A number of philosophers before Augustine had argued that certainty is impossible and that the best the human mind can hope to achieve is the conviction that its conclusions are highly probable. Augustine disagreed with this premise and sought to demonstrate philosophically that certitude is in fact possible. His first argument is that if we accept the possibility of our conclusions being probable, we’ve already implicitly assumed that certainty exists, because things can only be “probably” true if truth (in other words, certainty) does in fact exist. If there is no truth, there is no probability. Second, happiness is the result of acquired wisdom, which all human beings desire. Thus, to say wisdom cannot be attained is to say that happiness is impossible—an unacceptable conclusion. Third, Augustine takes issue with the idea that the senses cannot be trusted, and he does not agree with his opponents that the mind is entirely dependent on the senses. On the contrary, our senses do seem reliable to a certain extent, and the mind can understand things independently of the senses, so therefore it must be even more reliable than the senses. Finally, Augustine points out that our mental states are beyond doubt. Whatever we may say or not say, we cannot doubt that at this moment we are thinking. We may say that we are being deceived, but this very fact of being deceived proves that we exist. These four reasons support the thesis that certitude is possible.