A folding knife has mechanisms for facilitating dual operational modes for opening the blade. In a first modality, the knife is opened and closed manually. In a second modality, the knife is fully automatic. When the blade is in the closed position the user may use either mode, manual or automatic, without any switching mechanism. A lock securely locks the blade in the open position when either opening modality is being used. To open the blade manually, the user rotates the blade from the closed to the open position—the lock automatically locks the blade open when the blade is fully open. To open the blade automatically, the lock mechanism functions as the trigger mechanism; the user slides the lock mechanism to actuate the automatic open mechanism. When the blade is in the fully open position the lock secures the blade open. A torsion spring around the pivot shaft that connects the blade to the handle and which is retained in a bushing drives the blade open in the automatic mode. The knife includes a “dry fire safety” mechanism that prevents operation of the automatic opening mechanisms when the blade is in the open position or in any position intermediate between open and closed when the manual modality is used.