 Malebranche does not quite say here why he thinks things known through simple perception are impervious to the omnipotent-deceiver doubt, though his examples provide some indication. Descartes himself had said that even a malicious demon could not make him doubt his own existence, at least while he is presently attending to this question. Such doubts are self-defeating: if the demon deceives me about anything then I must exist in order to be deceived. Rather than offering an explanation of this kind, Malebranche is content here simply to report on his own psychological response to the ‘extravagant supposition’ of a deceiving God, which fails to instill doubts in him about such simple truths. This supposition, however, does cause him to doubt things that depend on inference and here he is quite explicit that this is due to the fallibility of memory.