A complete description of the argument and it's common variants can be found an IronChariots.org.
Briefly, the argument seeks to establish the existence of transcendental (or absolute) logical concepts, and then to argue that such transcendental concepts necessitate a transcendental mind (or god). The TAG argument is one of the many attempts to prove that god is a logical requirement of the universe.
- There are logical absolutes
- Law of identity
- Law of non-contradictions
- Law of excluded middle
- These logical absolutes are true, always
- These logical absolutes are transcendental, that is, independent of and not contingent on, space, time or matter
- These logical absolutes are concepts
- Concepts require a mind
- In order to be true always there must be a mind always to conceive them.
By writing my thoughts on this I am probably fighting far over my weight but the flaw in the argument is actually quite simple, and it all springs from a simple question.
Does the world obey logic, or does logic describe the world?Maps do not determine the terrain, they only describe it.
What we call "laws" of logic are descriptions, explanations, concepts of the fundamental nature of reality. But they are not the nature of reality themselves. We assume they are naturally emergent when a mind capable of abstract thought considers reality, which is a fancy way of saying that people should be able to come up with them without being told, just by thinking about it (and more than one philosopher has done exactly that in the long run of history).
The laws of logic are the same as any law of nature, in that they represents reality but do not cause it. We say they are "absolute" not because they are totally true, but because we have abstracted them from all subjective elements to produce an "absolute" or "pure" form of the observed behaviour.
It's a bit like the old question "If a tree falls in the forest and nobody hears it, does it make a sound?" in a strict scientific sense the answer is "no" because sound is defined as vibrations perceived by the act of hearing. The question however was originally meant simply to illustrate "unperceived existence" and personal perception of the universe - Does it exist for me if I cannot perceive it?
But reality is the state of things actually existing independent of perception or conception - Reality is that which persists when you stop believing in (or perceive) it. It is the shared context in which we all exist, that which is the same for each of us (Note: that is not the same as saying "that which we all agree on".)
Reality therefore and it's nature comes before any concept used to understand, describe, predict, define, or encompass it.
Logical absolutes (concepts) are true, always, because they attempt to describe other things (properties of existence), that are true always. An excellent example of how heated the TAG discussion can ge can be seen here. (many thanks to Atheist Community of Austin for an awesome and informative show)
The entire argument from the theists side relies on semantics to allow a fallacy of equivocation to slip thought the gaps. Basically because there is no clear distinction made between the logical laws and qualities of consistent reality they are attempting to describe, theists then proceed to ascribe the qualities of each to the other, concepts become transcendental properties of reality, and properties of reality now need a mind to contain them.
This kind of confusion is really only possible/easy with logical absolutes because they have been reduced to the simplest possible conceptual truths. If TAG were tried using the concept of gravity, it could easily be pointed out that the details of our concept of gravity change as we learn and observe more, while the actual behaviours we describe remain consistent, separating the two.
The concept and the actual effect are obviously two different things, but logical absolutes are a distillation of other concepts, a reduction down to that which can be considered safely immutable. For them, the simple, enlightening contrast between the idea and the reality is not so evident.
At best the transcendental argument for god is simply flawed reasoning, a failure to critically examine an argument that supports your theory. At worst TAG is a logical slight of hand used to give false hope to people questioning their faith and cast doubt in the minds of others. In either case it not useful as a proof for the existence of anything but the need for better arguments.