Firstly: Note that both mines can't be in the top two spaces - i.e. there must be a mine here:
From that you can see there can't be a mine in the middle space - so the two mines must be at the top and the bottom of the column of three and not in the middle.
In terms of whether it is solvable or not: the only real way to tell is if the puzzle has multiple solutions - i.e. you can place the mines such that the conditions of the puzzle are satisfied in more than one way. In this case, the only possible solution is the one described.