Description:
<jats:p>It has been shown by Lewis and Langford that the postulate B8,</jats:p><jats:p><jats:disp-formula><jats:graphic xmlns:xlink="http://www.w3.org/1999/xlink" orientation="portrait" mime-subtype="gif" mimetype="image" position="float" xlink:type="simple" xlink:href="S0022481200073977_eqnU1" /></jats:disp-formula></jats:p><jats:p>is not deducible in SI. From this it follows that neither are the paradoxes of strict implication deducible in that system. However, the following weaker—but perhaps philosophically equally important—analogues are deducible:</jats:p><jats:p><jats:disp-formula><jats:graphic xmlns:xlink="http://www.w3.org/1999/xlink" orientation="portrait" mime-subtype="gif" mimetype="image" position="float" xlink:type="simple" xlink:href="S0022481200073977_eqnU2" /></jats:disp-formula></jats:p>