The standard account of informed consent has recently met serious criticism, focused on the mismatch between its implications and widespread intuitions about the permissibility of conducting research and providing treatment under conditions of partial knowledge. Unlike other critics of the standard account, we suggest an account of the relations between autonomy, ignorance, and valid consent that avoids these implausible implications while maintaining the standard core idea, namely, that the primary purpose of the disclosure requirement of informed consent is to prevent (...) autonomy-undermining ignorance. The problem with the standard account, we argue, is that it fails to distinguish between different forms of ignorance–in particular, error and suspending ignorance–that have very different effects on individuals’ ability to provide valid consent. While error often undermines our ability to provide valid consent, suspending ignorance, we argue, does not. Once the moral weight of this distinction is appreciated, it becomes apparent that valid informed consent requires far less knowledge than suggested by the standard account. (shrink)