( CNN ) -- On Tuesday night , it will be time to meet the candidates . Again . There will be a Republican presidential debate , this one hosted by CNN , the Heritage Foundation and the American Enterprise Institute . This is the 14th televised debate , depending on how you 're counting ( there was that two-person debate between Newt Gingrich and Herman Cain ) , since they began back in May . For generations we have taken it for granted that the way we meet our would-be presidents is on television . But , of course , it was not always so . For a good portion of the existence of the United States , the process of choosing a president must have felt like trying to decipher a distant and indistinct rumor . `` Every generation , because of advances in communications technology , thinks that it knows the candidates , and the president , better than the generations that came before , '' said John G. Geer , chairman of the department of political science at Vanderbilt University and co-director of the Vanderbilt Poll . `` But of course , it all comes down to the question : Even when we think we know a candidate , or a president , what do we really know ? '' Think of the earliest days of the United States -- and the earliest elections . Pamphlets , handbills , seventh-hand retellings of speeches the teller may or may not have actually heard ... the first ( and second and third and beyond ) generations of Americans elected as president men who , if they had passed them on the street , they might not have recognized . Geer believes that readers of American newspapers in those days devoured them with a level of gratitude unfamiliar today : `` Reading the paper was seen as a treat -- today , there is so much information , on the Internet and everywhere else , that it overwhelms people . But readers eagerly looked forward to reading the papers back then , because that was their best chance to learn about the world . '' Most people today take it for granted that a president will be a constantly televised visitor in their homes -- it has never been any other way for them . But more than 70 percent of all U.S. presidents served in the years before television sets were first installed in homes . Harry Truman was the first president to appear on TV the way we know it ( although Franklin Delano Roosevelt took part in a television experiment at the 1939 New York World 's Fair ) . More than 60 percent of our presidents were never heard on radio ; Warren G. Harding , who entered office in 1921 , was the first to speak on commercial radio . The voice of Theodore Roosevelt , as large as he loomed in the American mind , was never heard in American homes when he was in the White House . What in our era that would be unthinkable -- a president who did not regularly speak to us -- was , to Americans of a century or so ago , just a fact of life . Rutherford B. Hayes was the first president whose voice was recorded . The first to be filmed was William McKinley , who took office in 1897 . Before McKinley , presidents appeared to the public only in still photographs . And almost a quarter of our presidents did n't have their pictures taken while in office or running for office . James K. Polk is widely believed to have been the first ; George Washington , Thomas Jefferson , James Madison , James Monroe ... the Americans they led had no opportunity to see , photographically , what they looked like . In that era , voters could view their presidents and would-be presidents through reproductions of oil paintings of heroic-looking figures ( put forth by the men themselves ) or crude and insulting cartoons ( put forth by their opponents ) . All of this has little to do with the presidents -- they had no control over the technology of their times -- and everything to do with the citizens . It always has been such a leap of faith , deciding who is deserving of one 's vote . For all the media manipulation that goes on in the television age , consider the mischief that could be done in the era when presidents and candidates went largely unheard and , before that , unseen . The day is probably coming -- perhaps soon -- when some long-shot candidate will make a promise that , if elected , he will wear a tiny live video camera in the lapel of his suit jacket , so that Americans , in real time on their computer screens and telephones , can see and hear everything that he is seeing and hearing in the White House , from his vantage point . ( And if elected , he will quickly announce that for reasons of national security , he wo n't be able to use the lapel camera much , after all . ) The leap of faith is the same as ever . We have to tell ourselves that we know our presidents , even if we 've never met them . No American ever saw Herbert Hoover talking live on television ; no American ever heard Ulysses S. Grant speaking on the radio ; no American ever heard Abraham Lincoln 's recorded voice . John Adams ? No American ever saw a photo of him . Yet they all had to find a way to appeal to the entire country -- to get the majority of the nation to declare : He 's the one . Every four years , we roll the dice anew . Do we truly know the people who would be president any better now than our ancestors did when they had never seen the candidates ' faces or had any idea what their voices sounded like ? Of necessity , each generation evaluates a candidate -- and a president -- based on what the voters have available at the time . Vanderbilt 's Geer said that we sometimes forget the specifics of that and the limitations . `` Before microphones , the candidate with a booming voice had a great advantage , '' he said . `` Think about it . When candidates had to speak to large crowds without the benefit of a microphone , a person with a quiet voice did n't even stand a chance of reaching the crowd and having his words heard . '' In the end , though , according to Geer , all campaigning through various forms of media provides only a rough facsimile of what the person asking for votes is like . `` Imagine if every person in the country was somehow able to have a five-minute meeting with a candidate for president , '' he said . `` Just the two of them , alone . I think we all would have a very different feeling about who we 're voting for . I think that would change everything . '' The opinions expressed in this commentary are solely those of Bob Greene .
Americans think they know their presidents because they are always present on TV . Bob Greene : For much of America 's history , access to presidents was very limited . The first president who had a regular television appearance was Franklin D. Roosevelt in 1936.