The reason I said that he does not know how to research is because the current scientific method was for a large part designed by Popper.
[I][B]1[/B][/I]. [URL="http://en.wikipedia.org/wiki/Scientific_method#Characterizations"][COLOR=#800080]Use your experience[/COLOR][/URL]: Consider the problem and try to make sense of it. Look for previous explanations. If this is a new problem to you, then move to step [I][B]2[/B][/I].
[I][B]2[/B][/I]. [URL="http://en.wikipedia.org/wiki/Scientific_method#Hypothesis_development"][COLOR=#800080]Form a conjecture[/COLOR][/URL]: When nothing else is yet known, try to state an explanation, to someone else, or to your notebook.
[I][B]3[/B][/I]. [URL="http://en.wikipedia.org/wiki/Scientific_method#Predictions_from_the_hypothesis"][COLOR=#800080]Deduce a prediction from that explanation[/COLOR][/URL]: If you assume [I][B]2[/B][/I] is true, what consequences follow?
[I][B]4[/B][/I]. [URL="http://en.wikipedia.org/wiki/Scientific_method#Experiments"][COLOR=#800080]Test[/COLOR][/URL] : Look for the opposite of each consequence in order to disprove [I][B]2[/B][/I]. It is a logical error to seek [I][B]3[/B][/I] directly as proof of [I][B]2[/B][/I]. This error is called [I][URL="http://en.wikipedia.org/wiki/Affirming_the_consequent"][COLOR=#0000ff]affirming the consequent[/COLOR][/URL][/I].
This model does not take into account ontological differences though. The model only works in an empirical world-model (which does not allow for creation, ontological differences). Therefore the model does not survive itself because it creates paradoxes, refuting the outcome of research results.
If oyu did not get the casts-system from Aristotle's work, then please read them again. Aristotle is a very nasty person once you see what he speaks about. I'd say that the thought-objects causing problems in the world today are directly related to Aristotelianism, but who am I?
Plato does something else and I would like to note that the people arguing for free societies during the enlightenment were Platonists.
Concerning and slavery new topics might be needed. I, for one, like to state that in no situation slavery is ever 'good'. It is merely something that was accepted because people did not know how to resist it. There were other ideas around though, like Plato's or perhaps the slaves had some ideas concerning that...
As you say, slavery was accepted. No man could be made a slave against his will, his consent. There is even an element of democracy involved, because the owners of slaves were no less slaves than the slaves and each ate off the same soil. It is not good, only better than no relationship, as canibolism was, or killing prisoners. Judged against what it did to the larger society, on the one hand freeing some people to thought, and making slaves of the population forced to compete with slaves, it was not good, but a positive evil. Philosophers are never in the right position to judge their own societies, even if they can refine our methods at arriving at truth.
And, your statement about the enlightenment strikes me as strange since it is Metaphysical and Christian values that most resulted in it. I don't know what Aristotle called his metaphysics, but I do know it was not called metaphysics. And yet metaphysics, and St. Paul stand behind the Declaration of Independence which is one of the finest fruits of the enlightenment. All men are created equal. Nice thought. No one believes it, and Nietzsche was right to abuse Paul over it. People are not created at all. We are equal, genetically equal, inbred to a brittle and dangerous degree, but we are not created at all, equal or otherwise. And so far as I know, PLato had no metaphysics as such. I'll have to look in my Windelband to see what he has to say.
And I agree that the method proposed by Popper has its faults. I would say the weakness is general, but specifically between three and four. If you are in error about a consequence, that does not imply that its opposite is right. If you say the further off from England the nearer is to France; it is only true in a very particular sense, and generally false, but to state the opposite conclusion gets us no nearer the truth. Only in a dictionary is truth the opposite of false. Just as with the world, anywhere not north is the opposite of north, if taken from a single point, and from that point every direction is south, which is retarded to say too, that every point is south, when south is not a point usually, but a direction. Yet, we are used to looking at life in opposition, so we say hate is the opposite of love. It is not. Not love is the opposite of love. Does that make sense to you.