Sartre's attack on the idea that consciousness has contents is, in effect, an attack on the idea that the mental possesses features that are hidden, inner and constituted or revealed by the individual's inwardly directed awareness. This attack is continued by the Austrian philosopher, Ludwig Wittgenstein. Although developing wide-ranging arguments concerning mentality in general, the focus of Wittgenstein's concern is items such as meaning and understanding - meaning something by one's use of a sign and understanding something by way of someone else's (or indeed your) use of a sign. Accordingly, I shall focus, at least initially, on these.