. Understand the Building Blocks of Logic

Understand the Building Blocks of Logic


Sometimes it seems like philosophy has given up on the concept. Postmodernism tends to treat it as relative; poststructuralism tends to treat it as an attribute of language, not reality.

That’s why it’s so refreshing to read a philosopher who sets out to build a framework for proving what’s true: Aristotle.

3 Rules of Thought

Aristotle wrote on everything from biology to poetry to rhetoric, but he’s best known for his meticulous work on logic. In the Organon (six of Aristotle’s core texts—Categories, On Interpretation, Prior Analytics, Posterior Analytics, Topics, and Sophistical Refutations) and the Metaphysics, Aristotle developed the classical Three Rules of Thought, without which even basic communication would be nearly impossible:

  1. The law of identity: every thing is the same as itself and different from other things. A is the same as A; A is distinct from B.
  2. The law of noncontradiction: two or more contradictory statements cannot both be true in the same sense at the same time. If we claim that x equals 1 and that x also equals 2, something has gone wrong.
  3. The law of the excluded middle: either a statement is true or it’s false.

If these laws seem totally self-evident, that’s part of their force. From Euclid and Pythagoras on, most technical proofs have started with universally accepted premises (axioms) and moved through valid steps (premises) to reach nonobvious conclusions. The Rules of Thought sound fundamental enough to be axioms, but they’re really rules of inference: principles that govern whether a move from one premise to another is valid. That means that, in the Aristotelian framework, they’re raw tools we can use to determine what’s true.

(By now it’s becoming clear why, agree or disagree, Aristotle can’t be avoided: if you try to demonstrate that something’s true, you’re almost certainly taking part in Aristotelian logic.)

What does this mean for theology?

Christianity is concerned with truth; it’s little wonder that Aristotle’s framework has proved influential.

Aristotle was also the one behind the deduction and induction you kind of remember from high school. A refresher: deduction moves from the general to the specific; induction moves from the specific to the general. So if Aristotelian induction lets you work from an specific observed aspect of the world to a general claim about science, it also lets you work from a specific observed aspect of the world to a general claim about God. (In that sense, the watchmaker argument—that the universe, like an intricate watch, testifies to the hand of a creator—is inductive.) If Aristotelian deduction lets you work from an axiom to a specific claim, it lets you work from the Bible to the particulars of theology.

Aristotle’s main influence on Christianity has been through Thomas Aquinas, who convinced the church that Aristotle’s methods were preferable to those of Plato. Aquinas established five famous proofs of God’s existence, and three in particular build on Aristotle’s logic:

  1. First Mover, which comes directly from Aristotle’s Physics: If all motion is caused by some prior force, and if the world is filled with motion, where did the first motion come from? (From God.)
  2. First Efficient Cause: If all situations have a cause, what do we make of the cause at the start of it all? (It is God.)
  3. Necessary Being: Not all things in the world are merely possible; some are necessary. A necessary thing can be caused by another necessary thing, but that introduces the infinite regress invoked by the previous two proofs; there must be something that is necessary in itself. (That thing is God.)

These ancient arguments remain influential and popular with apologists like William Lane Craig. Of course, apologetics is more than just logic. It’s also rhetoric—argument—and Aristotle has much to teach on that as well . . . but we’ll leave that for another post.

Learn from the father of logic

Aristotle wasn’t a Christian thinker, but his works are tremendously important. Noet offers Aristotle’s core arguments in the 12-volume Works of Aristotle Collection—the Organon, the Metaphysics, and more. What’s more, the Noet editions let you study in ways that the ancient Greeks could only dream of: when Aristotle argues against Plato, you can jump directly to Plato’s arguments; when modern apologists cite Aristotle or the Three Rules of Thought, you can see the evidence for yourself.

If you’re interested in truth and logic, this collection is a gem.

Understand the building blocks of logic: pick up the Works of Aristotle Collection today.

Or get an even better deal: go with Noet’s Ancient Philosophy Bundle, which also gives you the dialogues of Plato.

Written by
David Davidson
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  • Prospective buyers need to be aware that, unlike Plato, Aristotle is not a popular classic. Plato wrote in dialogue form and has vivid characters. So did Aristotle according to the ancients. None of his dialogues ate known to have survived, thus far. What we have of his work are not his works but something more like lecture notes compiled by his students and probably students of his students. Consequently even in translation to English they remain dry and difficult and some stuff necessary for our comprehension gets left out. Such being the nature of lecture notes. Well worth it for anyone who has taken an introductory course in logic. Otherwise Plato is great and will probably get you to a point where reading Aristotle makes sense

  • Logos needs to supplement Aristotle to reflect the actual logic of theology. For example, Aristotle did not fully accept the principle of the excluded middle – his classic example is tomorrow's sea battle. [Read Aristotle to fill in the details]. Boethius, Peter Abelard, Richard of Campsall, William of Ockham and John Buridan are all major Christian figures building on Aristotle's syllogistic logic. And, of course, Peter Kreeft is the obvious person to read before Aristotle – his Socratic Logic, that is.

  • Good point, Martha. I would suggest Van Til or Brahnsen (sp?) for "theology logic." Both are excellent authors and the presupposition for presuppositional apologetics :)

  • Thank you Martha Smith and Steven Long for filling out what needs filling. My background is Classics — not philosophy, not theology. Plato first has always been my advice to interested people. It still holds well for Aristotle's books on topics no longer considered hard-core philosophy. Say , Poetics, or the Nicomachean Ethics as an introduction. Certainly no one should seek to read the Organon without some preparation. Even with it there will be tough patches. BTW scholarly miracles are happening in the vicinity of Vesuvius. The large charred library found in the Pompeii – Herculaneum area is becoming readable due to advances in electron microscopy. They make it possible to get page by page "photographs" without unrolling the scrolls, which would destroy them. Archaeologists think it may have been a primarily philosophical library. A few early translations are being prepared in Naples, or were a few years ago when I talked to a graduate student there who was working on one of the teams. The big problem, she said , is funding. But for future generations, who knows? Maybe a few of Aristotle's dialogues will be well translated and available and he will become popular.

Written by David Davidson