Do you agree that "Fate is stronger/... Than any man's mind"? Why or why not?
Ultimately, the answer to this question outside of the context of this poem is for each individual to decide; within the context of the poem, however, the answer to the question is relatively straightforward. The Seafarer falls into a category of Anglo-Saxon poetry known as the elegies, all of which are concerned with the struggles of an outsider and with the vicissitudes of fate (compare The Wanderer and The Ruin). Anglo-Saxon poetry maintains that 'wyrd bith ful araeth' (The Wanderer)--that is: fate is fully inexorable. This is an idea rooted in pre-Christian Anglo-Saxon culture, and which continues into later poetry set within a Christian context. The idea of 'wyrd', or fate, as something man is unable to defend himself against, prevails within The Seafarer.
There is a semantic field of being bound, shackled and fettered which can be found in lines 8-11 of this poem: the seafarer is 'fettered' by the whims of the sea and of fate. His free will is not enough for him to break these shackles. The seafarer, like the narrator of The Wanderer, is far from his kinsmen, but there is no question of his returning to them, even though 'the wish of [his] heart' is to do so (line 36a). The seafarer tells of his woes at being exiled for the larger part of the poem, before coming to express the certainty of all men that they will eventually die, whatever they may choose for themselves. The only thing they can choose is to place their faith in their Lord (possibly, but not necessarily, the Christian god in the original context) in order that they will live on beyond this life (lines 88 - 104).
Some scholars believe that line 116 is the original end of the poem: 'Fate is greater and God is mightier than any man's thought.' (What follows is a section about the joys of heaven that is possibly a later Christian addition to the original poem.) Whether or not this line is the poem's conclusion, it is certainly its overriding preoccupation: fate, for the Anglo-Saxon exile, is most certainly more powerful than man.
In this poem the seafarer does determine that "Fate" is stronger than man's mind. The answer to this question depends upon the definition of "Fate." In the poem, and especially in a Christian reading, "Fate" is synonymous with God's will. So, if we take Fate to mean the result of God's divine plan, then it makes sense (within this reading of the poem) that Fate/God is stronger than any man's mind, since God's divine plan is irrefutable.
Or, if we understand "Fate" in a Naturalist reading, again, Fate is usually (but not always) stronger than man's mind. In Naturalist literature, a character is the victim of his/her natural and cultural environment. In this poem, it is the seafarer against nature ("the sea took me"). He laments his harsh life at sea, and feels he is at Nature's mercy. At the end of the poem, the seafarer conflates this idea of Nature's control of his fate with the will of God. So, this Naturalist reading goes along with the first reading of Fate as God's divine plan.
This is the reading in the poem, that Fate is stronger than man's mind. It is only when the seafarer accepts his fate (or his role in God's plan), that he loses his fear.
He who lives humbly has angels from Heaven
To carry him courage and strength and belief.
In the end, the seafarer puts most, or all, of his hope in Heaven. He has accepted his fate.
Outside of this poem, the question of fate vs. man, man vs. nature, or the power of free will is more debatable. In terms of Naturalism, the debate boils down to man's ability to determine his future, given the natural and social elements of his environment and place in history.