The only type of person worth trusting is a liar. If a liar tells you that you can trust him/her, then you know that he/she is lying, thus, you can trust that the liar will lie. If a person claims to tell the truth, this is unreliable information, for this person could be lying and misleading you into believing that he/she tells the truth. Also, as an aside, what is the word for a person who speaks the truth?
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