Either these lights you saw in the night sky were alien spacecraft (ufos), or you were hallucinating. you obviously werent hallucinating. therefore, they had to be ufos. this passage contains the following relevance fallacy:

The UFOs

Explanation:

This person is saying that it either had to be hallucinogens or the UFOs which is false, because it could of been a number of things, ie. Comets, planes, helicopters, rockets taking off.

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