I see the answer as being "metaphor".

I hear that's correct.

Back, coupla centuries ago, people were under the impression that the eyes emanated light and that's how we could see (reality/the truth as it were). It's just this misconception that's carried over to the present. Truth is you don't see (anything), you..er...

So for example, when one says "I see that violence is bad", "I see your comments are fair". — KantDane21

Interestingly, Greek had at least three different words that we now translate into English as ‘to see’. Blepo refers to physically looking or noticing with our eyes. Theoreo refers to observing, and includes thinking and deciphering what the visual cues might mean (not necessarily correctly). Horao refers to seeing with the mind, understanding mentally or spiritually.

I think I've got a feel for what you mean.

So for example, when one says "I see that violence is bad", "I see your comments are fair". — KantDane21

I don't think it's a figure of speech at all. It's just one of the usages allowed by the definition of the word "see." From Merriam Webster:

transitive verb
1a: to perceive by the eye
b: to perceive or detect as if by sight
2a: to be aware of : RECOGNIZE
sees only our faults
b: to imagine as a possibility : SUPPOSE
couldn't see him as a crook
c: to form a mental picture of : VISUALIZE
can still see her as she was years ago
d: to perceive the meaning or importance of : UNDERSTAND — Merriam-Webster

I think etymologically we use senses to convey knowledge in general just as a biological derivative. We rely on our senses a lot. If it's prevalent in attic greek/sumerian I wouldn't be surprised but we had a huge empiricist turn in the early modern era which was separate of the catholic aristotelian turn where everything is from God.
There are several possible derivations.

I don't think it's a figure of speech at all. It's just one of the usages allowed by the definition of the word "see." — T Clark

I think it's a deadaphor.

I think it's a conceptual metaphor. Another example is talking of time in terms of space: move the meeting forward to next week. In calling these conceptual, the claim is that this is not only how we talk--a set of convenient outward expressions--but also how we think.

The most famous theorist of this stuff is George Lakoff, who (with Mark Johnson) wrote Metaphors We Live By.

Here's a paper by Lakoff and Johnson (PDF): Conceptual Metaphor in Everyday Language. It gives an idea of how deeply metaphorical our language (and our thinking) is.

"I see" said the blind carpenter as he picked up his hammer and saw. He lied, because he didn't see at all." An old idiom. My grandmother used to say this to me when I was a child (for no apparent reason). I'm 75.

"To see" is the infinitive form of the verb"see" which derives from ancient roots in the Indo-European language. "Old English sēon, of Germanic origin; related to Dutch zien and German sehen, perhaps from an Indo-European root shared by Latin sequi ‘follow’.

'Cat's pajamas' is a figure of speech.

'Cat's pajamas' is a figure of speech. — Bitter Crank

I've just realized that "the cat's pyjamas" means the same as "the dog's bollocks".

Here's a paper by Lakoff and Johnson (PDF): Conceptual Metaphor in Everyday Language. It gives an idea of how deeply metaphorical our language (and our thinking) is. — jamalrob

I see where you are coming from.

Language as metaphor
Nietzsche wrote “We believe that when we speak of trees, colours, snows, and flowers, we have knowledge of the things themselves, and yet we possess only metaphors of things which in no way correspond to the original entities.”

Metaphor is language’s most powerful weapon.

Consider "I can see the solution" and "I can see the apple". We commonly assume that "I see" is used metaphorically in the first instance and literally in the second instance, however language is more complex than this.

We talk all the time with metaphors but do not notice this because we use them naturally, both in daily life and in science - Maxwell’s demon, Schrödinger's cat, Einstein’s twins, the Greenhouse Effect, natural selection, dendritic branches. Metaphors are not paraphrases for other literal expressions, but are how ideas are expressed. Metaphors describe the world and are not explanations.

Metaphors and Indirect Realism
The conceptual metaphor, understanding one idea in terms of another, is foundational to the meaning of Indirect Realism.

Indirect Realism is the belief that our conscious experience is not of the real world itself but of an internal representation of the real world

As "the solution" is not an object in the world but a concept in the mind - "the apple" is also not an object in the world but a concept in the mind. Therefore, as we treat "I see the solution" as a metaphor, we should also treat "I see the apple" as a metaphor rather than literally.

A belief in Indirect Realism leads to a belief that not just is metaphor important in language, but "language is metaphor".

However, even the insight that our language is deeply metaphorical will not lead, as Lakoff and Johnson write, to any new perspective about "the truth", as "understanding one kind of experience in terms of another kind of experience" will always lead to an infinite regression, where "the truth" will always remain, as I see it, out of reach.