Tolkien and the Monsters

[Fordim Hedgethistle]

To sum up, however, the point that I am trying to make is that, to my mind, evil requires some degree of choice. If a creature does not have that choice, can it truly be evil? And doesn't this question go to the very heart of the nature of evil in Middle-earth?

Couldn't agree with you more. But I think we can refine that by saying that evil is defined not just by any choice (i.e. an 'evil' choice) but by choosing to seek or take up "evil knowledge."

As to the whole Shelob v Sauron evil thing, it can be answered in two ways. First, the way you would appear to be answering it: Shelob is not truly evil, just doing her thing (that is, she is not Sauron-evil, which is real evil).

The other way to answer it is the way I prefer: she is evil but in a different way than Sauron is evil. Sauron does evil for the sake of the evil knowledge that he seeks/wants in his desire to overthrow the created world; Shelob is evil because of her desire to consume the created world. So closely allied, but not quite the same thing. The common element, I suppose, would be that they each put the fulfilment of their individual desires ahead of creation.

As to Shelob-Maiar: I admit, I don't really know this for a 'fact': but she sure isn't just some overgrown spider either!