 About the same time, however, Hempel found reasons of his own for doubting that the analytic/synthetic distinction was tenable, which surfaced in his study of dispositional predicates, such as “malleable”, “soluble” and “magnetic”. They designate, not directly observable properties, but (in the case of “magnetic”) tendencies on the part of some kinds of things to display specific reactions (such as attracting small iron objects) under suitable conditions (such as the presence of small iron objects in the vicinity). It is very tempting to define them using the material conditional, “___ \(\supset \ldots\)” by definitions like,