The Earth is spherical in shape.

Edl's responses are much the same as they have been in the past, which is good -- because it allows us to now get into the fun part of the debate. I chose each of these arguments not because they are bar-none the best possible arguments for a round earth, but because they are by far the easiest to understand. Because of this, we can more quickly approach the truth than with complicated and dense arguments. Burdens Before we get into the arguments, I'll again discuss burdens. As I mentioned in the first round, it is not my burden to absolutely prove a spherical earth, but rather present such evidence that it is extremely likely. This way stated in round 1 and I even offered to Edl that I would make changes to the initial round if he wanted. No changes were requested, so my burden remains the same. The reason why I won't and indeed can't provide absolutely irrefutable evidence that the earth is round is because there are certain epistemological limits in place that make absolutely proving almost all things impossible. The "brain in a vat" argument excellently illustrates this idea. [1] While that could be an entire discussion in itself, suffice it to say that it's technically possible that everything we experience is false, thus nothing can be proven absolutely. Again, I stated in the initial round that my burden isn't absolute proof; it's to present sufficient proof. I stated that sufficient to mean there is no reasonable probabilistic alternative to the round earth. Photographic Evidence In paragraph 1, the opponent makes reference to computer generated images and ends with the following statement: "[Me] and NASA even admit that [most images of the earth from space are computer generated], so why should we consider any images from the same source as real? " This is a fair question. If an entity is (a) capable of creating CGI images and (b) *has* created CGI images, how can we trust that other images by that entity are not CGI? There are a few things to consider when making this judgment. Can the entity be trusted? Can the entity get away with lying to us? The answer to the first question is seen in the fact that, when NASA releases CGI images, it makes a disclaimer that the image is a visualization. Note on the following "Earth Images" page of NASA that when a suspect picture of the entire earth is shown, they clearly mark in the description that it is a visualization. [2] NASA does more than this -- they also note when the image is a panorama and when the image is a composite. It makes sense that they do this, NASA's entire budget relies upon whether or not the public has faith in the program. If NASA is capable of rendering perfect and believable CGI images, there is no reason they'd release some CGI images and call them such, while also releasing other CGI images and claiming they're real. The second question, however, is the more powerful one. Could NASA get away with releasing CGI photos labeled as real? I have already analyzed the diplomatic incentives for other countries (Ie, Russia) to release any proof of a non-round earth as quickly as possible. As a brief recap, at least Russia, China and the US have claimed to be in space. (This was sourced. ) As such, each country should know the shape of the earth and they should have minimally photographic evidence of this. If one country, such as the US, started lying to their citizens about the shape of the other, another country, like Russia, would have a massive incentive to release the details regarding the Earth's actual size. This would create massive distrust in our government, damaging our democracy and thus strengthening Russia's political position. The only thing stopping this power play by another country would be a global international conspiracy and I stated that there was no reasonable justification for this. The opponent offers two possible justifications. The first is the resources argument. The opponent asks, "what if things like gold, oil, land, water, food etc. were not rare? " This argument doesn't seem to do much but offer a "what if", without any sort of evidence based justification for it. I mentioned earlier that my burden is to show the earth has a very high probability of being round and this argument does little to thwart that. Simply offering alternatives that are only possible in the technical sense does nothing if these alternatives aren't analyzed and found to be of any reasonable likelihood. The Earth has many resources and most resource disputes are between countries. Maintaining an international conspiracy does not somehow alleviate the fact that the US wants the Middle East's plentiful oil. Oil is not suddenly easier to get if citizens are misinformed about how much oil there is. Beyond this, there does not need to exist an international conspiracy regarding the shape of the earth in order to lie about the amount of resources on the planet. In short, this "alternative" doesn't make sense at a fundamental level and, thus, does little to affect the probabilities involved in the shape of our planet. His second argument is more interesting, but even less concrete. He suggests that our ancestors were super intelligent beings who want us to continue to believe in the Big Bang theory so that we don't develop into moral creatures and try to find out "why we're here, and for what purpose. " There is absolutely no evidence or application of logic that suggests this possibility should be considered reasonable. Beyond that, it fundamentally doesn't make sense. Humans already try to be moral and we have been searching for our purpose and origin for well over 2,000 years. In summary, the opponent believes that merely proposing unsupported alternatives somehow invalidates the logic and accompanying evidence I've provided. We clearly see that it doesn't; probability still heavily suggests that photographic evidence is sufficient for belief in a round earth. Gravity I'm running short on characters, so I'm going to skip the rant regarding what the word "theory" means in the context of science. I direct readers to Google "what is a scientific theory". The opponent rebuts my claim that "some force pulls physical objects toward the planet" by claiming that "people knew the earth was flat for thousands of years" until Aristotle suggested the Earth was round and simply made up a "magical force" to explain how this was possible. I'll point out that gravity is easily observed on Earth. Hold something up. Let go. It falls. We call the force that causes the object to fall "gravity". It should be noted that objects did not start to fall only when Newton formalized the idea of gravity -- they've been falling for a long time. My second claim, which suggested that all pairs of objects mutually attract one another, is rebutted by my opponent who says that "[he] should be able to drop a wadded piece of paper off a sheer cliff and see that paper stick to the side". Since it instead falls to the ground, he argues, there must not be an attraction between the paper and the cliff wall. Let's recall from Physics I that the strength of a gravitational force between two objects is a function of distance and mass. Bigger distance, less attraction. Smaller average mass, less attraction. A simple force diagram clearly shows why a piece of paper falling from a cliff is dominated by the downward force of G(paper, earth) than the sideways force of G(paper, cliff). The mass of the earth is some 6e24 kg, while the mass of a cliff the size of Mt. Everest is less than 3e14 kg. In other words, the Earth has 10,000,000,000 times more mass, resulting in a significantly stronger downward force. Importantly, gravity is the only scientific theory that accounts for the behavior of falling objects. Mathematically speaking, it perfectly explains the regularly observed behaviors of moving objects. It explains why paper falls down, why planets orbit the sun, and why satellites orbit the earth. The opponent is free to call this force whatever he likes, but if he were to personally look at the behavior of moving objects and do calculations involved -- he would find that there is some force that acts on objects in a way that is *precisely* the same as how gravity is claimed to work on objects. As a final note on this point -- gravitational force is a function of mass and distance. The drawing of force diagrams shows what objects in a vacuum would experience, causing precisely what I described in the previous round to happen regarding the formation of a sphere in a vacuum. In summary, gravity is the best mathematical model we currently have for the behavior of objects. All observed evidence conforms to gravity and no existing evidence has been found which contradicts gravity. Therefore, there is sufficient evidence to believe in gravity beyond a reasonable doubt, which further necessitates a round earth, which satisfies my burden. Local Daylight Patterns I'm about out of room, but the opponent's argument here isn't well formed. I'll discuss more in the next round. A "smaller, closer sun" doesn't: 1. account for sunsets. 2. account for the fact that light radiates from the sun in all directions until it hits another object. Ie, the sun cannot "locally light" a flat surface. 3. account for the fact that "small suns" can't exist in a universe that obeys even the basic laws of physics A "small sun" theory doesn't make physical sense. I'm interested in the opponent's solutions to the above problems. Summary I have provided sufficient evidence that the earth is round. The opponent's responses seem to be composed of "what if" questions with no supporting evidence or logic. Sources 1. . http://www.iep.utm.edu... 2. . https://www.nasa.gov...