Hailed by Peter Schjeldahl as ''the most challenging painter in the recent history of art,'' Luc Tuymans (born 1958) is an artist whose most recent works always provoke excitement in the art world. Against the Day is a series of 20 new paintings that focus on the reality TV show phemonenon, and the manipulation of illusions and fantasies. The series title Against the Day is taken from Thomas Pynchon's novel of the same name-Pynchon being an old hand at such themes, which chime well with Tuymans' conviction that ''original pictures'' do not exist (he has previously referred to his own paintings as ''authentic forgeries''). These newest paintings can be seen as the third and last part of a triptych that began with Les Revenants (on the power of the Jesuits) and Forever: The Management of Magic, which explored the Disney industry.