The laws of logic

What is the difference between the laws of logic and the laws of physics? The laws of logic are aimed at the attainment of truth; the laws of physics merely describe physical phenomena. When we think, our thought has to be a certain way in order to get at the truth. In order to get at the conclusion Socrates is mortal, we have to reason from the premise All men are mortal, and Socrates is a man. Using premises such as Cheese is yellow, or My dog is loyal isn't going to get us there. But why is it that only certain premises lead to true conclusions? Why can't we use any premises we want? Why can't I prove God's existence using the premise The wall is hard? Because Reason says you can't. The laws of logic mandate that from The wall is hard you can deduce true conclusions, like I can't walk through it, or conditionals like If I hit the wall as hard as I could, then I would feel pain. But, for some odd reason, I am forbidden to conclude God exists, or Obama is a bad president. Isn't this strangely mysterious? The laws of physics tell me what is in this world; the laws of logic tell me what must be in this world, and in all possible worlds.

And notice that the notion of truth is assumed by the laws of logic. For I can't say one is forbidden from concluding Obama is a bad president from The wall is hard, unless it is that I can't make such a deduction. And it's the same with valid inferences: I can't appropriately conclude Socrates is mortal from Socrates is a man unless it is true that Socrates is a man, or that Socrates is mortal.