Bryan Caplan points us to a paper by Mankiw, Reis, and Wolfers on disagreement about inflation: The sticky-information model, according to which some people form expectations based on outdated information, seems capable of explaining many features of the observed evolution of both the central tendency and the dispersion of inflation expectations over the past fifty years.
I am not sure why disagreements over inflation expectations should indicate bias, unless one is a true believer in rational expectations. But even with that, one can believe that the market as a whole exhibits ratex, even while there might be a distribution of individual expectations around that rational core.
For that matter, the ratex forecast can be wrong, indeed always wrong. So, who is biased? The person who makes the correct forecast or the person who makes the incorrect but rationally expected forecast?
I didn't mean to imply we had no idea what others expect about inflation. I meant that our uncertainty about the beliefs of others is probably about the same magnitude as the variance in beliefs across people.
we do talk about inflation. not on a individual level but certainly on a meta level through newspapers and TV. we infer about others' inflation expectations in the smae way that we infer about many issues that don't affect us directly but we are interested in. from india(where i live) i am interested in US Presidential Elections '08 but not directly affected by it and have sometimes strong opinions about candidates. in summary i find it very hard to see how can there be no "knowingly disagreement" about anything in the world.