One reason that presidential debates are important is because they help voters learn about candidates, and subsequently how to vote. For many, these debates are what they reply upon when deciding how to vote. For example, in the 1960 election, Nixon gave the impression of being shifty and nervous in comparison to J.F. Kennedy who seemed youthful and energetic. He went on to win the election and historians generally agree that the debates had a profound impact on the result, therefore presidential debates can be seen to be important as they affect how voters vote, and therefore who wins. However, presidential debates are not important as they do not actually affect how the voter votes. The unimportance of debates can be seen through the polls, the average shift being 2.3% which is an unlikely amount to shift the result of an election. In fact, the polls have shown that debates have only shifted the results in two different elections - in 1980 and 2000. This shows how debates do not have a significant affect on the polls (which are a good indicator on how people vote) and this therefore shows that debates do not really change how people vote and so are not important.
Another reason that presidential debates are important is because they play a role in 'agenda setting'. They bring attention to a policy or campaign issue to the public mind which means it could become more likely to happen and actually forces candidates to see their promises through and informs the public what they are actually voting for. For example, Donald Trump emphasised how he would put money into improving infrastructure. This encouraged and secured votes for him from middle class workers in particular. He is now expected to fore fill these promises. This shows presidential debates are important as they begin to set the president's future agenda and make it aware to the public. However, the reality is that what presidential candidates promise in a debate does not mean that they do it. There is no enforcement or rule to actually put into action your promises. For example, Trump said that he would begin to improve infrastructure yet he has not began to do so yet significantly. This shows that presidential debates are not important because the candidates do not have to do anything that they say in those debates.