Metaphysical déjà vu: Hacking and Latour on science studies and metaphysics: The Social Construction of What? Ian Hacking; Harvard University Press, Cambridge, Mass. and London, England, 1999, pp. x+261, Price £18.50 hardback, ISBN 0-674-81200-X.Pandora's Hope: Essays on the Reality of Science Studies Bruno Latour; Harvard University Press, Cambridge, Mass. and London, England, 1999, pp. x+324, Price £12.50, $19.95 paperback, ISBN 0-67-465336-X, £27.95, $45.00 hardback, ISBN 0-67-465335-1.