If you don’t think it’s possible to know the truth, perhaps you are a skeptic. A definition for a skeptic is “One who is yet undecided as to what is true; one who is looking or inquiring for what is true, for facts or reasons.”
While healthy skepticism may be necessary to discover the truth, contemporary society has produced a number of critics who doubt everything…except for a few things THEY deem true. In some cases, they even deny that truth can ever be known (except, as it turns out, truths needed to support their skeptic’s assertions).