jonathan karl talks with the historian michael beschloss about his twitter feed full of incredible historical photos. >> i always felt that in history images tend to be underrated. we write books and they're based on letters and documents, the usual sources. but oftentimes i like it to look at pictures from the time or about people i'm wroiing about because i think they can tell you an awful lot. that's why i think it works on twitter. >> and to teddy goth, the former digital director of the 2012 obama campaign, about the role of social media and modern politics. >> you mentioned that the president had 34 million facebook fans on election day, a little higher now. those people were friends with 98% of the u.s. facebook population. that's actually more than the number of people who vote in this country. so we knew that if we talked to them in the right way, served them with an experience that they enjoyed, gave them reason to feel inspired and stick with us and maybe hit the share button every once in a while we could reach almost everybody that way. >> foreign policy and social media next. >>

expert witness in the same-sex marriage cases decided last week, and presidential historian michael beschlossd michael le let me ask you to set the frame for us to start off here. the supreme court in one week tackling major issues that resonate through american history. >> yes, you know, oftentimes you go through a week like this and there may be cases that are interesting now but not likely to be written about later on, the historian 50 years now if they are writing a general political history of the united states i think will be very hard for them to write about this period without writing about what happened last week, three cases particularly that do have to run all the way through american history. >> ken net mac did you see a broad theme in these cases either in the kind of issues they were tackling or in the out comes? .. >> yes, i agree with michael beschloss, that history was invoked in actually all of the cases, history to invalidate a section of the voting rights act, history in the sense that chief justice roberts says voting discrimination of the kind that this section was tryin

and presidential historian michael beschloss. welcome to everybody. leonard pitts why don't you start it off. generally what is your reaction to what the president said? >> my general reaction is glory hallelujah and thank goodness when he already said it. there is no political upside. but morally and socially, i believe and i believe he came to the conclusion that as the nation's first african american president there is no way that he could stand on the sidelines on this. he had to, to speak to these issues and he had to call the nation to account, not so much in terms of what happened legally, in that courtroom in florida, but in terms of the moral implications of it. in terms of this idea that seems to be bandied about that somehow it's trayvon martin's innocence or guilt that is in question, or that mr. zimmerman had every right to talk strm because of perceived danger because of the color of his skin. that needs to be called into account and i think the president did a pretty good job of doing so. >>brown: carol swain, what did you think? >> the