Biology Forums - Study Force

The Boy Scouts of America is no different from any other public organization such as
  Rotary or the Kiwanis Club. Thus, its policy of excluding girls is discriminatory and ought to
  be eliminated.

(Argument from analogy. The only common feature mentioned is being a public
organization. Since public organizations are required to be nondiscriminatory in
their membership, it would seem to follow that the BSA should be, too.)