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Welcome! This is the place to ask the community of experts and other fallacyophites (I made up that word) if someone has a committed a fallacy or not. This is a great way to settle a dispute! This is also the home of the "Mastering Logical Fallacies" student support.

Dr. Bo's Criteria for Logical Fallacies:

  1. It must be an error in reasoning not a factual error.
  2. It must be commonly applied to an argument either in the form of the argument or in the interpretation of the argument.
  3. It must be deceptive in that it often fools the average adult.

Therefore, we will define a logical fallacy as a concept within argumentation that commonly leads to an error in reasoning due to the deceptive nature of its presentation. Logical fallacies can comprise fallacious arguments that contain one or more non-factual errors in their form or deceptive arguments that often lead to fallacious reasoning in their evaluation.

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Scott Paech

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Scott Paech

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circular reasoning
Thu, Apr 30, 2015 - 06:02 AM

How do I respond to presuppositionalist's claim that circular logic is not fallacious?

Because presuppositionalists say that since every worldview commits this fallacy. it leads to the absurd conclusion that every worldview is invalid.(I am applying the principle of charity here, which means that the argument they present is actually weaker)

presuppositionalism is a school of Christian apologetic who think that the Christian god is the only thing that can account for the "existence" of logic, truth, science, morality.(I could keep on going forever)

To be fair, they only do this to respond the fact that someone pointed out that presuppositionalism commits the circular logic fallacy.

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Bo Bennett, PhD
Author of Logically Fallacious


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Bo Bennett, PhD

Author of Logically Fallacious


About Bo Bennett, PhD

Bo's personal motto is "Expose an irrational belief, keep a person rational for a day. Expose irrational thinking, keep a person rational for a lifetime."  Much of his charitable work is in the area of education—not teaching people what to think, but how to think.  His projects include his book, The Concept: A Critical and Honest Look at God and Religion, and Logically Fallacious, the most comprehensive collection of logical fallacies.  Bo's personal blog is called Relationship With Reason, where he writes about several topics related to critical thinking.  His secular (humanistic) philosophy is detailed at
Bo is currently the producer and host of The Humanist Hour, the official broadcast of the American Humanist Association, where he can be heard weekly discussing a variety of humanistic issued, mostly related to science, psychology, philosophy, and critical thinking.

Full bio can be found at
Print Thu, Apr 30, 2015 - 07:51 AM
Hi Scott,

As much as it pains me to say this, presuppositionalists do have a point here—kind of.

First your point about absurdity. This is based on the assumption that worldviews containing fallacies must be invalid. In argumentation terms, "invalid" does not mean "not true." Remember that just because something is fallacious, does not mean it is not true. For example, "Apples are good for us because they are all natural." The premise that "apples are good for us" is true, although the fallacious reasoning that follows does not make it true. Likewise, the fact that one might justify their worldview with circularity does not require the worldview to be false—just their justification of it.

A trick of the presuppositionalists is to hold others to impossible standards while using special pleading to excuse themselves from such justification. One cannot use reason to justify reason (that would be a form of circularity), but that is what the presuppositionalists demands. Words such as "justification," "account for," and "explain" all are part of the reasoning process. So when the presuppositionalist asserts that "God" is foundation for everything (including reason), they are using "reason" to make this assertion, thus circular.

To escape this circularity, we don't justify—we accept. We accept certain self-evident truths provisionally until we have good reasons not to. We accept the fact that we exist, yet by playing word games we can make it impossible for someone to prove their own existence by using impossible standards. These word games cause people to cast doubt on what we rationally accept as self-evident. In a way, we "presuppose" reason, and the presuppositionalist presupposes "God." The difference is, the concept of "God" contains dozens, hundreds, or even thousands of presuppositions such as: God is a being, God is intelligent, God is good, God is eternal, God exists outside of space and time, God has a son name Jesus who died for our sins, God does not want us to eat shellfish, etc. Some even "presuppose" that God wrote/inspired every word in the Bible so that everything in the Bible is "presupposed" to be true, as well. This is sort of like presupposing that "everything is true." This one presupposition contains every presupposition (including "everything is false"), and this leads to absurdity.

The critical thinker accepts as little as possible as "self-evident." The presuppositionalist fails to delineate between that which he must accept, and that which he wants to believe. My advice, don't bother arguing circularity with the presuppositionalist. In fact, don't bother arguing with the presuppositionalist at all, since they already presuppose that they are right, and they can't possibly be wrong.

Update: Monday, Mar 18, 2019 08:17 AM

Anonymous comment:

I think you've presented a hasty generalization yourself. Your premise supposes that all presuppositionalists presuppose all of those. Rather, if we presuppose an intelligent designer, many find the most consistency in some of the topics you label as presuppositions.

My premise is that presuppositionalists who presuppose a god include many (dozens to thousands depending on belief) of attributes. Again, the critical thinker accepts as little as possible as "self-evident." Presupposing "an intelligent designer" is presupposing a host of attributes that are unnecessary and completely unwarranted. We don't presuppose it because it fills the gaps where we have tough questions (see God of the Gaps fallacy). If that were the case, we can all just presuppose "magic" and every question can be answered by inserting "magic" (i.e. apparent consistency). Further, as atheists have demonstrated for millennia, for every question a god "answers," it results in several more that the theist often address by "you just need to have faith," "God's ways are not our ways," "God is a mystery," "Our minds can not possibly understand the greatness of God," "All of our questions will be answered when we meet God." No, one cannot reasonably presuppose an intelligent designer any more than one can simply presuppose magic. If one does, they are not practicing critical thinking.
Bo Bennett, PhD
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