Numerical studies of the Hubbard model and its strong-coupling form, the t-J model, show evidence for antiferromagnetic, dx2−y2-pairing and stripe correlations which remind one of phenomena seen in the layered cuprate materials. Here, we ask what these numerical results imply about various scenarios for the pairing mechanism. PACS: 74.20Mn, 71.10Fd, 71.10 Pm Typeset using REVTEX ∗[email protected]...