Ryan Hedrich has written a post that's in part a taxonomy of Scripturalist positions, as well as interacting with my analysis:
Before engaging his post, I'll begin with some definitions:
Traditionally, knowledge was defined as true belief. However, that's inadequate inasmuch as we might accidentally entertain a true belief. So more recent epistemologists think some additional condition must be met for a belief to qualify as knowledge.
Some epistemologists think that if your belief is caused by a reliable process–a process that produces true beliefs, then that suffices to qualify as knowledge.
Other epistemologists think a belief must be "justified." On one view, a belief is justified if you have introspective access to sufficient reasons for your belief.
ii) Cartesian deceiver:
An agent or process that induces delusional beliefs in the human subject. It could be "God"–albeit a mischievous or malicious "God." It could be a creature or process from God that has the same deceptive effect.
It needn't be omniscient or omnipotent. A fallible deceiver could be the source of fallible beliefs, if our beliefs are dependent on that erratic source.
iii) Although the Cartesian deceiver is a thought-experiment, it has real-world analogues. LSD, brain cancer, brainwashing, and Alzheimer's can all produce delusive beliefs. Likewise, it's been argued that naturalistic evolutionary psychology is a Cartesian deceiver.
iv) In my experience, Scripturalists typically say there are two kinds of beliefs: unjustified opinion and knowledge. I'm not imputing that position to Ryan, who's more astute.
In my experience, Scripturalists typically stipulate that for a belief to count as knowledge, it must be infallible, incorrigible, or irrefragable.
v) The Cartesian deceiver poses a distinctive problem for Scripturalism–although Ryan's modified epistemology may avoid it.
I'm not suggesting that non-Scripturalists have a master key that enables them to unlock the trap. In one respect, Scripturalists, externalists, evidentialists, empiricists, Van Tilians et al. all fall prey to the Cartesian deceiver.
The question is how seriously you take it. Most epistemologists and Christian philosophers don't think that our ability to falsify the Cartesian deceiver should be a condition of knowledge. If we are unable to disprove the hypothetical Cartesian deceiver, that's not a good reason to doubt our beliefs. That doesn't cast reasonable doubt on our beliefs. Indeed, it would be unwarranted to take that thought-experiment too seriously.
vi) However, Scripturalism sets the bar so high for knowledge that unless it can disprove the Cartesian deceiver, almost nothing will count as knowledge. That's what makes it a distinctive problem of Scripturalism.
Take internalism. Suppose you have introspective access to your reasons. They seem to be good reasons. But how is that a check against self-delusion? Like LSD, the Cartesian deceiver is persuading you to mistake bad reasons for good reasons. You can't help but find these reasons to be convincing, even though they are deceptive reasons.
vii) Scripturalists who deny self-knowledge are thereby implicated in a position that's even more skeptical that Descartes. He at least allowed for self-knowledge ("Cogito, ergo sum"). And from that solipsistic starting-point, it's possible to invoke some theistic proofs. That takes you beyond solipsism. But Scripturalists who deny self-knowledge can't even get that far.
viii) Let's consider Ryan's classifications:
"Subscribe to a purely externalist view on which, say, divine occasionalism or illumination infallibly causes true beliefs, though from a first person perspective we can't know when this occurs."
But that's impotent against the Cartesian deceiver objection, for it uses occasionalism or illumination to infallibly cause false beliefs. The Cartesian deceiver is the source of the delusive illumination or primary caused delusions.
"Scripturalist: The Bible isn't ink marks on a page. It's the meaning of the physical text, if there even is a physical text."
Once again, that's impotent against the Cartesian deceiver objection. What if the Bible or the "word of God" I perceive is just a hallucination? A Matrix-like simulation that bears no resemblance to the real word of God?
The Cartesian demon is the news feed, planting false memories. What I take to be the "word of God" is whatever the Cartesian deceiver input directly into my mind.
"Sensations are neither true nor false and so cannot function as premises by which our beliefs are inferentially justified."
I think that's too crude or overstated. There are different kinds of sensory information. The sound of breakers isn't true or false. But the spoken word (a sentence) can be true or false.
a) The spoken word is structured sensation that uses sound waves to encode and communicate ideas or propositions.
b) Likewise, although sensations alone are neither true nor false, sensory input, in combination with ideas, can generate true or false beliefs.
If I see a red rose, I can rightly infer that I saw a colored object. If every red object is a colored object, then that's a valid deduction.
Now, it may not be possible to derive the principle that every red object is a colored object from sensory perception or induction. That principle may be intuitive or innate. That must already be in mind for me to draw inferences about the rose. But seeing the rose, in combination with that a priori truism or analytical truth, yields a new and true belief. As one philosopher notes:
I have stated the basic claims of rationalism and empiricism so that each is relative to a particular subject area. Rationalism and empiricism, so relativized, need not conflict. We can be rationalists in mathematics or a particular area of mathematics and empiricists in all or some of the physical sciences. Rationalism and empiricism only conflict when formulated to cover the same subject.
c) Likewise, seeing one albino crow is enough to disprove the universal negative that all crows are black.
"Steve said he believed that some beliefs are infallible. I'm not sure that he meant this in the context of internally justified beliefs."
I meant it in a conditional sense: If we define an infallible belief as a true belief that could not be mistaken, and if God predestines all beliefs (including the subset of true beliefs), then there's a sense in which all true beliefs are infallible, inasmuch as they could not be other than what God foreordained.
But that's conditional: given predestination. If someone raises the Cartesian deceiver objection, I may not be able to disprove that objection. Mind you, I don't think that's a debilitating concession. It's just a thought-experiment.
But because Scripturalism sets the bar higher than I do for knowledge, what works for me won't work for Scripturalism.
"Our senses can cause numerous false beliefs. Sense knowledge is fallible."
True, but the same can be said for reason and memory. Scripturalists need to get down from their high horse and join the rest of us at ground level. They stipulate an inhumane standard of knowledge. Finite creatures can't satisfy those godlike conditions. But why should we?