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Deductive argument

Working with reduction ad absurdum

Identify the reduction ad absurdum argument pattern in each of the passages below. That is, specify the claim to be proven, the assumption that is made, the conclusion that one is supposed t have to draw from that assumption, the reason for thinking that conclusion to be implausible, and the final conclusion of the reduction argument.

Some people believe that ordinary citizens should be allowed to own any weapon that they want. Suppose that this were true. That would mean that ordinary citizens could own tanks, large stockpiles of explosives, fighter jets- even nuclear bombs! Clearly, ordinary citizens shouldn't be allowed to own nuclear bombs. Thus, it's false that ordinary citizens should be allowed to own any weapons they want.

There's a popular myth out there that aliens were somehow involved in building the pyramids of Egypt. Assume, just for the sake of argument, that aliens really did build the pyramids. As anyone who's been to the pyramids can tell you, the stones used in building the pyramids were clearly shaped by simple hand tools. You can see the chisel marks on the stones. This would mean that despite having the ability to reach Earth from some distance planet, the aliens would have had to rely on the Egyptians' basic hand tools to shape the rocks. It's ridiculous to think that any civilization with the technology for interplanetary travel wouldn't have used something like a laser- or at least a high-powered, precision saw- to carve the stones used in the pyramids. That's why I don't believe that aliens were involved in building the pyramids.

The police claim that the defendants were using an elaborate code to arrange drug deals. The police also claim that they didn't know about this code before they arrested the defendants a few hours ago. Suppose they're telling the truth. That would mean that the police cracked this elaborate code within a matter of hours. There's simply no way they could have pulled that off. It's impossible for the cops to have cracked such a sophisticated code so quickly. Thus, the police must have known about the code before the arrests.

Physicians have proven that many features of our universe are "fine tuned" for the existence of life as we know it. That is, things like the strength of the force of gravity are just right to make life possible. If they were very slightly different, there would be no life at all. If we assume that the universe is not designed by an intelligent creator, then the "fine tuning" is just a freak accident. It is wildly improbable that the physics of our universe must be so perfectly adjusted for life by accident. Thus, the universe must be designed by an intelligent creator.

God is the greatest being that you can possibly image. This implies that you cannot imagine a being that is greater than God. Now, suppose that God did not exist. Then you could image a being that is exactly like God except that it exists. Since its better to exist than not to exist, such a being would be even better than God. Thus, you would be imagining a being that is greater than God- even though you cannot image a being that is greater than God. So, God must exist.

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Many of these can be fit into additional categories, since really, all fallacies are the same: the consequent is not contained in the major premise or its minor qualifier.

First, Find the Reductio ad Absurdum:
Some people believe that ordinary citizens should be allowed to own any weapon that they want. Suppose that this were true. That would mean that ordinary citizens could own tanks, large stockpiles of explosives, fighter jets- even nuclear bombs! Clearly, ordinary citizens shouldn't be allowed to own nuclear bombs. Thus, it's false that ordinary citizens should be allowed to own any weapons they want.

Concept is that, in accepting or rejecting someone's position, absurd and crazy things will happen.
This is easy, The concept of owning nuclear weapons. The reductio is dishonest because the results are taken to extremes and are not contained in the opponent's argument. It is a tactic that results in nuclear weapons=being against gun control.

Second
There's a popular myth out there that aliens were somehow involved in building the pyramids of Egypt. Assume, just for the sake of argument, that aliens really did build the pyramids. As anyone who's been to the pyramids can tell you, the stones used in building the pyramids were clearly shaped by simple hand tools. You can see the chisel marks on the stones. This would mean that despite having the ability to reach Earth from some distance planet, the aliens would have had to rely on the Egyptians' basic hand tools to shape the rocks. It's ridiculous to think that any civilization with the technology for interplanetary travel wouldn't have used something like a laser- or at least a high-powered, precision saw- to carve the stones used in the pyramids. That's why I don't believe that aliens were involved in building the pyramids.

Simple problem of contradiction. Assuming (for the sake of argument) of course, cannot have real life consequences.

Third
The police claim that the defendants were using an elaborate code to arrange ...

Solution Summary

The solution discusses the deductive argument.

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