Connie Du Toit has penned (OK, typed) a beautifully introspective examination regarding how we comparatively hairless apes arrive at a determination of ethical behavior, see here:
On the purely individual scale, I suspect she is far more right than not about our individual decision-making process. In fact, I would go so far as to say that for most people, most of the time and for most subjects, there isn't any deep consideration of the particulars of a given instance; they "know" right from wrong and consider that to be ethical. When they were children, living in Mommy and Daddy's house, that was even largely true.
Out here in the lonely and more than a little frightening grown-up world, that simply won't do.
We know that there aren't any monsters under the bed because we aren't afraid to look. Similarly, we know that much of what we term "progress" has aspects that are disturbing at best and quite often outright dangerous to our continued existence. That does not inhibit us from continuing to look, however, and for very good reason.
Two of them, actually; self defense and societal consensus. Since the first isn't especially germane to this discussion, I will leap ahead and ask, how does a society arrive at an ethical consensus?
Mostly by inheritance, I know; "It was good enough for Gramps and Dad, it's good enough for me." may in fact offer an acceptable result. In other applications of this same process we call this legal or medical precedent, for example. This is not, I suggest, a particularly deliberative process though. It offers little in the way of direct applicability to an innovative concept and, I would argue even worse, it actively prohibits measured consideration of an idea or process on it's own merits.
A really simple (and probably simplistic) example can be drawn - pardon the pun - from the question, "Is water good for us?" Without allowing myself to be diverted into the details of the question itself, the illustration it provides is that there is only one way we can come to any sort of considered conclusion, through research. In the end, there's only one way to be really sure just how much, and of what quality, water is not good for you. With predictably unfortunate - and ethically questionable - results for at least some of the experimentees.
If your response to that circumstance is some variation of, "The ethical ramifications of such research could lead to some really horrible conclusion", the more intelligent response is to say, "Thank you, do remind us when you think we're getting too close to that. We don't want to go there either, but we aren't going to let our fear defeat our understanding". Such conversations are the mechanism we employ to arrive at a societal consensus, which is nothing more than a condition of existence with which we are prepared to cope in order to have a society at all.
Human history is chock full of really bad things we've learned to make and taught ourselves to do to each other. Human history is equally full of stories of human triumph over adversity and optimism about our eventual state of being. I see little hope for the future being anything other than more of the same in somewhat different and interesting conditions, sad to say. And that's actually a good thing.
The bing fa, the philosophy of strategic science, teaches that a "problem" is defined by the boundaries of it's limitations. Consequently, the good strategist uses this condition to expand the strategic field beyond those limiting factors, thereby converting a problem, something that distracts from or works against one's position, into an asset that can be used to advance one's position. In other words, don't confine your thoughts only to the problem, expand your range of consideration to include it's successful resolution.
That is ethical behavior.