liar paradox; libertas; Lobachevsky Nikolai Ivanovich; Locke John; locutionary act; logical form; logical positivism; logicization of arithmetic; logos - mythos; Lombard Peter; Lorenz Konrad; Lotze Rudolf Hermann; Lovejoy Arthur Oncken; Lucretius Titus Lucretius Carus; Lukacs Grygory; Lukasiewicz Jan; Luxemburg Rosa; Lyotard Jean-Francois;