtained his belief about the cognitive tests long after he ingested drug XX, there’s a reasonable chance that this belief was produced by unreliable cognitive faculties, and so this would-be evidence for Sam’s cognitive reliability (Sam’s memory of passing the cognitive tests) is undermined by drug XX, and my belief Drug XX entered Sam’s bloodstream defeats my belief that Sam’s cognitive faculties are reliable.

Scenario (2): I ingest drug XX and know of no relevant difference that distinguishes my case from Sam’s. Days later I come to believe I have taken a series of tests that say I have the blocking gene and that my cognitive faculties are reliable, but since this belief came long after I ingested drug XX, it seems this would-be evidence for my cognitive reliability (my memory of passing the cognitive tests) is undermined by drug XX, just as the would-be evidence for Sam’s cognitive reliability (Sam’s memory of passing the cognitive tests) is undermined by drug XX in (1). Thus my belief Drug XX entered my bloodstream defeats my belief that R is true with respect to me.

Scenario (S3): A doctor has injected me with drug XX soon after I was born, and I come to believe in the following. I am a renowned scientist who has built a machine that I know is capable of reliably detecting whether and when drug XX entered a person's bloodstream, and I am extremely confident about the reliability of this machine. I administer the test to myself and the machine reports that drug XX entered my bloodstream at around the time I was born; as such, I am as confident that drug XX entered my bloodstream as I am in scenario (2). Later I come to believe I have taken an extensive battery of cognitive reliability tests to confirm that I have the blocking gene, but since this belief came long after drug XX entered my bloodstream, it seems this would-be evidence for my cognitive reliability (my memory of passing the cognitive tests) is undermined by drug XX just as it is in scenario (2), and so it seems my belief Drug XX entered my bloodstream soon after I was born defeats my belief that R is true with respect to me.

Scenario (4): I come to believe in the following. The XX-mutation afflicts approximately one in a million individuals, with only a small percentage of those with the XX-mutation having the blocking gene. I have constructed a device similar to the one described in (3) except this device detects whether evolution gave someone the XX-mutation, and I am as confident in the reliability of this machine as I am with the one in (3). The machine reports that I have the XX-mutation and thus that drug XX entered my bloodstream soon after I was born. Later I come to believe that I’ve passed a series of cognitive tests to confirm that I have the blocking gene, but since I believe these tests happened long after drug XX entered my bloodstream, it seems that this would-be evidence for my cognitive reliability is undermined by drug XX just as it is in scenario (3). My belief Drug XX entered my bloodstream soon after I was born defeats R for me here just as it does in scenario (3). Similarly, my belief that I have the XX-mutation (since I believe this mutation injects drug XX into my bloodstream soon after I’m born) defeats my belief that R is true with respect to me.

Scenario (5): I come to believe in the following. Via a nifty combination of scientific and philosophical argumentation, it is proven beyond all reasonable doubt that naturalistic evolution entails that the XX-mutation is inevitably a part of any humanoid’s genetics. The aforementioned scientific and philosophical argumentation say that given N&E, it is likely that the XX-mutation rendered everyone’s cognitive faculties unreliable, though on N&E there is also the small chance that everyone evolved the blocking gene to render everyone immune to drug XX. N&E entailing that the XX-mutation is part of our genetics thus makes Pr(R|N&E) low, and I thus come to believe Pr(R|N&E) is low. I believe some time after it’s discovered that drug XX entered our bloodstream, credible scientists have run cognitive tests to confirm that we have the blocking gene. But since this belief came long after drug XX entered my bloodstream, it seems that, like scenario (4), this would-be evidence for my cognitive reliability is undermined by drug XX. My belief I have the XX-mutation defeats R for me here just as it does in scenario (4).

Scenario (6): The Probability Thesis is true and Pr(R|N&E) is low, but I do not initially believe this and instead think I am the product of a sort of evolution that makes my cognitive reliability very likely. Later however I study philosophy and see for myself that the probability of my humanoid cognitive faculties being reliable given that I am a product of naturalistic evolution is low. Afterwards I come to believe I have taken an extensive battery of tests that establish my cognitive reliability, but since this belief came long after naturalistic evolution created my cognitive faculties and I believe that given N&E, naturalistic evolution has a high probability of giving me unreliable cognitive faculties, it seems that this would-be evidence for my cognitive reliability is undermined by the effects of naturalistic evolution similar to how naturalistic evolution giving me the XX-mutation in scenario (5) undermines my would-be evidence for R, and so it seems that I have a defeater for my belief that my cognitive faculties are reliable.

Scenario (6) is of course just the scenario of the Defeater Thesis: Pr(R|N&E) is low defeating R (for the naturalist who accepts evolution). Summarizing the scenarios and their defeaters for R:
  1. Sam ingested drug XX defeats R for Sam.
  2. I ingested drug XX defeats R for me.
  3. Drug XX entered my bloodstream as an infant defeats R.
  4. I have the XX-mutation (but most don’t) defeats R.
  5. I have the XX-mutation (everyone has the mutation) defeats R.
  6. Pr(R|N&E) is low defeats R.
The reasoning for the Defeater Thesis is this:
  1. R is defeated in scenario (1).
  2. If R is defeated in scenario (1), R is defeated in scenario (2).
  3. If R is defeated in scenario (2), R is defeated in scenario (3).
  4. If R is defeated in scenario (3), R is defeated in scenario (4).
  5. If R is defeated in scenario (4), R is defeated in scenario (5).
  6. If R is defeated in scenario (5), R is defeated in scenario (6).
  7. Therefore, the Defeater Thesis is true.
The general idea is that there doesn’t seem to be any relevant difference between the two scenarios of any premise (2) through (5) above where R is defeated in one scenario but not defeated in the other. If that’s true, and R is defeated in scenario (1), then the Defeater Thesis is true.

< Prev   |   1   |   2   |   |