"est tamen et ratio, Caesar, quae moverit illum / erroremque suum quo tueatur, habet."
"There is nevertheless also a reason, Caesar, that influences him and is able to make his own discrepancy thereby defensible [wherefore it/he would/could defend]"
habeo = to have the knowledge, means, ability, be able, know how to do or say anything (L&S)
I'm writing in Latin hoping for correction, and not because I'm confident in how I express myself. Latinè scribo ut ab omnibus corrigar, non quod confidenter me exprimam.