 The general Academic tactic against this view was to concede the possibility that an impression might meet conditions [a] and [b], but argue that condition [c] never obtained. They appealed to our experience of twins etc. and in abnormal states such as dreams, illusions and episodes of madness to show that it was always possible to have a false impression with exactly the same richness and detail of representation as a true one; it follows that meeting condition [b] could never suffice to show that condition [c] obtains, with the result that the warrant claimed in [c] is never available to us. (See, e.g., Sextus M 7.402–10 &amp; Cicero Ac. 2.84–90).