Induction is not necessarily truth preserving . Deduction is erosion-proof. New premises may completely undermine a strong inductive argument. Induction is not erosion-proof . An argument is totally valid, or it is invalid.
Inductive arguments come in different degrees of strengt h.
In some inductions the premises support the conclusions more strongly than in others. Introduction to the Philosophy of Science . Merilee H. Salmon, John Earman, Clark Glymour, James G. Lennox, Peter Machamer, J.E. McGuire, John D. Norton, Wesley C. Salmon, and Kenneth H. Schaffner. Prentice Hall, 1992.