Arguments Against the Portugese Theory
Just like the Norse Settlement Theory, this theory is entirely speculative, as there has been no definitive proof that Miguel Corte-Real was ever near what is today known as Rhode Island or Massachusetts.
It has been stated that it could have taken approximately one-and-a-half years to build the tower, which would mean that a settlement would have had to be built during this time period; however, no proof of a Portugese settlement has ever been found nearby.
Still others state that it is unlikely that the tower could ever have been used as a beacon because prior to the 18th Century, most beacons were simply elevated areas for a bonfire, rather than directional lighting.