In Act 1 of "The Crucible," why do Putman and Proctor get into an argument?

Thomas Putnam and John Proctor disagree on many issues, but in Act 1, one of their main arguments is about some lumber than John Proctor has hauled from his forest.  Putnam, who throughout the play is concerned with getting more land, claims that the woods from which Proctor got the wood, was his.  Proctor tells Putnam he bought the land five months ago from Giles Corey.  Putnam goes on to say that Corey never owned the land to sell because Putnam's grandfather willed the land to him, Thomas Putnam.  Proctor and Corey both point out that Putnam's grandfather may have written that in his will, but it was never his to bequeath to someone else in the first place.