Grond said:
Unlike
Feanor,
Fingolfin's motives were not tainted with
evil. The "cause" may be just (in Feanor's case) but the motives were flawed/marred/influenced by evil.
How do we know what influenced Fingolfin's motives? Look at the evidence:
"Ever
Melkor found some ears that would heed him, and some tongues that would enlarge what they had heard; and his lies passed from friend to friend, as secrets of which the knowledge proves the teller wise. . .
many of the
Noldor believed, or half believed, the evil words. . . High princes were Feanor
and Fingolfin. . . but now they grew proud and jealous each of his rights and his possessions. . . to Fingolfin and
Finarfin it was said: 'Beware! Small love has the proud son of Miriel ever had for the children of Indis. Now he has become great, and he has his father in his hand. It will not be long before he drives you forth from Tuna!'" ~Of
the Silmarils and the Unrest of the Noldor, emphasis added
Take special note of the last two passages quoted- Fingolfins words in
Finwe's council show that he was just as deceived as Feanor- for Feanor would never have taken the authority or throne of his father (or in any way demeaned him) while Finwe lived, just as Fingolfin was not have conspired to displant Finwe.
I believe that Fingolfin's pledge to follow and obey Feanor was a recognition of his own fault in believing the lies of
Morgoth.
Remember too that Feanor was specifically targeted by Morgoth because he wanted Feanor's
Silmarils. The result was Finwe's death (which is an incredibly important aspect that lended itself to Fenor's Oath), and the loss of the Silmarils:
items 1 and 2 in Feanor's love. Thus, if Fingolfin had been the greatest among the Noldor, if he had created those jewels,
he would have fallen, just like Feanor.
That doesn't mean that Feanor's actions were without guilt, just don't think that Fingolfin was all high and pure- he just got less of Morgoth's attention. Of the three brothers Finarfin is least worthy of blame (though it's possible that he too was deceived by Morgoth), because he repented and returned to await the judgement of the
Valar.