We study the possibility that the light scalar mesons are (q) over bar(2)q(2) states rather than (q) over bar q. We perform a lattice QCD calculation of pseudoscalar meson scattering amplitudes, ignoring quark loops and quark annihilation, and find indications that for sufficiently heavy quarks there is a stable four-quark bound state with J(PC) = 0(++) and non-exotic flavor quantum numbers. (C) 2000 Elsevier Science B.V. All rights reserved.