interesting video, but I think that Kreeft attacks a straw man.
First of all, in order for Kreeft to be guilty of a straw man fallacy, he has to provide a refutation to an argument that atheists are not actually making. In the video Kreeft admits that there are a variety of sources that atheists consider to be the basis of morality, of which he has elected to address five. Therefore he admits that his presentation is not all-inclusive (and understandably so, seeing as the whole thing is less than six minutes long). In terms of the ones he chose to address, a few simple Google searches show that such discussions about morality do exist out there, and therefore there is no straw man fallacy being committed.
I agree, athiests have no reason to believe in an unchanging, objective code of morality, but in my little experience with atheists, few actually take this approach. Most that I’ve come across prefer to use utilitarianism or the idea of an evolved conscience… and accept the full consequenses of either appoach.
Both the evolution-only and the utilitarian-only theories of morality are addressed in the video. So if most of the atheists you’ve encountered resort to an evolution or utilitarian explanation of morality, and Kreeft addressed them both, then why do you believe that Kreeft “attacks a straw man”?
Moreover, I think it is important to point out that Kreeft does not actually
prove that evolution and utilitarianism
cannot provide a system for morality (nor does he promise to), but only demonstrates the ramifications of accepting such theories. In my opinion, Kreeft’s video is a “food for thought” presentation based on the modern common ground perception that certain things, such as slavery and the Nazi war crimes of WWII, are considered to be evil and never acceptable. The “food for thought” aspect is whether or not a person thinks that the ramifications of certain proposed theories of morality are truly in keeping with what seems to be an innate sense of morality shared by the vast majority of people. If someone wants to, as you say, “accept the full consequences of either approach” then Kreeft is pointing out that those full consequences includes not being able to call slavery and Nazi war crimes universally evil, despite the fact that the vast majority of people consider them evil, morally repugnant and never acceptable.
Those who take the approach of the evolved conscience typically do agree that morality does and must evolve over time, and those who operate under utilitarianism would say that if you could actually increase the overall happiness of a nation by adopting slavery, then it would be morally obligatory to adopt slavery. Of course, most know that this possibility is rediculous.
But how does an evolution-only or utilitarian-only theory of morality allow someone to believe that the possibility of slavery being considered moral in the future is “ridiculous”? To make that prediction, they have to step outside of these systems of morality and appeal to another standard of morality.
The other approach atheists seem to take is that of moral relativism, and the belief that there is no standard of morality at all.
I have yet to see such a concept proposed. In my experience with interacting with atheists, they all accept the idea of a moral code (or at least live their lives as if they do). What is debated is the source of the moral code, what is involved when a human makes a moral decision or a moral judgment, and how extensive a particular standard of morality is.