 Śrīharṣa responds to this objection with a regress argument. Suppose an agent is undergoing a conscious mental occurrence. Ordinarily, when we are aware of a conscious mental occurrence, we are also aware that we are aware of it, we are aware that we are aware that we are aware of it, and so on. Since the “higher-order awareness” (henceforth, HOA) theorist explains such awareness of one’s own mental occurrences by appealing to episodes of higher-order awareness, she faces a choice: either she should posit an infinite hierarchy of such episodes of higher-order awareness, or she shouldn’t. If she takes the second route, she would have to say that for any conscious mental occurrence, an agent is aware of that conscious mental occurrence, and aware that she is aware of that mental occurrence, and aware that she is aware that she is aware of that mental occurrence,…, and so on, until she reaches some higher-order awareness-episode which isn't the object of any further higher-order awareness-episode. But if that is the case, the agent can indeed doubt whether that final higher-order awareness-episode exists. On that basis, she can doubt the existence of the higher-order awareness-episode that the final higher-order awareness-episode has as its object, and so on. In this way, the agent can indeed come to doubt whether she is undergoing to the relevant conscious mental occurrence. Therefore, the HOA theorist must posit an infinite hierarchy of higher-order awareness episodes. But then there will be a regress. So, the HOA awareness theorist cannot really explain why conscious mental occurrences are immune to doubt (KKh 43).