Ethos

Just like your Facebook Newsfeed, Monroe's speech uses a bit of all the forms of rhetoric. However, the impact of his statement relies on the listeners' belief in the power and purpose of the United States, so the main form of rhetoric is ethos.

Monroe's words aren't personal—all the players in his speech are nations and continents. As president, he's clearly speaking on behalf of the United States. For instance:

In the wars of the European powers in matters relating to themselves we have never taken any part, nor does it comport with our policy to do so. It is only when our rights are invaded or seriously menaced that we resent injuries or make preparation for our defense. (9-10)

Monroe connects the people he's speaking to and the United States as one entity ("our policy"), and paints a picture of the U.S. as taking the moral high ground in the past. The nation only fights when forced to.

A lot of the Monroe Doctrine is based on the idea that the American form of government is superior to the old, crusty monarchies of Europe. That's why the U.S. wants to protect those new Latin American republics, which have followed the Americans' lead.

He says that the European governments aren't interested in Latin America the way that the U.S. is:

We owe it, therefore, to candor and to the amicable relations existing between the United States and those powers to declare that we should consider any attempt on their part to extend their system to any portion of this hemisphere as dangerous to our peace and safety. (14)

Again, everything is argued in terms of nations. His argument is that America's wishes should be respected because of how it has conducted itself in the past (friendly), and how it as a nation would perceive certain actions.

Monroe repeatedly invokes the past and present behavior of the U.S. as a whole to argue that European countries should pay attention. He reminds the audience that:

Our policy in regard to Europe…is, not to interfere in the internal concerns of any of its powers. (21)

Monroe continues to present America as the super cool, well-behaved gentlemen across the Atlantic who has nobly cultivated liberty and not tried to butt in on the Old World's business.

Even at the end of this part of his speech, Monroe lays it on pretty thickly. Talking about how the Latin American republics would never adopt absolutism on their own, he says:

It is still the true policy of the United States to leave the parties to themselves, in hope that other powers will pursue the same course… (26)

In other words, "We're going to let the new kids follow their dreams, and we hope that other people will do the same (hint hint)."

The strength of Monroe's arguments relies on the audience's belief in the United States as a strong country with strong (and correct) ideals. The president invokes patriotic belief that America's conduct has been better that the other guys', in order to gather support for his bold statement of independence. Without that belief in America's righteousness, no one would follow the Monroe Doctrine, because why would you care?

Ergo (because you can never have too much Latin), the primary form of rhetoric in the Monroe Doctrine is ethos. Of course, there are elements of pathos and logos in there: pathos when he emphasizes the greatness of the U.S., whose freedom was won with a "loss of so much blood and treasure," (13) and logos because he presents arguments based on real past events to justify his argument.

In the busy, complicated world in which we live, nothing is just one thing. We have hybrid cars, hybrid fruits, and hybrid forms of rhetoric.

However, this text is definitely mostly using ethos.