evil = not like flint, good = like flint...

Okay, then I'm going to protest this question because there's no such thing as a human with which this is testable.

Determining whether a human is "inherently good" or "inherently evil" is asking whether or not a person, without the influence of outside forces, would independently choose good or evil actions.  However, whether by laws, social stigma, or teachings of morality, those influences are a constant.  Even if you assume someone who's living in the jungle, that person will be shaped by their parental heritages.

So what if we pretended a person didn't have that parental heritage to fall back on?  That person wouldn't survive, and thus you have no test case.  Unlike reptiles, mammals require the link to their parents in order to survive.

In short, this is sort of like asking what's outside the universe.  Even if there's a discussion to be had, it's not one that any of us are educated enough to engage in because the circumstances required for it to be a legitimate thing are beyond observation.

man is good, some of his ideas are evil

I know the difference

if you don'tknow, you should probably do what I tell you

And fool this is more a poll to see the results, not planning a trap here.

Well, a definition for "evil" was provided, and I asked that for a specific purpose.  His definition of "evil" is better understood as behavior which is fundamentally in conflict with most organized societies.

Which in itself should be evidence that at least his definition of "evil" is not something inherently existing (i.e., why would every act which encompasses "evil" also be acts which are inherently harmful to organized society, unless the definition of evil was inherently an endorsement of organized society, something which fundamentally is entirely artificial).

There are three perspectives:

1) that there is objective morality / truth (one cannot hold there is objective morality without holding that there is also objective truth).

2) that there is only subjective morality / truth (whatever is good or true to you / society is the only goodness or truth there is).

3) that there is neither objective or subjective morality nor subjective or objective truth, and, rather, only amorality and observation.

Arguments that are often put forth to substantiate or prove one or the other of the above perspectives inevitably result in contradictions, leaving the only rational conclusion that we are unable to reconcile the issue in any definitive manner.  As a result, I see any discussion on the matter as vain - moot points after moot points. 

It is simply not useful to discuss good vs. evil in the traditional sense but rather consider "good for" and "bad for" instead. And so instead of asking "is man normally bent to evil but society keeps man in check, or is man good [but society corrupts him]?" we might find it more useful to rephrase the question and ask:

Are human beings inclined to do that which is 'bad for' them, or are human beings inclined to do that which is good for them?

If human beings are inclined to do that is good for them, how can we account for all the detrimental impacts human beings have had on themselves and the world?

In our complex society, as individuals and as humanity as a whole, are we even capable of determining what is 'good for' us?  How would we define that which is good for us?  Our survival as a species, perhaps? 

One could argue that the survival of the human species might be 'evil', for instance, by arguing that it might be objectively immoral of us to survive if in fact our survival might come at the expense of the extinction of other species. But could they argue that the survival of the human species isn't 'good for' the human species? 

I personally think the basis for a system of 'morality' that all people everywhere might be able to accept would probably be derived by an analysis of what is good for us as a species - what will help us survive and thrive as a species would be 'good', although, because system of morality would be based on our survival regardless of whether or not our survival would be moral or immoral, such a system of morality would be essentially based on an amoral perspective.

im·mor·al
[ih-mawr-uhl, ih-mor-] Show IPA
adjective
1.
violating moral principles; not conforming to the patterns of conduct usually accepted or established as consistent with principles of personal and social ethics.
2.
licentious or lascivious.

mor·al
[mawr-uhl, mor-] Show IPA
adjective
1.
of, pertaining to, or concerned with the principles or rules of right conduct or the distinction between right and wrong; ethical: moral attitudes.
2.
expressing or conveying truths or counsel as to right conduct, as a speaker or a literary work.
3.
founded on the fundamental principles of right conduct rather than on legalities, enactment, or custom: moral obligations.
4.
capable of conforming to the rules of right conduct: a moral being.
5.
conforming to the rules of right conduct (opposed to immoral ): a moral man.

a·mor·al
[ey-mawr-uhl, a-mawr-, ey-mor-, a-mor-] Show IPA
adjective
1.
not involving questions of right or wrong; without moral quality; neither moral nor immoral.
2.
having no moral standards, restraints, or principles; unaware of or indifferent to questions of right or wrong: a completely amoral person.

'Morality' exists, but in many forms as discussed above, resulting in dysfunctional society, the solution for which might be to form a system of morality based on, as you term it, utilitarian calculus, or what is essentially "good for" or "bad for" us as individuals, a civilization, and as a species.

tell me about your parents...

Simple answer to a simple question: Self interest.

Would you like elaboration?  Of course!

We will start on why we can replace the word evil with self interest.  Why do you do a bad thing? Do you need food, water, and shelter?  Are envy, greed, and jealousy behind the motives?  Did you brain make some strange pleasure associations as a child so you enjoy doing things that disrupt social norms?  Are you caught in a mob mentality state with crowds of people acting under a mix of the above motives?
Same goes with good.  It in some way benefits you, financially, morally, or socially.
I rest my case.