Atheists; what do you base your morals on?

[Mystic]

Logic? Could you elaborate?

Well there is properly basic praise. Then there is levels based on perception of the action.

But logic is one dimension of analyzing why an action is wrong. It isn't the case that logic is necessary for all good actions but it is the case that logic is needed for many good actions. It is not necessarily logic is needed to perceive why an action is evil, but reasoning is needed.

Logic however is needed to comprehend language, a situation, the complexity of other situations.

For example, why should I obey traffic rules. You use the following logic:

Severe harm sometimes comes out disobeying traffic rules and even deaths.
I am against harming (innocent) humans and causing death to them.
Therefore it's moral if I obey traffic rules to make it less likely that I cause severe harm or death to (innocent) humans.

In other words, you have primary belief in a moral. But logic is necessary to branch out that principle to other things.