Francis Schaeffer is probably the single apologist who has most shaped how I approach arguments from non-Christian worldviews. One of the things he often said was that it is impossible to arrive at a universal when you begin with a particular. That of course sounds rather vague but what Schaeffer was getting at was this: when you begin with autonomous man (man apart from God) and his reason you can never arrive at concepts that are universally applicable, things like objective ethics, laws of logic, uniformed laws of nature etc. These concepts are universals (apply in all places at all times) and they simply can not be reached logically when you begin with man and his autonomous reason.
This is the dilemma of all thought that begins divorced from God and His self revelation in the Bible. All thought starts with man the particular and can not break free from that subjectivity. This is where we are today as a culture as we hear of the various "culture wars" and different groups trying to impose their morality through law. It is tragic because I think so many of the moral "victories" through legislation are really hollow and speak more of the decadence then of the hope for the culture still maintaining it's integrity. I just think about how states are voting on whether same sex couples should be allowed to marry. Many consider the outcomes which almost unanimously support (I wanted to say "traditional" but that is part of the word games going on as if non-traditional is an equal option) marriage. Many hail these as victories I can't help but see them as defeats dressed up in the victors garb. The mere fact that we as a society have lost our moral compass to such a degree that we now will VOTE and decide for ourselves what will be "moral" speaks of the degree of autonomy and thus lostness of our culture.
The above paragraph is all a side note for what I am really trying to get at in this post and is really a picture of the effects of trying to base ethics off of autonomous man. The effect is moral relativism. What I want to really display here is the statement of Schaeffer in the area of ethics. In an earlier post I responded to an Atheist who was attempting to give reasons for his acting morally in the universe. If you read the dialogue (scroll down or click here) you will see him offer one reason for acting morally after another only to have each reason challenged with the question "Why is that the standard?".
This is the problem of beginning with particulars and trying to arrive at a universal (in this case a moral ought or obligation). Each reason or argument is itself a particular and thus falls short of universal application and thus makes it impossible for a objective moral ought to exist when you begin with man philosophically. This is what the problem looks like in a more formalized fashion:
Autonomous: Morality is based on that which will bring the most happiness to the most people (Argument A)
Skeptic: Why should I care about anybody elses happiness?
Aut: You should care about the happiness of others because you should treat others the way you want to be treated. (Arg B in support of A)
Skep: Why should I engage treating others the way I happen to like to be treated?
Auto: When we do that (B) it encourages the greater good of society. (Argument C in support of B in support of A)
Skep: Why should I care about the "good of society" and others in society?
Auto: You should care about the good of society (C) for the future of humanity. (Argument D in support of C in support of B in support of A)
Skep: Why should I care about D?
This sort of discussion will go on ad infinitum because all Mr.Autonomous can do is point to another particular to try and support another particular and then he will need to point to another particular to support the one he just brought up and so on. He will never make a statement where he can say: "The buck stops here! This is the absolute and final standard, you can not ask 'Why?' to this."
This same sort of issue applies to all forms of universals, morality just happens to be my favorite one to bring up. I could equally point to the uniformity of nature and how modern science when run autonomously from God and His revelation has no reason to believe in the uniformity of nature (that the future will resemble the past) it is simply irrationally assumed. This is to philosophically build without a foundation, the ideas are just kind of floating like a house without a foundation.
My final and concluding point is that to arrive at a universal you must start with a universal. A universal to clarify would be a reference point outside of the particulars within system to which particulars can point to as a standard. The Christian God fits this bill perfectly. With the Christian God we have an objective standard of ethics, secularists and atheists might not like the Biblical standard but that doesn't change it's objectivity. It is objective because it's reference point is God who is outside of the universe of particulars being the creator of that very universe. He gives a rational basis on which science can proceed, being that nature is uniform because He has created it's laws and holds it together thus we have reason to suppose a regularity rather then a blind leap as science divorced from theism must make in this foundational area.
I could really go on with other areas but again my main point in this post was to get at what I laid out above, which is simply this: When you begin with autonomous man as a particular you can never arrive at a universal. I think this is important especially for us as Christians to note. Because what it ultimately means is that though the God rejector may use moral language and even share similar ethical values as us he in reality is still miles apart. Ultimately the unbeliever is living as Van Til said on borrowed capital, they go through moral motions and believe them to be meaningful but having divorced these motions from God these actions are really foundationless and thus irrational (mere existential leaps) and meaningless.