Question: "Sir, How consistent is the hardening of Pharaoh’s heart with the belief that humans possess free will?"

Answer: This is a case, in which God is described as being DIRECTLY responsible for that for which he is INDIRECTLY responsible in order to give him ULTIMATE responsibility. While it is stated that the LORD hardened Pharaoh’s heart (Exodus 4:21; 7:3; 9:12; 10:1, 20, 27; 11:10; 14:4, 8), it is also stated that Pharaoh hardened his own heart (Exodus 8:15, 32; 9:34; 1 Samuel 6:6). The plagues which God sent upon the Egyptians were the indirect cause of Pharaoh’s heart being hardened (see Exodus 9:13-19, esp. verse 14), but Pharaoh was the direct cause of his heart being hardened, and it was God’s purpose that was accomplished thereby. The New Testament, recognizing this fact urges, "Therefore, as the Holy Spirit says, ‘Today, if you hear his voice, do not harden your hearts as in the rebellion, as on the day of testing in the wilderness, where your ancestors put me to the test, though they had seen my works for forty years’" (Hebrews 3:7-9).