Philosophy Friday: Let’s Talk About Logic

February 21, 2014 — Leave a comment

I’ve been going back and reading through my long abandoned philosophy series. Some of it aged well. Some did not. I was definitely doing a lot of thinking at loud, as opposed now, when I mostly think to myself.

In thinking about thinking, I thought it might a good time to think out loud about logic. It’s kind of a prelude to philosophy (see my review Tuesday of a book by that title), and is important to have understand as we do some philosophical investigations.

Logic is the principles governing correct and reliable arguments. 1 An argument consists of presenting evidence with an inference (conclusion) drawn. Typically, arguments are divided into two categories:

  • Inductive (yields probable conclusions)
  • Deductive (yields certain conclusions)

Within these forms, three laws govern the actual arguing:

  • Law of identity (T is T and F is F)
  • Law of non-contradiction (No T and F)
  • Law of excluded middle (T or F)

Very few will deny these principles are true. This is because it would be making a claim about what is false, but destroying the ability to differentiate between truth and falsehood. These laws of logic are propositions that specify what truth-values other propositions can and cannot have.

Propositions themselves are language-independent, which means they can be expressed in language but are not reducible to language. This means the same true proposition can be effectively expressed in multiple languages. This also means that the laws of logic exist beyond specific language based expressions of them.

The word for this “existence beyond” is transcendence. Because the laws of logic are transcendent, they are said to apply to all possible statements in all possible languages. Laws of logic are truths, about truths, that exist independent of specific truth statements.

Because the laws of logic are also necessary for thinking, it is hard, if not practically impossible to deny their existence and still formulate a coherent worldview. Something necessary for for thinking itself is a preconditions for intelligibility (P. I.) P. I.’s are just what they sound like, the conditions necessary to make human experience intelligible. I would say by definition, any worldview that cannot account for P. I.’s is unlikely to be true.

In a discussion/argument, if a person appeals to something being “illogical” they are invoking the laws of logic . To credibly do so, they must be working from within a worldview that accounts for those laws. Otherwise, they are working off of “borrowed capital” and something critical to the expression of their worldview comes from another view they may even be trying to deny. This is illogical.

Now, because of all this, many people consider the laws of logic to necessarily exist. Everything that exists either exists contingently or necessarily. Something exists contingently if it is possible that it does not exist. Something necessarily exists if there is no possible world or scenario in which it could not exist. If the laws of logic exist necessarily, they must exist in all possible worlds in order for anybody to both know anything and to also be able explain what they know to anyone else. This makes the laws of logic a precondition for the intelligibility of knowledge, as well as the precondition for all arguments.

If laws of logic are truths that necessarily exist and transcend particular expressions of them, then the laws of logic must be non-physical, or immaterial. Things that exist necessarily, are by nature, non-physical since any physical or material object we could consider might not, or will not always exist. If something is not physical or material, it is mental, and this makes sense for classifying the laws of logic. In short, they are mental entities that exist as thoughts.

Thoughts are intentional, both in terms of what they are directed toward, and the specific content they have. As an example, I think Chipotle is delicious. My thought “Chipotle is delicious” is directed toward a the Chipotle restaurant in general, and my perception of their burritoes. While Chipotle physically exists, as does its delicious food, the thought where I draw them together intentionally does not have physical existence. You could measure the activity in my brain while I think the thought, but you cannot measure my brain activity and reconstruct the content of my thought (or the taste of the burrito). To think that is possible is not much different than thinking if you give a technological explanation of the pixels of the screen on which you are reading this post, and go into enough detail, you will be able to explain the content of my blog post. This is because information is non-physical in nature, and thoughts are about information. Information can be inscribed physically, but if the physical thing that contains the information is destroyed, the information still exists in mental form.

Earlier we noted every human is a contingent being, and therefore every human mind is contingent. If that’s the case, then the laws of logic must be thought by a necessarily existent mind. In other words, if we are all contingent and non-transcendent beings, we cannot, even collectively be the basis for something like the laws of logic. They must be thought first by a necessary and transcendent mind possessed by a necessary and transcendent being. To be necessary, this being must be non-physical. Additionally, this being must also be personal, and the only entity that fits all these criteria is the Truine God of the Bible.

Logic is therefore dependent on the existence of God. If this is true, then every logical argument presupposes the existence of God. Interestingly, this would apply to any argument constructed to disprove God’s existence. Atheism is therefore highly ironic for it must formulate its position by assuming the mind of God in order to then disprove God’s existence. This type of argument against atheism is called a reductio ad absurdum (a Harry Potter spell meaning “reduce to the absurd”) Remember earlier we talked about preconditions of intelligibility and how sometimes one worldview will smuggle in borrowed capital to bolster its claims. This is what atheism necessarily has to do.

That is rather illogical, though I haven’t found any atheists that agree with this conclusion. However, it is a deductive argument, so in order for the conclusion to not be certain, one or more of the premises must be proven false. But, in order to prove it false, an argument would need to be constructed that implicitly assumes the existence of God, and that is the horns of the dilemma so to speak. This argument could be expanded further (and it is in the article I mention in the notes), but I tried to put it as compactly as possible without listing it in bullet points. If I did though, here’s what it would look like:

  1. In order to prove anything, you must use the laws of logic
  2. The laws of logic therefore exist necessarily
  3. Necessary things exist non-physically
  4. The laws of logic are therefore non-physical (2 + 3)
  5. Non-physical things are mental things
  6. Mental things exist as thoughts
  7. Necessary thoughts must be thought by a necessary mind (2 + 4 + 6)
  8. The Triune God of the Bible possess a necessary mind
  9. Therefore the laws of logic are grounded in the mind of God (7 + 8)
  10. All arguments presuppose the existence of God


  1. Much of what I say here is heavily indebted to a Philosophia Christi article, “The Lord of Non-Contradiction: An Argument for God from Logic” James N. Anderson and Greg Welty (13:2, 2011). I distilled the main argument from this article into a PowerPoint presentation, and now I am reforming it into a blog post. I came up with a similar, but less developed argument on my own prior to reading this article.


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I'm an avid reader, musician, and high school Bible teacher living in central Florida. I have many paperback books and our house smells of rich glade air freshners. If you want to know more, then let's connect!

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