Between the mind and any external world are the five senses. The mind only knows what passes through these five senses. Therefore, for the Indirect Realist, anything we think we know about any external world comes indirectly from “inference to the best explanation”. However, for the Direct Realist, we are able to transcend these five senses and directly know about any external world.
One question for believers in SDR is how they explain their judgements are able to transcend their phenomenal experiences — RussellA
I can only speak for myself on this, but I do
not reject the idea that knowledge is mediated by the senses. What I reject is the idea that sensory content forms an epistemic base from which the rest of our knowledge about the world is inferred.
The key issue here is that sensation is
not a normative act. This means it is not conceptual and is not truth-apt – it is simply not the kind of thing from which the rest of our knowledge could be inferred.
By contrast, judgment
is conceptual and truth-apt. The act of judgment is part of the norm-governed process of inquiry. So, while judgments are
constrained by sensory content, they are not
inferred from sensory content. As we argued above, this would be impossible.
When we make perceptual judgments we are
not making judgments about sensory content. We are making judgments about things in the world (“there is a ship”). That’s not to say that we
can’t make judgments about sensory content – we can (“I am seeing red”) – but this is not what we ordinarily mean by the word “perception”. Instead, this is a reflexive, second-order kind of judgment more commonly referred to as “introspection”.
I would argue that perceptual judgments are neither inferred from nor justified by introspective judgments. If someone questions one of our perceptual judgments, we don’t try to justify it by appealing to introspective judgments. Instead, we appeal to background knowledge and other perceptual judgments.
Consider the example of John and Jane that
provided. Jane makes a perceptual
judgment (“the screen is orange”) and infers that the wavelength of the light is between 590nm and 620nm. Appealing to an introspective judgment (“I am seeing orange”) in order to justify her perceptual judgment simply won’t convince anyone, including herself. If she really wants to justify her judgment that the screen is orange, she’ll need to appeal to her background knowledge (optics, screens, color-blindness, etc.) and further perceptual judgments about her environment (current lighting, viewing angle, screen filters, etc.).
So when you ask how judgments are able to “transcend” phenomenal experience, my answer is that they can’t – at least not in the sense of bypassing or overriding the senses, nor by inference from inner representations. Rather, judgments were never justified by phenomenal experience to begin with. Sensory experience constrsins inquiry by supplying data, but epistemic authority belongs to judgment, which is governed by norms of sufficiency, relevance, and answerability to how things actually are. Once that distinction is in view, the need to “bridge” phenomenal experience via IBE largely dissolves.