A "conspiracy theory" is rather different. That term refers to belief in a conspiracy in the absence of any evidence for it. "We faked the moon landing"
Everyone knows it just means the theory for a conspiracy. Conspiracies are common as dirt. Husbands conspire against wives as they cheat and vice versa.
Adam Smith wrote
"People of the same trade seldom meet together, even for merriment and diversion, but the conversation ends in a conspiracy against the public, or in some contrivance to raise prices."
Every government on the earth conspires against their people from time to time, because lying is easier than telling the truth and nobody likes giving up power (and its access it gives to wealth and status).
But better is the specific example you gave. The moonlanding.
Funny you say that.
A. Reasons why it's fake:
1. A number of nasa spokespersons have said we currently don't have the technology to get people safely beyond the van allen belts and thus we don't have the technology to get people to the moon
2. The astronauts that went were unable to tell us if they saw stars or not from the moon in the first press conference
3. All telemetry data and recorded video have been lost by Nasa, besides the videos that are already in the public domain.
4. The videos that people have seen was news broadcasts that set their camera to film in black and white, the color screen at Nasa that showed the video of the moonlandings.
5. When the president "phoned" to the people on the moon, there was no time delay, though you can calculate what the time delay for radio signals would be (2.5 seconds).
6. A number of the official videos have anomalies that are strange, like the rotating head in one spacewalk.
7. The people that died in the challenger all have living twins and/or dopplegangers:
8. Some dutchies tested the moonrock received and found outnit was petrified wood. (It was later claimed they tested the wrong sample)
B. Reasons why it's not fake
1. The retroreflectors placed on the moon show that at the very least we landed something on the moon, with or without humans
2. Why didn't the russians claim it was false (did they actually know? How would they have known or be able to prove it at the time?)
3. How could such a large conspiracy be maintained?
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C. What could be reasons for faking it?
1. The US lost every step of the space race, so this would be a way to leap forward and beat the USSR in the PR coup of the century.
2. Warfunding was getting less and less popular with the vietnam war and the hippie movement. This would have allowed extraordinary funds to go to rocket technology such as the minuteman II for intercontinental nuclear missiles, which was developed at the same time.
3. Its easier to fake something than to do it for real.
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Would it be a conspiracy theory to say that OJ Simpson killed his wife? There was evidence for it. There was evidence against it. According to court of law he did not do it. According to his later book "if I did it" he gives a supposedly fictional account of how he would have murdered her if he would have murdered her.
Of course you would have to be a conspiracy nut, a kook, an alex jones, a paranoid kiwifarmer to possibly believe the conspiracy theory that OJ Simpson killed his wife.