What are the reason why Bob Dylan wrote the poem 'Blowin' in the Wind'?

Although it has been described as a protest song, it poses a series of questions about peace, war and freedom. The refrain "The answer, my friend, is blowin' in the wind" has been described as "impenetrably ambiguous: either the answer is so obvious it is right in your face, or the answer is as intangible as the wind"