Total Depravity (Total Inability)
Total Depravity is probably the most misunderstood tenet of Calvinism. When Calvinists speak of humans as "totally depraved," they are making an extensive, rather than an intensive statement. The effect of the fall upon man is that sin has extended to every part of his personality -- his thinking, his emotions, and his will. Not necessarily that he is intensely sinful, but that sin has extended to his entire being.
The unregenerate (unsaved) man is dead in his sins (Romans 5:12). Without the power of the Holy Spirit, the natural man is blind and deaf to the message of the gospel (Mark 4:11f). This is why Total Depravity has also been called "Total Inability." The man without a knowledge of God will never come to this knowledge without God's making him alive through Christ (Ephesians 2:1-5).