Here's my three-word rebuttal to Hume's is-ought gap: "Get over yourself."
A lot of people seem to think that not having ethics that are sourced outside ourselves is a problem, and that it requires a well-thought-out solution. This is not the case. It has become increasingly obvious that our ethical sense is built on the bedrock of biology and natural selection, and that guilt, compassion, fear, and anger, emotions commonly associated with being ethical, are instincts dictated by biology. Therefore what we value and who we are are one and the same. After all, when debating someone, you don't ever tell them to abandon their values, but merely to examine their values in light of the evidence. To simultaneously abandon every single value you have would destroy you as a person. It's more than can be asked of any person. Simply put, ought is what we value. It's as simple as that.
But, critics contend, doesn't that make right and wrong arbitrary? How can we say that slavery was truly wrong, for example, if it's just our perspective? What they don't realize is that this is a non-sequitur. Since we lack trust in our perspective, and are so capable of abstract thought, we are used to regarding some sort of external source of morality as necessary in order to give it credence. Just because morality is based in our heads doesn't make it arbitrary. Since our values are in some way determined by biology, the goal of ethics is to better understand those values and attempt to better live within them.
Of course, we do have an external source of morality. We naturally alter our behavior in light of things around us, most especially our fellow human beings. Thus, what arises is something between a universally applicable standard and an internally defined standard: a common standard. A standard that is shared amongst human beings is not arbitrary. It is shaped by natural and social selection, and has been since life first began.
Our morality is, of course, imperfect, but you don't have to peruse through the ethical debates of the day to not know that already. We naturally seek out ways to improve our ethic, using reason and our interactions with our environment. But our ethical standard is ultimately bound up with who we are as human beings, and the instincts we share. That brings up a litany of questions, and I hope to address those in future blogs, but I think that gives us enough to go on for now.