But aside from this, we could complicate matters even further, for if we say Melkor and Sauron were creations of Eru, and if we on top of this argue that 'choice' is heavily if not entirely influenced by the base make-up/traits of an individual, then Melkor and Sauron both may never really had
a choice. An individual, whether we take it as a product of nature and/or nurter, finds it motivations either due to its 'genetic' make-up, and/or due to influences during its up-bringing and continuing existence (or can there be anything else involved?) If for example someone lacks activity in regions of the brain responsible for emotions, they might due to this will find themselves unable to feel with others. Is this a choice? No, it is a clear physical inability and could only be 'corrected' via surgical interferance (which currently as far as I am aware, medicine is not able to do yet). If your legs are paralized, you can not walk. It is not a matter of choice, it is a matter of your legs not functioning.
If you have found yourself on the end of betrayal repeatedly in your existence, you will more than likely become very cautious, if not even paranoid. Even someone who has not been betrayed will just look at the experiences of others and (if he or she is what we class as 'sane') rather not hand 1 million $s to a stranger on the street, to hold on to it for a few hours while going to the dentist. Do they in theory have the 'choice' to do so? Yes, but choice in practice, or 'acting' in a real life scenary, is majorly pre-influenced, and as such could be argued a rethoric illusion.
If we'd take a real good psycologist, and would be able to give them our whole existence to analyse, I am pretty certain they'd be able to predict our actions almost 100%. There are behaviour patterns to draw from (to maybe conclude some base traits due to genetics) and influences/experiences which would enable them to tell you exactly why you think what you think, and do what you do. Viewed like this 'true choice' becomes very debatable, and indeed, is very much debated.
Now taking all this, Melkor and Sauron possibly were created in ways that never allowed them to 'care' for the races of middle earth in the way Gandalf for example seems to do. Radagst on the other hand may was created to care for the 'animal' species on Arda and its plants (and btw.. Saruman is described as regarding Radagst a fool, probably for that, but Saruman also turned to what has been described 'evil'...)
Choice/free will in its own right is a subject of debate, it is not clear cut, and if we should lean to that choice in truth is an illusion, that than opens the can of worms whether an individual which has no choice but to act as he or she does, due to forms of pre-determination, can be classed 'evil' at all. Melkor was created by Eru in a way which one could argue did set him up for exactly the path he took, and the same could be argued for Sauron, and if so, would Eru than actually be the true evil one?
I'd say to the latter that we very possibly just can not understand the mind of a God (so one exists). If Eru would not be a fictional invention, but a defecto part of the creation of the universe (and Arda maybe another planet or some earth history wiped from our memory in all its traces but the mind of one man, namely Tolkien), then I'd sigh heavily and say I have no idea why Eru created Melkor in that way, whether it was a 'mistake' or planned, whether all that has happened and is still happening involves reasons simply beyond my knowledge and maybe even ability to comprehend.
But anyway, this all just underlines again the troubles we can run into when defining 'evil', for if we define it as a matter of 'choice', then we are ignoring the fact that 'choice' is still very much up for debate as well, and we are basing our definition on not yet overall agreed solid grounds. We can at best, in my view, say we 'believe' it to be this or that way, that 'our opinion' leans to one thing over another, but we can not claim absolutes, or at least I feel we should not, and as such I will
not claim that I know
what is correct, as there is enough debate to keep doubt and ponderings going, for me at least, and I am not alone with this, whether within the scientific nor philosophical community.
Do I however have 'tendencies' and 'likes/dislikes'? Yes I do, and I will for myself come to judgements about 'evil' in actions, but when it comes to judging an individual as 'evil' for their actions, I find myself troubled by many dilemmas...