“Logic and truth, as a matter of fact, have very little to do with each other. Logic is concerned merely with the fidelity and accuracy with which a certain process is performed, a process which can be performed with any materials, with any assumption. You can be as logical about griffins and basilisks as about sheep and pigs.”

…

“Logic, then, is not necessarily an instrument for finding truth; on the contrary, truth is necessarily an instrument for using logic – for using it, that is, for the discovery of further truth and for the profit of humanity. Briefly, you can only find truth with logic if you have already found truth without it.”

Source: Basic Philosophy, by way of Confessing Evangelical, by way of BlogCritics, by way of Google Alerts. (Apologetics)