The tree of knowledge of good and evil

The name of this tree, The Tree of Knowledge of Good and Evil could be thought of in one or both of two different ways:
 * the tree that teaches good and evil
 * the tree that grants knowledge to judge between good and evil

The tree that teaches good and evil
This would mean that the Tree taught us good, and taught us evil. Before this, we didn't know to do good nor to do evil. It does not directly follow that this "learning" would cause us to know that there is a difference.

In this case the tree's fruit might represent curiosity without caution.

The tree that grants knowledge to judge between good and evil
This would mean that the Tree gave us knowledge about the difference between good and evil to give us the capacity to judge. This would hold us responsible for our choices, as well as that of others. (Leviticus 19:17 and Ezekiel 3:18 is further evidence of such a doctrine, however this may not be related to this Tree of Knowledge.)

The fruit of this tree might grant the knowledge that there is a difference and the desire to discover that difference. In parallel, the fruit would represent curiosity with caution.