 Dretske appreciates that a given behavior on Tom’s part is not always a reliable indicator of, say, anger. What he holds is that under certain conditions and to those who know Tom well—such as his wife—his behavior can be taken to be a reliable indicator of his anger (for a critique of this idea see Avramides forthcoming). Therefore, according to Dretske, we can have direct perceptual knowledge of another’s mental states in the following sense: we can see that others are in pain, angry and the like, even though we cannot see another’s mental states or know that solipsism is  false.[7]