The enigmatic Bob Dylan is said to have "absorbed the spirit of his age" and, perhaps for this reason, he himself gave no explanation for the line "blowin' in the wind." An examination of the "winds" of the times may be the only way to provide an explanation.
It is well known that Dylan was an admirer of folk singer Woody Guthrie, who at one time compared his political sensitivity to newspapers that blew in the winds of New York City streets and alleys. In other words, the headlines were there one day, then gone the next day without many even knowing what was printed there. So, Dylan's line "The answer, my friend, is blowin' in the wind" pertains to the social instability of the 1960's, the changing political climate, and even some people's inattention to these changes. In other words, Who knows? What is today may not be tomorrow, and who is paying attention?
Here is what a twenty-one-year-old Bob Dylan himself said in response to what the phrase under question meant,
I still say it’s in the wind and just like a restless piece of paper it’s got to come down some ...But the only trouble is that no one picks up the answer when it comes down so not too many people get to see and know . . . and then it flies away.
About his own work, Bob Dylan once remarked that people should not create anything because that creation will always be misinterpreted. "And it will follow you." Called the "poet of our time" by Johnny Carson, Bob Dylan wrote songs in several genres in his efforts to not be categorized. Evidently, he found people's tendencies to label and categorize things as far too simplistic.