A "paradox" has been compared with a "paralogism" (7rapa, X6 yos, reason), as that which is contrary to opinion only and not contrary to reason, but it is frequently used in the sense of that which is really absurd or untrue.
In 1628 Castelli published a small work, Della misura dell' acque correnti, in which he satisfactorily explained several phenomena in the motion of fluids in rivers and canals; but he committed a great paralogism in supposing the velocity of the water proportional to the depth of the orifice below the surface of the vessel.