The transcendental argument for the existence of God (TAG) attempts to show that logic, science, ethics and generally every fact of human experience and knowledge are not meaningful apart from a preconditioning belief in the existence of God. Since logic "exists", then so must God. The basic form of the argument was developed by Immanuel Kant which he used to attack skepticism and idealism rather than to argue for theism. 
"The transcendental proof for God's existence is that without Him it is impossible to prove anything. The atheist world view is irrational and cannot consistently provide the preconditions of intelligible experience, science, logic, or morality."
The philosophical study of knowledge, known as epistemology, features many thorny and unresolved conundrums, such as the Münchhausen trilemma. This is particularly true in ancient philosophy, such as Platonic idealism. Apologists claim that there must be a solution because "knowledge" is seemingly possible and that God somehow provides a solution. For presuppositional Christian apologists, rejecting this reasoning is tantamount to a rejection of all knowledge: supposedly atheists cannot know anything. A similar argument is the conceptualist argument which is based on the existence of true/false facts or propositions being the effect of a mind.
- "That’s why TAG is a good argument—not that it’s accurate but that it’s confusing. "
Is knowledge is possible?
- Main Article: Absolute certainty
Generally speaking, all theistic transcendental arguments use the axiom that knowledge is possible or an equivalent statement such as "The Laws of Logic form the basis of rational discourse"  or "human communication is possible".
What the apologist doesn't make clear is they assume some version of Platonic epistemology in which knowledge is "justified true belief". This should be understood in the sense that knowledge can never be mistaken, in that it is absolute.
- "I affirm that we discover the logical absolutes. This must mean that we discover what already exists. "
The apologist also often implicitly assumes that knowledge of abstract ideas is innate and that knowledge of these abstract ideas is absolute.
The question is: is such knowledge, according to the definition implicitly used by apologists, even possible? Without this axiom being supported, the transcendental argument collapses. Since the arguments that support the possibility of this type of knowledge are weak, this axiom may be a case of wishful thinking.
This argument is similar to the ontological argument. Just because you semantically define something "transcendent and perfect" doesn't mean it actually exists.
A posteriori knowledge, as defined in this argument, is unattainable
Skepticism provides many strong arguments against certain a posteriori knowledge, such as René Descartes's evil genius. Many non-theists, when they are backed against the wall, will admit that they know nothing with 100% certainty. Psychologically, humans generally will prefer some explanation rather than no explanation. However, providing "some explanation" does not make the claims in the explanation true. Absolute certainty is in general meaningless as by definition one would have to be omniscient to acquire it. Atheists do not in general make claims to the absolute truth of things; this is usually the domain of the theist.
An example of what some may call absolutely certain is the idea that the Sun will rise tomorrow. To be truly absolute in certainty, you would require precognition; however, that is generally useless. It's much more accurate to state that inductively based on the evidence of many days prior as well as our understanding of chemistry and the composition of stars that the sun will not soon cease to rise.
Is synthetic a priori knowledge possible?
- "Thankfully, two plus two does equal four. There is absolute truth, and it can be found and understood. "
Philosophers have long debated if synthetic a priori knowledge is possible. This includes fields such as logic, geometric and mathematics. Immanuel Kant argued that this was indeed a priori knowledge. David Hume later argued that some concepts which seemed to be a priori were actually a posteriori, such as cause and effect. Since logic and geometric are branches of mathematics, this argument is a form of argument from mathematical realism. However, it may be there are in infinite number of mathematical axioms that exist a priori and we have selected a useful subset a posteriori.
Mathematics appears to have the property of being a priori and at the same time reflecting physical reality - this seems to set them apart as "knowledge" and not just an arbitrary set of axioms. There is no certainty that reality might not change tomorrow to a completely different set of mathematical and physical laws. For this reason, even mathematics is not absolute knowledge.
- "Our nature is as much a fact of the existing world as anything, and there can be no certainty that it will remain constant. It might happen, if Kant is right, that to-morrow our nature would so change as to make two and two become five. "
By forced choice
- "There either is absolute truth, something that is true at all times and places, or there is not. To argue with certainty that there is no such thing as absolute truth is to make an absolute truth claim, and is thus self-refuting. Therefore, the only option remaining is that absolute truth does exist. "
- "A good question to ask people who say, “There is no absolute truth” is this: “Are you absolutely sure of that?” If they say “yes,” they have made an absolute statement—which itself implies the existence of absolutes. They are saying that the very fact there is no absolute truth is the one and only absolute truth. "
This is probably the most popular argument used by apologists to support absolute truth. However, it is rarely used by expert apologists because it contains a serious false dichotomy. When considering the propositon "absolute truth exists", there are three positions we can have:
- We know it to be true
- We know it to be untrue (which is arguably a self-contradiction)
- We cannot say if it is true or untrue (which is the option missing from the above arguments)
We cannot rule out the second choice and then conclude the first choice is true, particularly when the third option is actually the case.
If absolute truth does not exist, the claim "Absolute truth does not exist" is not absolutely true either. As the above sentence - in its entirety, so all that is italicized - must be true, it forms the proof of the existence of absolute truth. 
Just because we cannot say absolutely that absolute truth does not exist, it does not follow that it does exist. We simply cannot confirm if it does or does not exist. This is therefore an argument from ignorance and an attempt to shift the burden of proof.
Defining something, in this case "absolute truth", so that it must exist is a proof by logic and not appropriate for determining how reality actually is.
- Main Article: Argument from personal experience
- "Another problem with the denial of absolute truth/universal truth is that it fails to live up to what we know to be true in our own consciences, our own experiences, and what we see in the real world. If there is no such thing as absolute truth, then there is nothing ultimately right or wrong about anything. [...] Is there any evidence for the existence of absolute truth? Yes. First, there is the human conscience, that certain “something” within us that tells us the world should be a certain way, that some things are right and some are wrong. "
- Main Article: Moral argument
- "People would be free to do whatever they want—murder, rape, steal, lie, cheat, etc., and no one could say those things would be wrong. There could be no government, no laws, and no justice, because one could not even say that the majority of the people have the right to make and enforce standards upon the minority."
From natural law
- Main Article: Natural-law argument
- "Without absolutes, what would there be to study? How could one know that the findings of science are real? In fact, the very laws of science are founded on the existence of absolute truth."
This is a separate issue called the natural-law argument.
- Main Article: Argument from scripture
- "Fortunately, there is such a Creator, and He has revealed His truth to us through His Word, the Bible. Knowing absolute truth/universal truth is only possible through a personal relationship with the One who claims to be the Truth—Jesus Christ."
Presuppositional apologetics arbitrarily assumes a particular Bible or a particular interpretation of God. However, this is an unjustified assumption. In the context of this argument, any other concept or book is seemingly as valid as the Bible. Any god or gods could be justified using arguments of this type.
One common move out of this is to defer to divine revelation. This tactic abandons presuppositional apologetics entirely because it uses the Bible or God is axiomatic.
Of course, using scripture to show knowledge exists makes the rest of the argument circular.
Revelation supports the Bible
One of the major omission of presuppositional apologetics is that it does not explained how a single holy book or divine entity can provide the necessary basis for justify reason, knowledge or logic. At least some other presuppositions are required to make these intelligible.
Some apologists claim that presuppositionalism is supported by divine revelation. This destroys their own argument that Christian presuppositionalism requires no other justification. It also relies on logic to support presuppositionalism, which Van Tillian apologetics says is less fundamental than their presuppositional axiom (God or the Bible).
"I submit that you can't know what is ultimately real without revelation from God. How do I know what is real? The same way that all of you do. Revelation from the God that all of you know exists."
- — Sye Ten Bruggencate 
The argument is therefore abandoned by the apologist as they resort to the argument from personal experience.
- Main Article: Appeal to consequences
Apologists argue that without their theistic justification for truth, "there is no proof of anything". Fortunately, people can and do live without absolute certainty - sometimes by fooling themselves into the belief it exists.
Another appeal to consequences is to claim that the lack of absolutes would lead to anarchy.
- "That would mean that everybody does what they think is right--setting their own rules for life. The problem comes when one person's rules clash with another's. What if one person decides that killing is a noble thing to do, and so attempts to kill everyone in sight? "
This is not really an objection because it describes the actual world - some people commit murder and other people decide to arrest and imprison the murderer. They don't need to reach agreement on morality or "respect each others views" to take actions based on their beliefs.
Versions of TAG
Knowledge depends on God
That is, knowledge cannot be obtained absolutely unless the source of that knowledge is itself an absolute source (read: being/God). Therefore, either you subconsciously believe in an absolute being that upholds and makes absolute the laws of the universe/morality or you do not—and can not—know anything for certain.
"The best, the only, the absolutely certain proof of the truth of Christianity is that unless its truth be presupposed there is no proof of anything. Christianity is proved as being the very foundation of the idea of proof itself. [...] It is the firm conviction of every epistemologically self-conscious Christian that no human being can utter a single syllable, whether in negation or affirmation, unless it were for God’s existence."
- "in order to affirm rationality and logical thinking, there needs to be some ground of this in God rather than in the evolutionary process because the evolutionary process doesn't aim at truth. It merely aims at survival. "
"Thus I see plainly that the certainty and truth of all knowledge depends uniquely on my awareness of the true God, to such an extent that I was incapable of perfect knowledge about anything else until I became aware of him."
- "[...] we have Locke's word that acceptance of a divinely ruled and rational universe is a necessary precondition for knowledge. "
"When you are arguing against Him, you are arguing against the very power that makes you able to argue at all: it is like cutting off the branch you are sitting on."
There are many variant wordings of the argument. The argument is classically stated as:
(1) If God did not exist, rational thought would not be possible.
(2) Rational thought is possible.
(3) Therefore, God exists. 
Based on the way the argument is actually employed, a more complete version would be:
- Epistemological problem X exists. (such as the existence of rational thought or the foundation of logic)
- Without God there is no solution to X.
- God is a possible solution to X.
- X must have a solution (either theism or not theism).
- If God did not exist, X is not explainable.
- Therefore God exists.
Logical absolutes depends on God
Other iterations of the same general theme exist.
- "But why do the laws of logic hold? For the Christian, there is a transcendent standard for reasoning. As the laws of logic are reduced to being materialistic entities, they cease to possess their law-like character. But the laws of logic are not comprised of matter; they apply universally and at all times. The laws of logic are contingent upon God’s unchanging nature and are necessary for deductive reasoning. The invariability, sovereignty, transcendence, and immateriality of God are the foundation for the laws of logic. Thus, rational reasoning would be impossible without the biblical God. "
- "since The Laws of Logic are always true everywhere and not dependent upon human minds, it must be an absolute transcendent mind that is authoring them. "
- The logical absolutes are rational, transcendent and not material.
- Atheism presupposes that everything comes from material sources.
- Therefore, atheism lacks any objective source for logic.
- The logical absolutes are based on either theism or atheism (materialism).
- Since atheism is refuted, theism must be true.
- God exists.
Treating the logic absolutes as existent things is rather like the natural-law argument.
Arguments to support "knowledge depends on God"
Evolutionary processes do not guarantee truth
- Main Article: Evolutionary argument against naturalism
Alvin Plantinga argued that metaphysical naturalism contains its own "defeater": if our beliefs are a result solely of natural processes such as evolution, then they are unreliable. Thus, the belief that only nature exists is itself suspect.
Argument from proper function
- Main Article: Argument from proper function
According to Alvin Plantinga, for knowledge to be possible, our cognitive faculties must be working according to a "good design plan". Otherwise, we could not rely on our knowledge. Since humans have knowledge, there must be a "good design plan" created by God. 
Argument from anti-realism
- Main Article: Argument from anti-realism
This argument is based on reaction to anti-realism in philosophy. Some philosophers argue for metaphysical realism, which is the idea that reality is the way it is regardless of what humans think about it. However, when humans go about trying to understand and describe the world, they necessarily make use of some system of "objects" and methods of formulating their theory. It is entirely possible these assumptions turn out to be false, since human thought does not necessarily reflect reality. This is a strong argument for global skepticism, which denies knowing anything is absolutely true or false. Alvin Plantinga argued we do have knowledge (and global skepticism is false) because God furnished people with faculties that lead to generally reliable knowledge. 
The one-many problem
According to Cornelius Van Til, Christian theology supposedly addresses the one and the many problem.  This metaphysical conundrum is difficult to express with any precision but relates to individuality, dissimilarity, oneness, plurality, absolutes and which is the ultimate form of reality. Since philosophers cannot agree on strict realism vs. strict nominalism, Christians refer to the trinity as providing an analogical middle road in that oneness and separateness are both "co-ultimate". Van Til claims that if either realism or nominalism were ultimate, knowledge would be impossible.
- "If it is their individuality, then the many are ultimate and the proper source of authority, and we have philosophical Nominalism. If it is their oneness, then the one is ultimate, and we have Realism. [...] Since both the one and the many are equally ultimate in God, it immediately becomes apparent that these two seemingly contradictory aspects of being do not cancel one another but are equally basic to the ontological trinity: one God, three persons."
It is questionable if an earthly confusion is "explained" by a similar theological confusion.
Unity of knowledge
Another argument of Cornelius Van Til is that for any knowledge to be possible, at least one mind must have comprehensive knowledge. Since knowledge is possible, a mind with comprehensive knowledge must exist. Therefore, God exists.
"This modern view is based on the assumption that man is the ultimate reference point in his own predication. When, therefore, man cannot know everything, it follows that nothing can be known. All things being related, all things must be exhaustively known or nothing can be known."
- — Cornelius Van Til
Solves the problem of induction
The problem of induction is the question of how we account for the uniformity of nature which is assumed in inductive reasoning. Scientists are usually content with taking this as axiomatic. Apologists demand a justification for this and cite God as the justification.
"Our argument as over against this would be that the existence of the God of Christian theism and the conception of his counsel as controlling all things in the universe is the only presupposition which can account for the uniformity of nature which the scientist needs."
- — Cornelius Van Til
It seems as if any classic problem of philosophy, such as the problem of other minds, is taken as proof of the existence of God.
Argument from conceptual schemes
According to Cornelius Van Til, knowledge is only possible if reality has some intelligible structure and human minds have a faculty to uncover this structure.
- "If God is left out of the picture it is up to the human mind to furnish the unity that must bind together the diversity of factual existence."
This is somewhat similar to Alvin Plantinga's "good design plan".
Arguments to support "logical absolutes depend on God"
Since logic is a branch of mathematics, these arguments are essentially variants of the argument from mathematical realism.
Logical absolutes are not material
- "The Laws of Logic are not dependent on the material world. [...] If they were properties of the universe, then they could be measured the same way heat, motion, mass, etc., are measured. Since they cannot be measured, they are not properties of the universe. [...] If they are conceptual by nature, then they are not dependent upon the physical universe for their existence. "
While logical absolutes may or may not be material, the way we obtain the concept in our mind is probably material. Real objects are generally found to be not in mutually contradictory states (although what an "object" is arguably requires some subjective interpretation). There are an infinite number of foundational logical axioms - the "laws" of logic may be simply an a posteriori selection that fits our material universe.
- "If The Laws of Logic were the product of human minds, they would cease to exist if people ceased to exist, which would mean they would be dependent on human minds."
The claim that logical absolutes would exist if the universe did not is an unfounded assertion. If the universe did not exist, the three logical absolutes as they would have nothing to apply to. If nothing existed there would be no A to equal A. The underpinning of the logical absolute statements are dependent on something existing. Matt Slick responded to this by writing:
- "How is my assertion unfounded when the refutation of it is itself an unfounded assertion? "
You could say that the applicability of the logical absolutes outside the universe, to an empty universe or to other universes is unknown. However, the burden of proof is on the apologist not the skeptic.
Matt Slick stated:
- "how do you observe the Law of Non-Contradiction (LNC, cited in the original argument at 1.B) which deals with truth statements? Or what about the Law of Excluded Middle (LEM, cited in the original argument at 1.C) which says that statements are either true or false? Statements are the products of minds! Statements aren't observed. How is LNC or LEM observed without presupposing their validity to begin with?"
Obviously conceptual statements of logic cannot be directly observed but their validity and usefulness are apparent in most or all observations. They are provisionally accepted, then trusted by induction. Of course induction relies on logic; that does not stop both logic and induction being provisionally accepted together and confirmed a posteriori on such a basis. However, it may be more accurate to say that these assumptions are woven into our language and "world view", based on our psychology and experiences.
Apologists sometimes use a dualistic argument:
- "Given that logical absolutes are by nature conceptual, how does the atheist account for their existence in the universe of nothing but matter and energy?  [...] How can an atheist logically claim that one chemical state in the brain which leads to another state necessitates proper logical inference? It seems quite unlikely and without proof of some sort saying that The Laws of Logic are abstractions of (human) minds doesn't account for them."
There is plenty of evidence in neuroscience that thought is a function of the material brain. Demanding proof of a scientific explanation but falling back on theism in the mean time shows this argument is an argument from ignorance and god of the gaps (and shifts the burden of proof). Also, science does not deal in "proof" but in theories and evidence; the apologist is asking for an unreasonable standard from their critics. Dualism also raises its own philosophical problems.
Logical absolutes are transcendent
- Main Article: Argument from mathematical realism
Many but not all philosophers consider the laws of logic to be transcendent.
- "The Laws of Logic are transcendent. The Laws of Logic are not dependent on space. [...] The Laws of Logic are not dependent on time. [...] The Laws of Logic are not dependent on people. That is, they are not the product of human thinking. [...] The Laws of Logic are not the product of the physical universe since that would mean they were contingent on atoms, motion, heat, etc., and that their nature was dependent on physical existence."
The individual laws are among an infinite number of possible a priori mathematical axioms. The useful ones were found a posteriori by convention. So they are in a limited sense transcendent but the particular laws are dependent on a human view point in this universe. To claim our laws of logic and broadly transcendent is to commit the spotlight fallacy: perhaps over universes have very different "laws".
How does the apologist know logic does not vary over space and time?
Apologists sometimes argue that the logical absolutes are transcendent (in this case meaning "non-contingent") of space, time and matter. They also seem to be non-contingent of thought as well but the apologist left that one out because it would refute their argument.
- "But, if the universe did not exist, The Laws of Logic are still true. "
Has the apologist observed this directly from outside the universe? Of course, this is an unsupported assumption.
- "You have recognized that they are widely used, but they are because they are transcendent. They do not become transcendent because they are widely used."
This is begging the question that they are indeed transcendental. The apologist needs to distinguish between these two possibilities.
Logical absolutes are absolute and not subjective
- "The Laws of Logic are absolutely true. [...] People's minds are different. What one person considers to be absolute may not be what another considers to be absolute. People often contradict each other. Therefore, The Laws of Logic cannot be the product of human, contradictory minds. "
- "The street is either filled with cars or it is not. It is either safe to cross or it is not. BOTH realities cannot exist at the same time. One truth must exist at the exclusion of the other. "
Not everyone agrees that logic is objective or absolute. There are various alternative systems of logic, collectively called non-classical logic. People temporarily assume that logic is absolute for the sake of their argument. That assumption does not make it absolute in reality. The particular choice of logic system they adopt is a subjective choice. The way experiences are interpreted into objects in order that logical may be applied is subjective.
Someone claiming that an object cannot be A and not-A at the same time, which is indeed a law of logic, shows they have a lack of understanding of quantum mechanics. It is quite common for things to be an different mutually-exclusive states simultaneously, such as Schrödinger's cat, or even in two different places at once, as in the double-slit experiment. Attributes such as alive/dead, inside/outside are often not mutually exclusive. This shows that logic does not always reflect reality and is therefore not absolute. In other words, can be be absolutely sure the law of non-contradiction is applicable in a particular physical situation which may be subject to quantum effects?
Logical absolutes reflect its creator
- Main Article: Argument from design
- "Since the The Laws of Logic are transcendent, absolute, are perfectly consistent, and are independent of the universe, then it seems proper to say that they reflect a transcendent, absolute, perfect, and independent mind."
This is a variant of the argument from design, which has many problems. For an apologist to say the laws of logic had a designer, they would need direct experience of how the laws of logic were actually formed by God and not simply what they are, to have any confidence in this argument.
- "[On "God is transcendent"] Yes, I admit this is more or less an assumption."
Logical absolutes are conceptual
- "The Laws of Logic are conceptual [i.e. they are of the mind] by nature. [because] Logic is a process of the mind. The Laws of Logic provide the framework for logical thought processes. "
This is an equivocation between the logic (the application of the absolutes) which is arguably conceptual, and logical absolutes which are not necessarily conceptual. Without demonstrating the absolutes being conceptual, the argument falls apart. 
So what? The point is argued at length in the CARM.org version of the argument but then not used in the later stages of the argument. The notion that concepts require a mind is not properly established, which is an explicit axiom in the conceptualist argument.
- "If the underpinning principles known as logical absolutes are not conceptual, then what are they? "
- "[One answer:] Neither conceptual or material."
This argument attempts to establish the logical absolutes as conceptual by set up a false dichotomy in which they are either material or conceptual. However, this is not a true dichotomy since there may be other possibilities and they are not even mutually exclusive. The dichotomy proposed by apologists does not even allow of the possibility of a spiritual basis for logic, which is somewhat ironic. Also, a skeptic does not need to know what something is (in other respects) to be able to know what it isn't in this respect.
- "I call this the Dillahunty Fallacy where you merely assert there is a 3rd option in order to falsify a dichotomy but aren't able to produce the 3rd option."
This is shifting the burden of proof on to the skeptic, which is itself a fallacy. It is up to the apologist to show the dichotomy is valid. Just saying "I can't think of an alternative, therefore the dichotomy is valid" is an argument from ignorance.
There are many counter arguments to TAG but they often only apply to a specific variant of the argument.
The premises of the argument are not accepted by its critics. For an argument to be persuasive, the axioms must start from mutually agreed statements. Both the "absolute knowledge/logic exists" premise and "God explains absolute knowledge/logic" premise are disputed. The apologist has asserted but done nothing to show that God is necessary for knowledge or logic to exist.
- "how can truths about the world which appear to say or imply nothing about human thought or experience be shown to be genuinely necessary conditions of such psychological facts as that we think and experience things in certain ways, from which the proofs begin? It would seem that we must find, and cross, a bridge of necessity from the one to the other. That would be truly remarkable feat, and some convincing explanation would surely be needed of how the whole thing is possible."
If the apologist offers to justify the premise that "God explains absolute knowledge/logic", they typically rely on circular argumentation.
Circular argumentation needed to support premise
TAG is not persuasive since it effectively assumes God as a premise. It is a case of "presupposing God in our epistemology and then using that epistemology" . The first premise is:
- "(1) If God did not exist, rational thought would not be possible."
The problem is how does an apologist know the first premise to be true? To defend it, the apologist would have to rely on scripture being true, which assumes God is true, which would be a circular argument or begging the question.
- "presuppositionalists can’t defend TAG’s first premise (while remaining “presuppositionalist”) without begging the question "
- "As is obvious, someone who does not already accept the conclusions of the argument is not likely to accept its premises. In this respect, the argument is fundamentally circular"
Many of the argument's proponents explicitly say the argument is circular:
"To admit one’s own presuppositions and to point out the presuppositions of others is therefore to maintain that all reasoning is, in the nature of the case, circular reasoning. The starting-point, the method, and the conclusion are always involved in one another"
"But are we not still forced to say, 'God exists (presupposition), therefore God exists (conclusion),' and isn't that argument clearly circular? Yes, in a way. [...] If Scripture is the ultimate justification for all human knowledge, how should we justify our belief in Scripture itself? By Scripture, of course!  [...] there is no alternative to circularity [...] no system can avoid circularity"
"[On the claim that "God has originated the laws of logic"] Again, I do admit slipping into a Biblical presupposition at this point."
Many critics also say it is circular:
- "First, it engages in question-begging—-assuming what one wants to prove. It begins with the assumption that God exists, and then concludes that God exists. Such reasoning would get you an “F” in any logic class worthy of the name!"
- "The transcendental argument for the existence of God is the argument which attempts to prove God’s existence by arguing that logic, morals, and science ultimately presuppose the Christian worldview and that God’s transcendent character is the source of logic and morals."
Apologists sometimes accept this accusation but then claim this specific premise is exempt by special pleading or the claim that all world views require presuppositions, so they are justified in this presupposition. To avoid the accusation, apologists would do well to label their premises, their reasoning and conclusions explicitly, and to define their terms.
Apologists sometimes respond by claiming their argument is circular but not "virtuously circular", which is a case of special pleading. It is ironic that apologists discard logic as soon as it is inconvenient, which shows logic is not absolute or fundamental.
Since the argument is circular, it is also redundant. TAG may be simply dismissed as unnecessary by both apologists and skeptics because God's existence is already implied by a premise of the argument.
Questionable premise: defining the "solution" to suit the problem
The argument seizes upon an epistemological problem and defines God in a way to be the solution. A reformulation of the argument would be:
- Premise: Epistemological problem X exists and has no non-theistic solution.
- Premise: If X exists and God has the attributes that solve X, God exists.
- Since "X exist" is a premise, the second premise is equivalent to: God has the attributes that solve X and God exists.
- Conclusion: God has the attributes that solve X and God exists.
So while the argument may be sound, it shows the premises are selected simply to define God into existence.
- "It's like if I said 'well there's presents under the tree, so Santa must ******* exist. Because if he didn't exist there couldn't be presents under the tree.' "
God is a poor explanation
- Main Article: Ultimate 747 gambit
Presuppositionalist apologetics tends to stay on the offensive and keep asking "why?" and "how do you account for?" questions until you hit bedrock at "how does logic exist" or "how does knowledge exist". The TAG proponent will declare victory if you don't have an answer, then baldly assert that they do ("God did it"). For this reason, Van Til considered TAG to be a reductio ad absurdum of non-theism, rather than a positive proof of God. 
It should always be remembered that theists are in the same position as non-theists once enough layers are peeled back. The question is how does knowledge or logic get established, not by who. When apologists refer to God as an explanation, they have not really explained anything since God is a bigger mystery than the one they are seeking to explain. They will also be unable to say exactly how God is able to establish logic and knowledge, except by vague statements about "God's nature". Well, that doesn't explain it either since that too is a big mystery. They've just pushed the question back a level; both the apologist and skeptic are faced with the Münchhausen trilemma which has no clear resolution. Perhaps the easiest way to move on from this conundrum is to point out TAG is a circular argument, which is arguably less attractive than a priori assumptions or psychologism.
- "they’ve simply replaced natural axioms with others that they prefer. There are still axioms at the bottom, so this is no improvement. [...] I’ll admit that “that’s just the way it is” isn’t completely satisfying, but “God did it” resolves nothing. The apologist won’t tell us why or how God exists; he just exists. This informs us as much as “fairies did it.” But if the Christian can have a fundamental assumption about reality (God), so can the naturalist (natural axioms) [...] But “God did it” is simply a repackaging of “I don’t know.” It tells us nothing new. I’m no smarter after hearing “God did it” than before. How did God do it? Why did God do it? Who is this guy and where did he come from? This is an answer that just brings forth yet more questions, and it never comes with any evidence to back it up."
- Main Article: Which God?
Even, for the sake of argument, accepting every point made, the only conclusion drawn is that there must be some intelligent origin of logic and knowledge. Unless God is arbitrarily assumed to be something capable of establishing the rules of logic, and this assumption has not been supported except by a priori assumptions, apologists have not shown God exists.
If anything, the argument implies deism in that God established logic and knowledge, then became passive.
Islam also uses presuppositional apologetics
- "For the Muslim, belief in Allah forms a foundational requirement of rationality and belief in Muhammad as the prophet of Allah follows from applying the rational mind to the evidence of his mission. "
Since both Christian and Muslim apologists use presuppositional apologetics, but arrive at mutually incompatible conclusions, the argument is a broken compass.
Because presuppositionalists believe acceptance of the Bible is primitive, there is some concern about whether or not they can have a non-Biblical justification for accepting the version of the Bible that they do.
The Biblical text has shifted over the years. It is debatable if current form of the Bible are an adequate representation of either the traditions of the early Church or a reasonable representation of the events that they purport to recount. One of the major issues in this case is the concern over the omission of additional sources from the Biblical Canon. Because presuppositionalists are, generally, protestants, there are some concerns about whether the authority of the early Church extended to the inclusion or exclusion of texts from the Bible. While this is generally an argument amongst Christians, who tend to have misgivings about papal authority, there can be a sharp point made by skeptics.
This argument is supposed to put the presuppositionalist in a dilemma: Any reference to the Bible in justifying the use of a particular version of the Bible is question begging and any admission that there is a non-Biblical reason for choosing a particular version of the Bible requires the presuppositionalist to give up the Bible as foundational, as such a justification constitutes an alternate foundation.
Logic and epistemology are human conventions
Logic and epistemology are human conventions that are adopted for the sake of utility. They do not require any "transcendent explanation". This position is known as "antirealism" and is well known in the philosophy of mathematics (logic being a branch of mathematics). The apologist cannot easily demonstrate mathematical realism rather than antirealism is actually true.
- "the sceptic can always very plausibly insist that it is enough to make language possible if we believe that S is true, or that it looks for all the world as if it is, but that S needn't actually be true "
Apologists sometimes respond by saying:
- "A convention--in this context--is an agreed upon principle. But since people differ on what is and is not true, then The Laws of Logic cannot be the product of human minds and, therefore, are not human conventions, that is, of human agreements.[...] This would mean that The Laws of Logic were invented as a result of an agreement by a sufficient number of people. But this would mean that The Laws of Logic are a product of human minds, which cannot be the case since human minds differ and are often contradictory.[...] They cannot be constructs of human minds because human minds contradict each other and themselves where The Laws of Logic do not."
Not everyone has to agree to establish a human convention. Based on existing philosophical ideas, a single person can formulate a system of logic and other people chose to adopt it or not. It so happens that classical logic is widely used in philosophy but it is not the only system of logic that is used. Ludwig Wittgenstein argued that conventions could be likened to "language games" in which a certain group of people adopted certain language usage conventions.
"'Reason' in language — oh, what an old deceptive female she is! I am afraid we are not rid of God because we still have faith in grammar."
Apologists argue that non-absolute languages cannot give rise to the absolute laws of logic:
- "To say the absolutes of logic are a result of the use of the subjective meanings of words is problematic. How do you derive The Laws of Logic from the non-absolute semantic structures of non-absolute languages? [...] If so, then the laws of logic are not laws."
The above problem is resolved by saying the Laws of Logic are not absolute or transcendent in the sense used by the apologist. They are as absolute as a definition (but definitions can change). Alternatively, this is resolvable by distinguishing between our (conceptual) formulation of logic and the (non-conceptual) absolute laws themselves.
- "If logic is the result of language, then logic came into existence with language."
That is correct, according to mathematical antirealism.
"I don't think it is a good argument because I agree with the Neutralist on this. I don't see any reason to think that the truth of 2+2=4 commits you to the reality of 2+2 or 4."
Alternative logical systems of axioms are used
There are many alternative logical systems that are used, apart from classical logic. These are referred to as non-classical logic. Which logical system to use in a particular circumstance is subjective.
- "In different systems of logic, there must be undergirding, foundational principles upon which those systems are based. How are those foundational principles accounted for? The same issue applies to them as it does to The Laws of Logic in classical logic."
Each logical system is a subjective convention, devised by humans to address a particular need. Usefulness is a subjective basis for selecting logical axioms. Apologists are absurdly claiming that any useful group of axioms is somehow proof of God! It seems as practically any phenomenon is claimed as evidence of God's existence.
Equivocation of "logic" with the "logical absolutes"
- "The Laws of Logic are conceptual [i.e. they are of the mind] by nature. [because] Logic is a process of the mind."
The statements of the laws of logic are a description of logic but not themselves the underlying necessary absolute logical truth.  Our concept of the laws of logic are contingent on our brains, while what they describe is (possibly) universal, non-contingent, essential and not conceptual ("of the mind"). The very fact they are expressed in language makes them contingent on language (or another human created system of symbols). The apologist equivocates between logic absolutes and our concept of the laws of logic.
- "You have built this on a logical fallacy. You have said that logic (our thought processes) is conceptual and therefore the absolutes upon which they are founded is also conceptual. And that is fundamentally the same as saying 'I have a concept of an apple, therefore the apple is also conceptual'. That is flawed. "
In other words, this is the fallacy of division.
The question is meaningless because any answer must assume logic is true and therefore is necessarily circular.
- "The demand to explain the laws of reality is malformed—explain in terms of what? There’s no larger context in which to explain them. The buck stops with these fundamental properties. "
- "you are asking us to provide a reason based on logic, so you are asking us to beg the question that logical absolutes exist. "
The question also may depend on causality or time, which is meaningless with respect to transcendent absolutes.
- "You are asking 'why are the laws of absolute what they are?' and 'why' is a question regarding causality. And causality is necessarily temporal. And we have already excluded [that] because we are talking about something that transcends time. You are asking something that is essentially nonsense. "
Knowledge does not need a formal basis
Some philosophers argue that knowledge and logic do not need to be formally justified at all. Transcendental argument simply addresses a non-problem.
"I mistrust all systemizers and avoid them. The will to a system is a lack of integrity."
Argument implies God exists outside of logic
The version of the transcendental argument for the existence of God which claims that the classical laws of logic depend upon God may be refuted simply by pointing out that its conclusion, if taken seriously, is absurd. If the classical laws of logic depend upon God for their existence, then the classical laws of logic must not apply to God. For instance:
- Since the law of the excluded middle would not apply to God: any statement about God, as well as its negation, may both be true. So, “God exists,” and “God does not exist,” may both be true. Demonstrating “God exists,” would fail to imply that “God does not exist,” is false.
- Since the law of non-contradiction would not apply to God: contradictory statements about God may be true. Therefore, “God exists and does not exist,” may be true.
- Since the law of identity would not apply to God: God may be other than, or not, God.
Apologists address omnipotence paradoxes such as "can God create a rock so heavy that he can't lift it?" but saying God cannot do anything except that which is logically impossible. This claim is based on God being bound by logic and therefore exists separately and independently of God. God cannot both be and not be the basis of logic and the apologetic arguments are mutually incompatible. While this objection addresses TAG involving the question "what is the basis of logic?" it does not answer "how do humans know of the objective laws of logic?" TAG is arguably based on addressing epistemological questions from the point of view of humans.
- "Is something reasonable merely because God proclaims it so, or does God proclaim something reasonable because it is? "
This problem is similar to the Euthyphro dilemma which concerns morality rather than logic.
- "Show me that the laws of logic are optional or different in an alternate universe. Otherwise, we can presume that the logic that we have is universal. Let’s say instead that reality just has properties. Or: properties are a consequence of reality."
Apologists object by saying:
- "This is begging the question by saying that they exist because they exist and does not provide an explanation for their existence."
Apart from being no worse than the arbitrary a priori assumptions and circular reasoning used by TAG, it is up the the apologist to prove they don't exist. Otherwise, this is shifting the burden of proof on to the skeptic.
Apologists don't seem interested in proving a God who is not involved in being the basis of logic and knowledge.
- "Atheism cannot account for the necessary preconditions for intelligibility, namely, the existence of The Laws of Logic. "
Even if we assume that atheists today cannot account for the laws of logic, this does not mean it might not occur in the future. The argument is a typical god of the gaps claim. The apologist also needs to prove that without theism, the laws of logic can never be accounted for. Naturally, the burden of proof is on the person making the claim: in this case the apologist.
Mathematics and logical absolutes can exist independently of a mind
Similar to logic, the number 4 is “transcendent” by the TAG definition. It isn't a 'thing' that 'exists'. It cannot be photographed, frozen, weighed, or measured. It is always the number 4. It always remains the same. It always remains true.
However, if there were no minds in existence to conceive of the number 4, the shape we currently call a square would still have the same number of sides it has now. It would not physically gain or lose any sides. The abstraction of the number 4 is conceptual, but the concept isn't dependent on a transcendent mind for the real world underpinning of the concept to remain true.
Logic and existence of knowledge may be non-contingent
The logical absolutes may be non-contingent on thought. This would make it impossible for them to be established by the mind of God. Apologists respond by saying they are part of God essence or nature, in which case the conceptual nature of the logical absolutes is irrelevant.
If logic and knowledge are established by God, he might not have had any choice in the matter. Of course, it may be that some other universe exists where things have contradictory attributes like being a rock and not a rock at the same time.  However, it seems reasonable to assume that non-contradictory existence is the norm. The burden of proof is on the apologist to show that what God did was contingent on his choice for TAG to demonstrate anything of significance.
TANG or the "Transcendental argument for the non-existence of God" attempts to show that such logical absolutes cannot be absolutes if they are subjective and contingent on God.  God could simply ignore the number 7 or believe that killing children is good and the logical absolutes would change. Therefore, logic would not be absolute or objectively true, but rather subject to the whims of God. Since this property of logic is not observed, God does not exist.
Since the transcendental argument can be used to conclude that god both exists and doesn't exist, it is a broken compass argument.
Secular foundations for logic and knowledge
- "Furthermore, the argument fails to propose how the atheistic perspective can account for the Logical Absolutes. "
There are actually many theories of epistemology and reality that do not rely on God. Ultimately most of them eventually come down to the Münchhausen trilemma i.e. eventual a priori assumptions, infinite regress or psychologism. TAG provides no particular advantage over these theories (apart from agreeing with a theist's preconceptions). These views include:
- Secular idealism, (Phenomenalism?)
- Empiricism and materialism
TAG may be considered inferior because it introduces entities without any advantage. We might as well just accept logic and knowledge a priori. TAG is therefore subject to Occam's razor.
Failure to show non-theism is unsatisfactory
"Is it possible for an apologist to refute all the alternatives to Christian theism? Van Til thought that it is possible, for in the final analysis there is only one alternative."
Since the apologist has not shown that all possible non-theistic views are unsatisfactory (since this is impossible to achieve in practice), this is an argument from ignorance. Simply asserting it to be unsatisfactory is not a reasonable or persuasive argument.
Self refuting argument
Presuppositions have a place in communication where a sentence's meaning makes implicit references to shared concepts that are often based on experience. In contrast, presuppositional apologetics claim that views that are based on reliance of sensory experience is potentially flawed and only religious scripture/God is sufficient. This negates the apologist's argument since their claim relies on human sensory experience, language, human cognition and further presuppositions to be meaningful and be understood:
- "When language comes into existence, it is a mix of hard wired biology, structures in the brain, observation of the world around us, our ability to reflect on concepts we form. By dismissing naturalistic [communicative] presupposition, in his attempt to give faith based presupposition precedence, Sye cuts away the foundation of Christian suppositionalist superiority and his argument crumbles to dust. "
In other words, assuming a single holy book or God is the sole foundation is not enough to bootstrap or justify knowledge, logic, communication and reason. We require further presuppositions which the apologist has already rejected. As a specific example, even if the Bible is foundationally true, you still need to read it to understand it. Therefore, apologists are also required to assume there is no Descartes' evil demon that confuses our senses and makes us misinterpret the Bible. This is just one of many unstated presuppositions required if the Bible is to be used in the foundation of knowledge. Once all the hidden presuppositions of the presuppositionalist are uncovered, the presuppositionalist is in the same situation as an atheist philosopher; the Bible is then redundant via Occam's razor.
Basic structure of the argument
- ""If we have only two possible options by which we can explain something and one of those options is removed, by default the other option is verified since it is impossible to negate both of the only two exist options." This is not addressed, and it needs to be in a proper criticism of the argument. "
While the basic logical structure of the argument, as quoted here, is valid, the problem with TAG lies with the issue it attempts to address, its definitions, concepts, application of logic and axioms. The above statement can be easily misapplied and can be a false dichotomy. Some variants of TAG are valid arguments but no version is sound, or the soundness is indeterminable in practice. This is often the case with circular arguments such as TAG.
Shifting the burden of proof
- "In what sense are they the result of natural existence? How do conceptual absolutes form as a result of the existence of matter?  Furthermore, if it is not necessarily so that the underpinnings of formal logic are conceptual, then falsify the assertion by demonstrating how these underpinnings are something other than conceptual."
An argument can be refuted by many different means, not just by counter-example. Also this attempts to shift the burden of proof onto the skeptic. It is up to the apologist to show that logic is not a result of natural existence rather than to assume it is conceptual without evidence.
- "You are essentially asking me to prove that God doesn't exist and claiming that God does exist in your mind until I actually demonstrate that he doesn't. You are doing the same thing with these logical absolutes because you are saying I can't tell you what they aren't until I tell you what they are. "
Acceptance of "logic is transcendent"
- "[Critics] accepts the idea that logical absolutes are not dependent on the universe (remember it said the first problem was after the TAG argument stated that LA's are not dependent on the universe)."
An earlier version of this article stated "first major problem with the argument occurs in 5.1-4" (emphasis added). That does not preclude problems earlier in the argument. The assumption that the logical absolutes are independent of the universe is obviously not accepted by many of TAG's critics. This wiki is more a catalogue of arguments and counter arguments; it does not attempt to present a single unified world view.
Accounting for the existence of logic
- "This still does not account for the existence of The Laws of Logic."
Additional concerns about Platonic epistemology
Van Tillian apologetics generally relies on Platonic epistemology.
Criticism from Reformed epistemology
Proponents of reformed epistemology point out that Platonic theory seems to be treating the existence of God as the existence of a category, rather than as the existence of an object (or fact). If we accept that God is a particular "form" in the sense of Platonic epistemology, then there is some concern about whether or not God is actually an instantiation.
For the reformed epistemologists, God must be actual, and it will not do for God to be a general claim which has a number of instantiations. The reformed epistemologists have a concern with the Platonic epistemology that it requires them to create a singular category for God, of which God would be the only member. The concern, here, is that many of the presuppositionalists want God to be, or be indistinguishable from, that category.
The major issue is that Platonic epistemology maintains that categories are objective. This is not something that most epistemologists are willing to commit themselves too, as it makes some serious presuppositions about philosophy of mind which are not accepted in the field. Most epistemologists maintain that, to some degree or another, the categories that exist in logical systems are a cognitive necessity, but not objective. Whether there are any objective category is an open question among philosophers, but most reject the idea that all epistemological categories are objective.
Perceptual categories, like color, are now understood to be incredibly fluid across cultures. This presents a problem, as the property of red-ness is not an objective property of the objective, but a property of the object as it is represented in the brain/mind. The property of the object has to be described differently, because color is too fluid to be used as an objective descriptor.
Most secular epistemologists now reject Platonic epistemology in favor of Kantian or Quine-ian epistemology. Even Cartesian epistemology (despite some of the concerns in cognitive science and some of the infinite regression concerns) is often considered more sound than Platonic epistemology.
- ↑ 
- ↑ The Great Debate: Does God Exist? Dr. Greg Bahnsen versus Dr. Gordon Stein, At the University of California, Irvine, 1985
- ↑ 3.0 3.1 3.2 3.3 3.4 
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 
- ↑ -Sigh- Oh Sye - Can you be Wrong About Everything you Claim to Know?
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 [
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 
- ↑ 
- ↑ 
- ↑ 
- ↑ The Refining Reason Debate, May 31st
- ↑ 
- ↑ 
- ↑ Richard Ashcraft, Faith and knowledge in Locke's philosophy, in John Locke: Problems and Perspectives: A Collection of New Essays, ed. John W. Yolton, 1969
- ↑ 15.0 15.1 
- ↑ 16.0 16.1 16.2 James Anderson, If Knowledge Then God: The Epistemological Theistic Arguments of Plantinha and Van Til
- ↑ 
- ↑ 18.0 18.1 18.2 18.3 
- ↑ 
- ↑ 
- ↑ Barry Stroud, Kantian Argument, Conceptual Capacities, and Invulnerability in Understanding Human Knowledge, 2002, p158-159
- ↑ 
- ↑ Comment by Dan, 14 March 2012 at 08:56
- ↑ Understanding Torture By J. Jeremy Wisnewski
- ↑ 25.0 25.1 25.2 John Frame, Five Views on Apologetics, 2010
- ↑ John M. Frame, The Doctrine of the Knowledge of God (Phillipsburg, NJ: P & R Publishing, 1987), 130.
- ↑ 
- ↑ 
- ↑ 
- ↑ Stroud 1968 [2000b: 24]
- ↑ 
- ↑ Why the Transcendental Argument is Fallacious
- ↑ 
- ↑ 
- ↑ 
- ↑ 
- ↑ 
- ↑ Philip Rose, How 2 Debate Theist GOTCHA Arguments 4, 2 Jun 2012
- ↑ 
- Fallacy of division
- Fallacy of reification
- False dichotomy
- Special pleading
- Ontological argument
- Argument from the meaning of life
- Stolen concept
- Sorry, Denise but God didn't make numbers – Article by Mark Chu-Carroll PhD on Good math, Bad math.
- Slick Logic – Youtube Theoretical BS run down on the TAG argument.
- Apologist Caller: Matt Slick & Transcendental Argument PART 2/2 - A.E. #592
- Atheist experience #593 – Youtube AE television debate between Matt D and Matt Slick.
- Matt/Matt Debate – Youtube Theoretical BS commentary of the atheist experience debate.