Internalism and the Human Condition by Jimmy Stephens

The properties of human nature are irreconcilable with internalism. Human nature, at present, has the following properties: finitude, fallibility, and foulness.
Finitude refers to the limited nature of the human mind. We do not know all facts; we are not omniscient. We know little about what is going on beyond the gestalt provided by our five senses. We cannot know everything that is going on around the globe. We know comparatively little about what is going on in the universe in total. We know relatively little about the past, especially prehistory. We know nothing about the future except scarce predictions. But in all of these things, we are dependent on our environment.
Whatever we could know a priori is neither practically brought into our sense-experience so that we can guarantee historical events, for example, nor are historical events deductible from an innate a prior.
All this is just to give a rough sketch to say: we don’t have an infinite, all-encompassing idea of the universe. We cannot know all facts in reality. We cannot explain any fact of reality in relation to all other facts.

So then, we have no guarantee that our present conception of the universe isn’t inherently flawed. Perhaps, somewhere out in the unknown, somewhere on the timeline of philosophy, someone will discover something that disproves our most basic concept of the universe. Worse, since we cannot know all facts, perhaps there is a fact that entails all of our pretenses of knowledge to be delusional folly.
Fallibility is obvious. Human beings make mistakes, sometimes on a nuclear scale. The best internalism could offer, therefore, is wholesale fallibilism. Since wholesale fallibilism is incoherent, internalism is likewise impossible.

Foulness refers to the sinful nature of humanity. We are not immaculate, we are immoral. We lie, cheat, and steal. Sometimes we deceive ourselves. People have unconsciously deceived themselves before and some have willfully accomplished delusion.

Since, on internalism, all knowledge depends for justification on the knower, all justification could amount to deception, unconscious or willful. The former could just be a case of insanity – perhaps everyone is just a delusional animal.
And for the internalist, we need not bicker with him over petty details in the universe. All that matters, for the sake of his view, is that he cannot compete with God in terms of attributes. Without infinity, the internalist has no way of guaranteeing the shape of the universe is not an inherently Christocentric one. Without infallibility, the internalist cannot guarantee that he isn’t borrowing from the Christian worldview, cannot guarantee his own autonomy. Without sinlessness, the internalist cannot answer Romans 1.