# What is the difference between dogma and an axiom?

My understanding of axioms is that they are self evident truths that require no proof, which in my mind is similar to a dogmatic belief in the sense that dogma is a set of beliefs or doctrines that are established as undoubtedly in truth.

• Taking words from your own question, what is the difference betweeen "truth" and "belief"? That should give you an answer to your question. Commented Jan 31, 2013 at 13:39

Axiom is a statement taken to hold within a particular theory. One can combine the axioms to prove things within that theory. One may add or remove axioms to the theory to get another theory:

Euclid: ... 5. If a line segment intersects two straight lines forming two interior angles on the same side that sum to less than two right angles, then the two lines, if extended indefinitely, meet on that side on which the angles sum to less than two right angles.

Lobachevsky: ... what Euclid says except (5)

Dogmas are axioms of cultural, religious, political theories. Again, one may add or remove dogmas to get a new theory, e.g.:

Arius: ...the Son is not unbegotten ... before he was begotten, or created, or purposed, or established, he was not.

Nicean Council: ... those who say: 'There was a time when he was not;' ... are condemned by the holy catholic and apostolic Church.

The difference is that it is perfectly ok to handle different sets of axioms in, say, mathematics and prove a theorem in Euclidean geometry one day and a theorem in Lobachevskian the next - just remembering when the fifth postulate does or doesn't hold, but it's not considered acceptable to hold several sets of dogmas at once. Life of Pi provides an illustration of the controversy of such a stance (the main character is Hindu, Muslim and Catholic simultaneously and his brothers-in-dogmas don't like to share him with the competition).

I'm sure early geometers were much more religious about their axiom-dogmas than the modern mathematicians, but I have no proof.

• Axiom: Let us assume X is true. Dogma: X is true.
– SF.
Commented Jan 31, 2013 at 20:34
• Although I don't have a concrete example at hand, I would imagine that you can find instances of pairs of dogmas that contradict each other (within the same "theory") whereas pairs of axioms should not.
– Drux
Commented Feb 1, 2013 at 14:35
• Isn't "axioms within a theory shouldn't contradict each other" an axiom?
– artm
Commented Feb 1, 2013 at 14:59
• @SF. Great :) Possibly the most concise explanation ever! You should post that as an answer.
– DBK
Commented Feb 7, 2013 at 17:26
• @Drux: Axioms define the reality the theory is to describe, so if they define it in a self-conflicting way, the theory must work around that conflict. Take Lobachevsky's geometry which contains a seemingly self-conflicting axiom, and then the theory must bend the underlying space to satisfy it.
– SF.
Commented Feb 8, 2013 at 5:36

An axiom is something that is self-evidently true; it is so obvious that there is no controversy about it. In mathematics, you just have to accept some very basic notions in order to avoid circular reasoning. These can't be proven, but they can always (and often very easily) be observed.

Example from Euclid's Elements:

Common notions:

1. Things that are equal to the same thing are also equal to one another (Transitive property of equality).

2. If equals are added to equals, then the wholes are equal.

3. If equals are subtracted from equals, then the remainders are equal.

4. Things that coincide with one another equal one another (Reflexive Property).

5. The whole is greater than the part.

Or an example from propositional logic:

If:

• A is true
• B is true

Then

• A&B is true

A dogma refers to (usually a religious) teaching that is considered undoubtedly and absolutely true. It is something you accept without any direct observation; dogmas are accepted by faith only.

I should add that some people would say that there is no difference between axioms and dogmas, because 'self-evident truths' are in some sense based on faith; that is that you accept on faith that anything that seems obvious and self-evident is true. An interesting read on this subject is Wittgenstein's On Certainty. I also want to stress that I don't mean to say that an axiom is "better" than a religious dogma (or vice versa for that matter).

• Good answer, but I'm not so sure about axioms generally being obviously self-evident. Take the axiom of choice, for example: there is huge division in mathematics as to whether it's true or not, and many proofs are written based on a by-faith acceptance (or rejection) of said axiom. In this regard I suppose I'm one of those who thinks there isn't a real difference between axioms and dogma - except maybe context. Commented Feb 15, 2013 at 16:12
• @commando I accept your point. Not all axioms are self-evident, but I still think there is a difference between an axiom and a dogma. An axiom is only something you accept within a theory (self-evident or not); a dogma is far more pervasive. Whether I accept the axiom of choice doesn't change my life; whether I accept to dogma of Christian faith, for instance, will. Also,I don't think there have been any wars over which axiom is true, but there has been plenty of conflict over dogmas.
– Ben
Commented Feb 15, 2013 at 17:12
• That seems to be true but, at an advanced level, it's IMO wrong. For example, Newtonian mechanics is "self-evident" and may be called "axiomatic". But it's not true in 'relativistic' environments (near the speed of light, near black holes), for which you need Einsteinian mechanics. You can do calculations taking Newtonian physics as "axiomatic" even though they're false ("let's assume that Newton is correct, e.g. because relativistic effects are negligible..."). Similarly Euclidian geometry depends on "axioms" which seem to be self-evident and can be defined as true but aren't inherently true. Commented Oct 28, 2014 at 2:42
• The 'That' which started my previous comment was referring to your opening sentence: that "An axiom is something that is self-evidently true; it is so obvious that there is no controversy about it." Instead, an "axiom" is something that's unprovable: which you need to assume is true in order to use it as a basis for going on to prove other things which assume it: "A is axiomatic, therefore B". You'll usually choose 'useful' or 'seemingly self-evident' axioms. but that's a whole other story. Commented Oct 28, 2014 at 3:13
• I'd say "Then A&B is true" is something that defines & operator. Commented May 5, 2018 at 11:45

In religions, some (should be majority) people accept the existence of God by belief. while some minority of them accept God by observation (thru meditation, etc). By believing, the faith can be shaken. By direct experience (the perfect balance of mindfulness and concentration), it is just there, there is no doubt about it.

• "By direct experience... it is just there, there is no doubt about it." I disagree, hallucinations are not just there. Commented May 5, 2018 at 11:38
• An hallucination is not a direct experience. Here 'direct' should mean 'unmediated'. It should be noted that Buddhism explains the monotheistic God as misinterpreted meditative experience and thus like an hallucination, but the issue is subtle and this should not be seen as simple atheism. An experience is never false but our interpretation of it may be all over the place.
– user20253
Commented May 5, 2018 at 11:49
• Direct exp. is difficult topic. Here I give one easy example to show what direct exp. is and that it is not hallucination : After direct experience, the world seen is just exactly the same as before direct experience, there is no flying cars, talking animals, etc. It is just that some things that have not perceived or not clearly perceived before direct exp, (simply because they are being ignored) are now perceived more clearly and understood better. When things become clearer and understood better, that is Awakening (direct experience). Therefore it is different from hallucination.
– God
Commented May 6, 2018 at 14:58

When starting with a set of axioms, you might end up with a contradiction. This indicates that one of the axioms are wrong. You then figure out which one it is, and reject it. (This is a simplification, but sufficient in answering this question.)

When you are not allowed to reject the axiom even when you have successfully shown it to be false, the axiom you are not allowed to reject is now dogma.

• Not if the axioms are definitions. Commented Jul 13, 2017 at 18:43
• @ChristopherE, definitions are a subset of axioms in universal form (forall X forall P(Y): X is subset P(Y)). Commented May 5, 2018 at 11:39