Can we logically deduce what is good and bad to the point that it is objective truth?

[Microcosm]

If you don't know about the theory of forms, here is a web page: Wikipedia Page (http://en.wikipedia.org/wiki/Theory_of_Forms)

I was conversing with my brother today about the theory of forms, and he simply wrote it off as an "unfalsifiable" theory. What he meant by this, of course, was that if it is impossible to prove it wrong or correct then there is no point in indulging it and discussing it.

While there appears to be an obvious laziness factor involved here, the discussion boils down to whether philosophy can actually be used to know about the reality of things. Can we logically deduce what is good and bad to the point that it is a knowable objective truth?

Please feel free to provide an argument as to why you think this is or isn't possible and also discuss why you would or would not indulge the platonic theory of Forms.

[CRH99]

As proven by Plato in his dialogue "Euthyphro," we never really can tell what is right or wrong or good and bad. As far as I can tell, the theory of forms is based completely on perception, and therefore impossible to prove wrong or correct, however that does not defeat the purpose of discussion, it may serve little as far as a debate topic, but can be studied.

[Bleid]

In logic we have two separate concepts regarding arguments.

One concept is logical validity, which has to do with whether or not an argument is valid. For an argument to be valid, it must be the case that the conditional is met:

If the premises of the argument are true, then the conclusion is necessarily true.

The other concept is logical soundness, which has to do with whether or not an argument is sound. For an argument to be sound, it must be the case that:

1) The argument is logically valid.
and
2) The argument has all true premises.

When learning logic out of a book, someone might notice that the author only ever goes over how to determine logical validity and neglects logical soundness. The reason for this is, we can rigorously prove whether an argument is valid or invalid by a matter of deduction (whether the form of its reasoning is good or bad) but we leave it up to people and their own terms as to whether or not the arguments are to be considered logically sound because there is no fool proof way to rigorously determine that the premises are true through simple deduction (unless we already know for a fact that some of them are true prior to deduction).