 The logical forms of sentences are the ways that sentences are built up from the logical particles. From this perspective, to say that a wff B is a logical consequence of a set of wffs \(\Sigma\) is to say that the logical forms of B and the wffs in \(\Sigma\) are so related that if the wffs in \(\Sigma\) are true, so is B. Moreover, since logical form is sufficient to ensure this, for any argument of the same logical form, if the premises are true, so is the conclusion. This leads to the now familiar idea that