Universality of Causality Principle

The causality principle is physically investigated in the framework of special relativity theory (SRT) and it is proven to be absolutely valid for subluminal, luminal and superluminal signals under any natural and/or artificial circumstances; also Einstein's thought experiment (1907), Tolman's paradox (1917), tachyonic antitelephone (1970) and Moller's thought experiment (1952) are re<i>-</i>examined in order to show more conclusively that the so<i>-</i>called causality paradoxes are in fact a pure mental construction resulted from some too<i>-</i>common misconceptions which mainly spring from the confusion between the concepts of (relative) velocity and (relative) speed. Thus, in light of the present work, the old and semi<i>-</i>persistent concern about causality violation by superluminal signals and its consequences at micro and macrophysical levels may be conceptually ruled out if one approaches the physico<i>-</i>mathematical formalism of SRT in an open<i>-</i>minded way.