What's a Presupposition?
noun: presupposition; plural noun: presuppositions
a thing tacitly assumed beforehand, or taken for granted, at the beginning of a line of argument.
synonyms: presumption, assumption, preconception, supposition, first-principle, premise, postulation
Why Should I Care?
Everyone has presuppositions -- ideas or assumptions they take for granted. They may be true or they may be false, but everyone has them. Often we assume that others share our presuppositions, but frequently they don't. Being able to recognize one's own hidden assumptions and those of other people can be very helpful in understanding why people come to differing conclusions and can help prevent us from committing logical fallacies or errors in our thinking.
Analysing the most basic first-principles of any worldview, faith, or religion is one of the fastest ways to discern if that worldview is true or false. Sometimes, when the presuppositions are actually considered, the errors in the view are blatant and undeniable.
How Does This Work?
Presuppositional apologetics involves a very simple procedure or method. Any specific application of the method may be difficult or get complicated, but the method itself is very simple. It involves two steps, one offensive and the other defensive.
- Offense: Internally analyse the non-Christian's worldview and show how it is contradictory.
- Defense: Internally analyse the Christian worldview and show how it is consistent.
Notice that each worldview must be internally analysed. A worldview can't be analysed from the outside. To analyse it from the outside is to assume things that it doesn't assume. This leads to what is known as "straw-men fallacies", where the worldview is mischaracterized while it is being investigated.
Nobody wants that.
Many people want to look at evidence before accepting a worldview. But evidence is always understood based upon one's worldview, not the other way around. If we interpret evidence according to our own view in order to investigate someone else's view, we'll never actually see their view for what it is.
A full presuppositional apologetic involves both offensive and defensive steps, but sometimes only one or the other step is needed. Generally, in a one-on-one conversation with a non-Christian, employing both steps is very important. But good offensive and defensive arguments can also stand alone.
Examples: On the Offense
Each of these examples are just intended to be one piece of a conversation with a non-Christian, to assist the Christian in pointing out problems with the non-Christian's perspective. None of these particular examples are proofs of Christianity -- they just argue against forms of non-Christianity.
Deductive Argument that Atheism is False
Atheists presuppose two things that are in fact mutually exclusive: they cannot both
be true. The first is that their own conclusions are rationally justified, and the
second is that there is no sovereign rational creator. The combination of these two
presuppositions makes the worldview of the atheist inherently contradictory.
Deductive Argument that Polytheism is False
Polytheists also presuppose two things that are mutually exclusive. The first is
that non-contradiction is both universal and invariant, and the second is that there
are multiple sovereign creators. But as Socrates pointed out in Plato's Euthyphro,
the combination of these two presuppositions makes the worldview of the polytheist
Deductive Argument that Pantheism is False
Pantheists likewise presuppose two things that are mutually exclusive. The first is that
their own conclusions about the present are rationally justified, and the second is
that multiple entities share absolute ultimacy, much like polytheists. These two views,
however, cannot both be true.
Deductive Argument that Unitarianism is False
Unitarians, too, presuppose two things that are mutually exclusive. The first is that
their version of god is rational. The second is that his ultimate reason for his actions
is not himself. As the proof demonstrates, this makes unitarianism incoherent.
In Printed Form
Along with numerous other authors including Don Landis, Bodie Hodge and Roger Patterson, Timothy McCabe contributes analyses of various world religions and cults in this volume from Master Books.
Who is Timothy McCabe?
Born in Virginia in 1974, Timothy McCabe grew up overseas, the son of a diplomat. Influenced by the cultural diversity he experienced in the Philippines, England, India, Japan, and a variety of other nations, much in life seemed very culturally subjective to him. After high school, McCabe began to slowly walk away from the values he had been raised with. Eventually, this led to emotional distress, broken relationships, failed dreams, and public humiliation.
Then Jesus saved him.
From that time on, amid a world laden with cultural subjectivity, Tim has trusted that Jesus Christ will provide for him; that God's revelation in the Bible, while often apparently open to interpretation, cannot possibly be false; and that some truths are not based on human opinions. The facts of God's existence, man's sin, the problem this creates, the solution through the sacrifice of Jesus Christ... these objective truths transcend every culture.
Tim now resides in Indiana with his wife and daughter. In his spare time, he writes novels that have never been published and contributes to the God Contention website, which he also designed and developed.
Virginia Polytechnic Institute and State University
American School in Japan
"Why does the creator of the entire universe get the value of pi wrong (2 Chron 4: 2)?"
God didn't get Pi wrong. Rather, He rounded to the nearest cubit. "Also he made the cast metal sea, ten cubits from brim to brim, circular in form, and its height was five cubits and its circumference thirty cubits." -2 Chronicles 4:2 If we were to write down the whole value of Pi, or in this case, Pi times 10, we would never finish writing. Therefore, whenever anyone, Creator of the universe or not, writes down the value of Pi for us to read, it is always rounded.
"Are all presuppositions equally valid? If not, how does one determine which are more valid than others?"
Internal consistency is the most common method I know of for determining the truth value of presuppositions. The test of internal consistency is what presuppositional reasoning is all about. If, for example, a view presupposes "A" and "not-A" at the same time and in the same way, then, in that worldview, reasoning, knowledge, learning, meaning, morality, science, mathematics -- everything -- becomes utterly incoherent.