Shadows in the Cave

Here is a very small sample of a pervasive phenomenon in the dialogue. I have chosen it because it requires no philosophical background, and because it is probably the most familiar section in the dialogue.

The passage at the beginning of Book VII of Plato's Republic is so well-known that it may be worth actually reading it. Socrates is talking with Glauco (in Greek transliteration, Glaukon):

And do you see, I said, men passing along the wall carrying all sorts of vessels, and statues and figures of animals made of wood and stone and various materials, which appear over the wall? Some of them are talking, others silent.
You have shown me a strange image, and they are strange prisoners.
Like ourselves, I replied; and they see only their own shadows, or the shadows of one another, which the fire throws on the opposite wall of the cave?
True, he said; how could they see anything but the shadows if they were never allowed to move their heads?
And of the objects which are being carried in like manner they would only see the shadows?
Yes, he said.

Socrates presents an impossibility. On the very same wall opposite the prisoners are to be found a) the shadows of themselves, b) presumably the shadow of the wall, c) and the shadows of objects carried by men passing along the wall. Many attempts have been made to illustrate the analogy, and several shadowy versions are replicated in the Cave of the Internet.

In this version, the fire is located correctly behind and above the prisoners, explicitly stated by Socrates just a few lines earlier. The shadows of the prisoners are necessarily cast onto the ground before them, and not onto the wall. Thus, either the fire is not above and behind, or the shadows of the prisoners cannot be opposite them on the cave wall. There is something wrong with the account, and it should not be ignored. That it is ignored must be ascribed to an unthinking assumption that the account is somehow to be understood despite the discrepancies: small points in the general scheme of things may be ignored. The wall and the models cast no shadows whatsoever; they would have obliterated the shadows of the prisoners, and are therefore inconvenient.
The inconvenience may be solved in the following way:

These prisoners cast no shadows (onto the ground), not to mention the wall's apparent translucency. A more sophisticated illustration retaining the shadows of the prisoners and the shadows of the models is to be admired for its ingenuity and its more sophisticated perversion of the laws of physics:

Here at last we have both the shadows of the prisoners and the shadows of the models, thanks to some masterful bending of space. Even this, however, fails to meet the criteria of the account, where the prisoners are explicitly unable to remove their gaze from the wall directly in front of them; the shadows of themselves are expressly opposite them on the cave wall, exactly where the shadows of the models are also said to be.

To return to the passage quoted at the top of this entry. This is not Plato's account of a cave. This is not even Socrates' account. Socrates is asking Glauco whether he can imagine this cave, and it is Glauco who says that he does. Clearly Glauco does not imagine it, since it is impossible. No one is expected to accept this cave analogy at face value, except for people like Glauco.