Response from Joseph G. Moore on October 25, 2005

Although "mental content" is a term of art, and used in different ways by different philosophers, most take it to be the way--the proposition or information--that a mental state represents the world as being. My belief that Bush is president and my belief that Alaska is large differ in mental content--the first represents the world as containing a guy named "Bush" who is president, the second a large state called "Alaska". By contrast, my belief that it's sunny outside and my desire that it be sunny outside share the same mental content, though they constitute different attitudes towards this content.

Even if this notion of mental content is clear enough, there are a number of important and unsettled issues surrounding it. One prominent issue is whether (and if so exactly how) the contents of our mental states are determined by features beyond the surface of our skin--most notably our environment and socio-linguistic setting. See http://www.amherst.edu/askphilosophers/question/13 for more on this. Perhaps that is what your worry concerns.

Response from Peter Lipton on October 25, 2005

Carrying on from Joseph's answer, part of your question is whether content is relative to the person entertaining that content. One sense in which this is right concerns representations involving ingredients like 'I', 'here', or 'now'. These so-called indexical terms have the interesting feature that what they refer to depends on who is thinking them. So we could both entertain the content 'I am an avid squash player': when I entertain this thought it is about me and when you entertain the thought it is about you (and maybe it is true when I think it and false when you think it). So that is one way in which what a thought or a thought's content is about can depend on who is thinking it.