The new evil demon problem at 40

Abstract

1 THE NEW EVIL DEMON PROBLEM

I shall use ‘epistemic warrant’ and ‘epistemic justification’ interchangeably for a normative property that provides a good route to true belief and knowledge.1

Here are two facts:

• FACT ONE: Beliefs based on taking perceptual experiences at face value are defeasibly epistemically warranted.
• FACT TWO: Defeasibly taking perceptual experience at face value is a reliable route to true belief.

Epistemologists disagree over their relationship.

Reliabilists believe the second helps explain the first. And by “explain” the reliabilist sets out to really, genuinely explain, to “state conditions that clarifies the underlying source of justificational status,…conditions [that are] appropriately deep or revelatory,” not simply conditions that state “correct” necessary and sufficient conditions (Goldman, 1979: 1–2, emphasis added). Reliabilists then hold that “good” psychological processes—good mind-to-mind transitions, such as forming perceptual beliefs based on perceptual experiences—are epistemically correct because they are reliable routes to truth.2 Hence the motivation for simple reliabilism:

In all possible worlds W, a belief is prima facie epistemically warranted in W if and only if (to the extent that) the psychological processes that caused or sustained the belief reliably produces true beliefs in W.

So-called “internalists” disagree. They deny that being a reliable route to truth is necessary for warrant, relying on the “New Evil Demon” scenario to make their case.3 Here's the standard version:4

Norma is an ordinary human adult, with normally functioning perceptual and cognitive capacities, in her normal environment. Walking around the park, she forms reliably true perceptual beliefs about her environment. Perception, in her world, is a reliable route to truth and knowledge.

Vicki is Norma's psychological duplicate in another possible world. From the inside, as it were, everything looks exactly to Vicki as it does to Norma. But Vicki is not walking around a park. Instead, she is floating in a vat of nutrients, where her sensory systems are hooked up to a massive super-computer. The computer deceives Vicki by inducing type identical perceptual representations to Norma's. That's why everything (in perception) looks the same to Vicki as it does to Norma, but nothing in Vicki's immediate surrounds is as it seems. Vicki, unaware of and unable to detect the deception, forms massively false perceptual beliefs. Perception, in her world, is not a reliable route to truth and knowledge.

Internalists conclude that Vicki's perceptual beliefs, though massively in error, are nonetheless just as justified— “equally justified”—as Norma's. Taking perceptual experience at face value, given no reason to suppose it is not a good guide to truth in the circumstances, is just what Vicki is supposed to do. That's the correct or proper response to her perceptual experiences. If Vicki's perceptual states justify her perceptual beliefs, simple reliabilism doesn't stand a chance. That's why it's called the New Evil Demon Problem.

Internalists John Pollock and Joseph Cruz, citing the demon world case, conclude that:

[R]eliability has nothing to do with epistemic justification… [B]eliefs are justified because the believer is “reasoning correctly” (in a broad sense of “reasoning” [where perceptual experience are reasons in an extended sense and so perceptual belief formation is a kind of reasoning]). If one makes all the right epistemic moves, then one is justified regardless of whether the belief is false, or nature conspires to make such reasoning unreliable. (Pollock and Cruz, 1999: 113–114).

If justification strongly supervenes on an individual's (nonfactive) mental states and relations, as the internalist supposes, but the reliability of perceptual beliefs is a contingent matter of fact, then justification as such has nothing to do with reliability or truth. Since our first fact is necessarily true, says the internalist, the second fact is irrelevant to epistemic justification. That's the moral, according to the internalist, of the New Evil Demon Problem. No wonder so many internalists so easily dismiss reliabilism with a one-liner.

We owe the New Evil Demon Problem to Stewart Cohen. Cohen discovered the problem while a graduate student at the University of Arizona, at one time the center of the epistemological universe. Cohen first published the problem in a paper co-authored with Keith Lehrer in 1983 (Lehrer and Cohen, 1983) and then developed it further in his landmark paper “Justification and Truth” (Cohen, 1984; cf. Pollock, 1984; Foley, 1987). The New Evil Demon Problem is now over forty years old.

Reliabilists remain undeterred. Here are two ways reliabilists have responded.

I call the first, following Ernest Sosa (2003), the “heroic” response. According to the heroic response, internalists are just mistaken that Vicki has justified beliefs. This response starts with the force, role, or job of epistemic warrant: to be a good route to truth and knowledge. That's what makes epistemic justification epistemic. Justification as such then strongly supervenes on the reliability of the belief-forming process. But since perception is only contingently reliable (as the demon world case vividly illustrates), perceptual justification does not strongly supervene on an individual's (non-factive) mental states and their relations. Internalists, the idea goes, simply misunderstand the role or force of epistemic justification. Vicki's perceptual beliefs are then obviously not justified, for they don't stand a chance of being true. Philosophers taking this line include Sanford Goldberg (2012a),5 Thomas Senor (2013), and Jack Lyons (2013).6 I shall call these three philosophers, and their like-minded colleagues, “our heroes.”

Our heroes, though they deny that Vicki's beliefs are epistemically justified, usually grant that she is being rational in so believing, that her perceptual beliefs are rationally held (Meyers, 1988; Lyons, 2013). That, they think, often explains the internalist's “intuition” that Vicki's perceptual beliefs are just as “justified” as Norma's, for so many internalists tend to use ‘justification’ and ‘rationality’ interchangeably (e.g. Cohen, 1984: 283; Foley, 1987; Huemer, 2001: 19; Smithies, 2012: 274; Wedgwood, 2012: 280; Dogramaci, 2015: 777; cf. Siscoe, 2021; Sylvan, ms.). But once we separate epistemic justification (in the sense of a good route to truth and knowledge) from structural rationality, we should not be so quick to judge that Vicki's beliefs are epistemically justified.7

That's the first response. I call the second the “special-circumstances” response. According to this response, Vicki's beliefs are epistemically justified, even though her perceptual representations are not de facto—“in situ”—reliable. They are epistemically justified because her perceptual representations (her perceptual belief-forming processes) are reliable in a special set of circumstances. It's because they are reliable in special circumstances, the idea goes, that they continue to contribute to the epistemic warrant for perceptual beliefs even when the individual is not in special circumstances. Because Vicki's perceptual belief-forming processes are reliable in special circumstances, the idea goes, they produce epistemically justified beliefs even while Vicki is floating motionless and massively deceived in a vat of nutrients.

I shall spend most of the paper on this response. For this response to work, it must at least specify “correct” necessary and sufficient conditions for epistemic justification. But it must also specify conditions that are appropriately deep or revelatory. In other words, this response must not only correctly predict that Vicki's perceptual beliefs are justified, but it must also explain why that should be so.

Three of the most influential philosophers of the last fifty-years—Alvin Goldman, Ernest Sosa, and Tyler Burge—have all pursued versions of the special-circumstances response. It's the party line. In the first half of the paper, I will criticize their respective versions of this response. In the second half I will develop my own. The point of the second part is to develop the most plausible reliabilist account of warranted beliefs in demon world scenarios. I shall return to our heroes when concluding.