Saturday, February 17, 2018

Post-EAAN Debate Reflections (p. 3)

Post-EAAN Debate Reflections
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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 H 2O 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).

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 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 an naturalistic indeterministic 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 be state of affairs S1 and the other 50% of the time the resulting state of affairs will be state of affairs S2. In that case, the “outcome” is 50% of the time it will be S1, and 50% of the time it will be S2 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.”

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Post-EAAN Debate Reflections

Home > Philosophy > Metaphysics

Post-EAAN Debate Reflections
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Overall I think the Evolutionary Argument Against Naturalism (EAAN) debate went very well. First, a recap of how I argued the EAAN.

EAAN Recap



To define some terms and abbreviations, a defeater is (roughly) a belief that undercuts the justification for another belief. To illustrate, suppose I see what seems to be a barn from twenty meters away and I form the belief That’s a fine barn but later I believe a local when she tells me that a bunch of barn facades were in the area along with real ones. My belief There were barn facades in the area defeats my belief that I’d seen a barn. Naturalism is the view that the supernatural does not exist. Some abbreviations:

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


In other words, Pr(R|N&E) refers to the probability that our cognitive faculties are reliable given naturalism and evolution, where by “cognitive faculties” the EAAN is referring to those faculties that process or produce beliefs—such as memory, perception, and reasoning. In a nutshell, the evolutionary argument against naturalism goes like this:
  1. Pr(R|N&E) is low
  2. The person who believes N&E (naturalism and evolution) and sees that Pr(R|N&E) is low has a defeater for R.
  3. Anyone who has a defeater for R has a defeater for pretty much any other belief she has, including (if she believed it) N&E.
  4. If one who accepts N&E gets a defeater for N&E in the manner described in lines (1) through (3), N&E is self-defeating and can’t be rationally accepted.
  5. Conclusion: N&E can’t be rationally accepted (at least, not for the N&E believer who accepts premise (1)). [1]
Call premise (1) the Probability Thesis and premise (2) the Defeater Thesis. Denying the truth of evolution isn’t much of an option for the naturalist, so if the above evolutionary argument against naturalism is sound, the naturalist is in serious trouble.

Probability Thesis



Beliefs have semantic content (e.g. the belief that Snow is white and the belief that Two plus two equal four) and are associated with neurophysiological (NP) properties. If naturalism is true, the semantic content of a belief is causally irrelevant in the sense that it doesn’t matter which semantic content is associated with the NP properties; the same outcome in the physical world (e.g. one’s behavior) would result. A deductive 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.
Justification for (1): different semantic content associated with the same NP properties means the same physical brain state, so barring any supernatural intervention the same outcome in the physical world (e.g. one’s behavior) would result.

Justification for (2): True by definition; by “semantic content being causally irrelevant” I just mean it doesn’t matter which semantic content is associated with the NP properties; we’d get the same physical outcome.

So why would it matter if N&E entails that the semantic content of our beliefs is causally irrelevant? To avoid bias against our own species, think not of us but of alien creatures whose physiology is radically unlike our own, and let RA represent “The cognitive faculties of the aliens are reliable.” N&E is true for these aliens, thus making the semantic content of their beliefs causally irrelevant. Then on N&E the electrochemical reactions that cause the behavior of these aliens could generate any semantic content at all (e.g. 2 + 2 = 1 or Grass is air) without that content affecting behavior. The semantic content could even be “garbage” beliefs unrelated to the external environment, as in dreams, and it still wouldn’t affect behavior.

To illustrate the potential problem this creates, suppose a random belief is assigned for the answer to “What does two plus two equal?” Answers of one, two, rock, and sunshine would all be wrong. Randomly selected beliefs about the color of the sky and one’s age are similarly likely to be wrong. The enormous variety of garbage belief sets akin to dreams vastly outnumber those belief sets that accurately resemble one’s external reality. Since semantic content would be a causally irrelevant and useless byproduct of the biological processes, while it is still possible for the electrochemical reactions that produce advantageous behavior to also produce a reliably true belief set (as opposed to a garbage, dream-like one), it would be a very serendipitous coincidence indeed if the NP properties of our aliens also generate reliably true beliefs given _just_ N&E. We thus have the following deductive argument, with RA representing “the cognitive faculties of the aliens are reliable.”
  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).
Justification for (1): What’s true for the 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. Semantic content is a causally irrelevant and useless byproduct of the evolutionary process.
  2. Garbage belief sets 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 belief set instead of one the far more numerous garbage belief sets.
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 belief sets being far more numerous) than reliable ones.

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[1] Plantinga, Alvin. Where the Conflict Really Lies (New York, New York: Oxford University Press, 2011), p. 344-345. Though I worded it slightly and I added the “pretty much” part to avoid possible controversies that things like cogito ergo sum and I am being appeared to redly might create, since by my lights the fact that there might be a few exceptions like this don’t affect the heart of the argument.

Post-EAAN Debate Reflections (p. 2)

Post-EAAN Debate Reflections
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The Defeater Thesis



To defend the Defeater Thesis I’ll use a number of scenarios that involve the fictional drug XX. 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.

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