exposure to multiple sources is a necessary feat ure of any mo del of compet ition because that is the source of competit ion. If readers are in contrast isolated and read ol source, we would simply apply the results of the previous sect ion and assume it is a ase of local monopoly. In what follows, when we speak of the number of newspapers, ve mean the number t hat the reader is act ually exposed to lly, we assume that newspaper payoffs are independent. That is, a newspape receives the same payoff T for being perceived as good independent of t he number of ot her newspapers The effect s of compet ition we discuss arise purely from informat ion aggregation rat her than market structure Suppose that agent s are Bayesian. If newspapers have different enough ideologies, the average news story is an unbiased est imate of the truth. Each newspaper may bias news towards it s ideology but these differences wash out in the aggi Proposition 3 Suppose agen ts are Bayesi an and the n um ber cf n ewspapers having a positive ideology is the same as the number of newspapers having a negative ideology. Then in aggregate there is no bias in beliefs. That is, the readers beliefs after reading all the n ewspaper stories (v) are the same as if he could see the true news(n) himseif. If there are enough left-wing and enough right-wing papers, the trut h about Clinton emerges. Each side may exaggerate the story in it s preferred direction, but these exaggerat ions cancel out While compet ition eliminates the bias caused by ideology, it does litt le to reduce spin, the bias caused by categoriz at ion. To underst and why this is the case, note that each newspaper reporting a story st ill feels the need to go along with the reader's priors But now that effect is reinforced because each newspaper knows that future newspapers will also cater to the reader's beliefs at the time. Since each of the prior newspapers has biased the news, the reader is now stronger in his beliefs. Each newspaper, therefore, feels an even greater pressure to bias toward priors 1 7 This caveat must be kept d when interpreting our results on ide cal competition In our mode deological competition refers to competition within the set of news-papers a reader reads. If every reader is segmented to a parti cular ideological paper then ideologi cal diversity would of course create an adverse effe ct on accur acy which is not in this mo del. But remember that we are intere sted in the case of a motivated reader who is try ing to get to the truth by consulting many sourcesexposure to multiple sources is a necessary feature of any model of competition because that is the source of competition. If readers are in contrast isolated and read only one source, we would simply apply the results of the previous section and assume it is a case of local monopoly. In what follows, when we speak of the number of newspapers, we mean the number that the reader is actually exposed to.17 Finally, we assume that newspaper payos are independent. That is, a newspaper receives the same payo  for being perceived as good independent of the number of other newspapers. The eects of competition we discuss arise purely from information aggregation rather than market structure. Suppose that agents are Bayesian. If newspapers have dierent enough ideologies, the average news story is an unbiased estimate of the truth. Each newspaper may bias news towards its ideology but these dierences wash out in the aggregate. Proposition 3 Suppose agents are Bayesian and the number of newspapers having a positive ideology is the same as the number of newspapers having a negative ideology. Then in aggregate there is no bias in beliefs. That is, the reader's beliefs after reading al l the newspaper stories () are the same as if he could see the true news (n) himself. If there are enough left-wing and enough right-wing papers, the truth about Clinton emerges. Each side may exaggerate the story in its preferred direction, but these exaggerations cancel out. While competition eliminates the bias caused by ideology, it does little to reduce spin, the bias caused by categorization. To understand why this is the case, note that each newspaper reporting a story still feels the need to go along with the reader's priors. But now that eect is reinforced because each newspaper knows that future newspapers will also cater to the reader's beliefs at the time. Since each of the prior newspapers has biased the news, the reader is now stronger in his beliefs. Each newspaper, therefore, feels an even greater pressure to bias toward priors. 17This caveat must be kept in mind when interpreting our results on ideological competition. In our model, ideological competition refers to competition within the set of news-papers a reader reads. If every reader is segmented to a particular ideological paper, then ideological diversity would of course create an adverse eect on accuracy which is not in this model. But remember that we are interested in the case of a motivated reader who is trying to get to the truth by consulting many sources. 13