# Agrippa's Trilemma and Foundationalism **URL:** \ **Category:** General Philosophy\ **Created:** [June 22, 2026, 10:55pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451 "2026-06-22T22:55:58Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![Jay](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/jay/32/206_2.png) [@Jay](https://www.thephilosophyforum.com/u/Jay)\ **Post date:** [June 27, 2026, 10:24pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/41 "2026-06-27T22:24:29Z")
> [@TheEudemian](#): > > Justifying a belief as true is the same as justifying what is true because both demonstrate what is true. I don’t think so. To “justify what is true” seems like an odd phrase, but if you merely mean “demonstrate or show why it is true,” I suppose that’s all right. Whereas, when I justify my _belief_ about X, I am explaining why _I_ claim it to be correct. That can go well or badly without affecting the truth of the statement, or its correspondence (or lack of it) to X. The ordinary usage to refer to here would be, “I was fully justified in believing X, but as it turned out X wasn’t true.” Unless you think that’s incoherent? Some philosophers want “justify” to mean something very technical. None of this is very important, I just wanted to be sure I hadn’t inadvertently misrepresented the question as being about truth rather than belief. ---
**Author:** ![Banno](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/banno/32/55_2.png) [@Banno](https://www.thephilosophyforum.com/u/Banno)\ **Post date:** [June 27, 2026, 10:42pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/42 "2026-06-27T22:42:23Z")
> [@TheEudemian](#): > > If you are stipulating that equality is ‘to be the same’ then you are holding an axiom of equality; exactly because you have no justification for it being true. x=x is not _assumed_ in the way an axiom is assumed; it could not be false. An axiom is a proposal that might be false, but is taken as being true; for example, that only one line parallel to another given line passes through a given point. To see this, consider the negation of each. ~(x=x) is a contradiction, but assuming more that one line may be parallel to another given line and pass through a given point gives us non-Euclidean geometry. it’s not uncommon for a group of different ideas hereabouts to be run together. These are, that x=x, Leibniz’s Law, and a few curious Aristotelian metaphysical notions of essence. Folk will slide between these three distinct notions so as to re-cast identity as essence. Better to keep them separated and have folk argue their case clearly. x=x is a tautology. Leibniz’s Law tells us about the consequences of a=b. Essentialism presumes that a thing is a thing because of some mooted essential properties. These are three different proposals, two of which concern logic, the third, metaphysics. If you want to do the latter, at least recognise that it is not a point of logic. ---
**Author:** ![Banno](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/banno/32/55_2.png) [@Banno](https://www.thephilosophyforum.com/u/Banno)\ **Post date:** [June 27, 2026, 10:45pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/43 "2026-06-27T22:45:35Z")
> [@Jay](#): > > None of this is very important It’s not uncommon for folk to fail to differentiate something being true from something being believed true. So your point is well worth making. ---
**Author:** ![Leontiskos](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/leontiskos/32/712_2.png) [@Leontiskos](https://www.thephilosophyforum.com/u/Leontiskos)\ **Post date:** [June 28, 2026, 12:34am UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/44 "2026-06-28T00:34:19Z")
> [@Banno](#): > > It’s not uncommon for folk to fail to differentiate something being true from something being believed true. I mean, that’s literally what you have been doing with your “T-sentence” approach to ethics. [For example](https://www.thephilosophyforum.com/t/i-am-a-moral-nihilist/1218/778). ---
**Author:** ![Banno](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/banno/32/55_2.png) [@Banno](https://www.thephilosophyforum.com/u/Banno)\ **Post date:** [June 28, 2026, 12:40am UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/45 "2026-06-28T00:40:08Z")
No, Leon. Tarski sentences are not about belief. ---
**Author:** ![Leontiskos](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/leontiskos/32/712_2.png) [@Leontiskos](https://www.thephilosophyforum.com/u/Leontiskos)\ **Post date:** [June 28, 2026, 12:48am UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/46 "2026-06-28T00:48:10Z")
Fair warning: I’ve put you back on ‘ignore’. You’ve proven beyond a doubt that you are not a serious poster. ---
**Author:** ![Leontiskos](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/leontiskos/32/712_2.png) [@Leontiskos](https://www.thephilosophyforum.com/u/Leontiskos)\ **Post date:** [June 28, 2026, 12:49am UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/47 "2026-06-28T00:49:34Z")
For the Aristotelian-Thomistic view on this question, see my old post [here](https://archive.thephilosophyforum.com/discussions/14725-speculation-eternalism-and-the-problem-of-evil.html#comment-849472). That two-part thesis from Laval is the best source I know of on this topic, although I have not studied the topic in great depth. ---
**Author:** ![Banno](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/banno/32/55_2.png) [@Banno](https://www.thephilosophyforum.com/u/Banno)\ **Post date:** [July 2, 2026, 9:35pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/48 "2026-07-02T21:35:46Z")
The better reply is found in @Sam26’s various threads on “On Certainty”. Any doubt rests on a background of certainty, even if in the language in which the doubt is expressed. We are already in a communal structure that takes some things as foundational; one can doubt anything, but not everything. ---
**Author:** ![Leontiskos](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/leontiskos/32/712_2.png) [@Leontiskos](https://www.thephilosophyforum.com/u/Leontiskos)\ **Post date:** [July 2, 2026, 11:26pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/49 "2026-07-02T23:26:51Z")
> [@Banno](#): > > The better reply is found in @Sam26’s various threads on “On Certainty”. Sam’s Wittgenstenian confusion on these topics is definitely instructive. See my archived reply to his approach [here](https://archive.thephilosophyforum.com/discussions/15986-tpf-essay-wittgensteins-hinges-and-g%C3%B6dels-unprovable-statements.html#comment-991925), which is related to this OP. ---
**Author:** ![TheEudemian](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/theeudemian/32/1304_2.png) [@TheEudemian](https://www.thephilosophyforum.com/u/TheEudemian)\ **Post date:** [July 8, 2026, 10:59pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/50 "2026-07-08T22:59:56Z")
> [@Jay](#): > > I’m not sure I understand the difference between this sense of “dogma” and the other kind. Are you saying that there _are_ infallible sources of “historical dogma”? ‘Dogma’, in the historical sense for Christianity, is truth revealed by an infallible source (viz., The Holy Deposit): it is not a belief that is assumed to be true. In modern times, we also use the term ‘dogma’ to mean that latter sense; but you equivocated them. In the OP, I was using ‘dogma’ in the modern sense (of an assumed truth); but you responded about religious dogmas which are not assumed truths. ---
**Author:** ![TheEudemian](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/theeudemian/32/1304_2.png) [@TheEudemian](https://www.thephilosophyforum.com/u/TheEudemian)\ **Post date:** [July 8, 2026, 11:03pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/51 "2026-07-08T23:03:05Z")
> [@Scorpion](#): > > I was applying the skeptic’s definition, dogma as the non-evident. Meaning is fluid, dogma can also mean some kind of tenet or belief that’s immune to criticism/alteration. Fair enough. > [@Scorpion](#): > > But it is impossible, right? I would say that this adds to our woes. It feels like you’re pleasurably ignoring the infinite in infinite regress. 😃 It would be impossible for a finite faculty to give the totality of reasons for any justification; but it would be technically a valid chain of justification if the finite faculty of reason is traversing an infinite chain of valid reasons. You wouldn’t be able to critique this view to the point of successfully demonstrating an infinite chain of justification leads to unjustified beliefs exactly because you are not challenging the legitimacy of the justification itself: you are, rather, just commenting on the impossibility of a finite faculty traversing the whole infinite chain in time. ---
**Author:** ![TheEudemian](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/theeudemian/32/1304_2.png) [@TheEudemian](https://www.thephilosophyforum.com/u/TheEudemian)\ **Post date:** [July 8, 2026, 11:04pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/52 "2026-07-08T23:04:22Z")
> [@Jay](#): > > The ordinary usage to refer to here would be, “I was fully justified in believing X, but as it turned out X wasn’t true.” That’s fair: I agree. ---
**Author:** ![TheEudemian](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/theeudemian/32/1304_2.png) [@TheEudemian](https://www.thephilosophyforum.com/u/TheEudemian)\ **Post date:** [July 8, 2026, 11:06pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/53 "2026-07-08T23:06:01Z")
> [@Banno](#): > > x=x is not _assumed_ in the way an axiom is assumed; it could not be false Your belief that ‘x=x cannot be false’ is what is in question here: not ‘x=x’. Either your belief here is assumed, justified with an infinite chain of reasons, or bottoms out at a justified reason. Which is it? ---
**Author:** ![TheEudemian](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/theeudemian/32/1304_2.png) [@TheEudemian](https://www.thephilosophyforum.com/u/TheEudemian)\ **Post date:** [July 8, 2026, 11:07pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/54 "2026-07-08T23:07:48Z")
Thank you! I’ll read through that thread when I have a moment. ---
**Author:** ![TheEudemian](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/theeudemian/32/1304_2.png) [@TheEudemian](https://www.thephilosophyforum.com/u/TheEudemian)\ **Post date:** [July 8, 2026, 11:09pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/55 "2026-07-08T23:09:04Z")
I’m sorry, but you aren’t contending with Agrippa’s Trilemma by claiming we cannot absolutely know anything: that’s simply irrelevant. This trilemma is talking about _justification_ which does require absolute certainty. ---
**Author:** ![Banno](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/banno/32/55_2.png) [@Banno](https://www.thephilosophyforum.com/u/Banno)\ **Post date:** [July 8, 2026, 11:47pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/56 "2026-07-08T23:47:46Z")
As explained, x=x is a stipulation. As such it is not the sort of thing that can be false. To suppose it false or to ask it to be justified is to misunderstand the use of “=” or of “x”. If an axiom is understood as a substantive presumption that might have turned out to be false, then _x = x_ is not an axiom in that sense. Nor is it properly described as an assumption. Rather, it is constitutive of the symbolism itself: once “=” is introduced as the identity relation, and “x” as a variable, _x = x_ is fixed by those conventions. It is not a claim that stands in need of evidence or justification, but part of what makes the symbolism function as it does. ---
**Author:** ![Banno](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/banno/32/55_2.png) [@Banno](https://www.thephilosophyforum.com/u/Banno)\ **Post date:** [July 8, 2026, 11:57pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/57 "2026-07-08T23:57:57Z")
I’m not sure you followed what was said in that post. I am certainly not claiming that “we cannot absolutely know anything”. We do know things. Quite a bit, actually. But further: are you reading this post now? I don’t see how you could sensibly write a reply to this post without it being true that you read it, at least to some degree. It seems then that in order to reply to my post, you must grant some degree of truth to how things are - that there is a post to which you are replying. Participation in life requires taking some things as granted. That includes doubt. To doubt something one must take other things as granted. ---
**Author:** ![Jay](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/jay/32/206_2.png) [@Jay](https://www.thephilosophyforum.com/u/Jay)\ **Post date:** [July 9, 2026, 12:41am UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/58 "2026-07-09T00:41:56Z")
> [@TheEudemian](#): > > ‘Dogma’, in the historical sense for Christianity, is truth revealed by an infallible source (viz., The Holy Deposit): it is not a belief that is assumed to be true. In modern times, we also use the term ‘dogma’ to mean that latter sense; but you equivocated them. In the OP, I was using ‘dogma’ in the modern sense (of an assumed truth); but you responded about religious dogmas which are not assumed truths. Thanks, that’s informative, though in fairness I didn’t equivocate them; I was doing my best to _un_equivocate them by asking into the (possible) difference. Another poster raised the “religious dogma” question, to which you responded. ---
**Author:** ![Scorpion](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/scorpion/32/875_2.png) [@Scorpion](https://www.thephilosophyforum.com/u/Scorpion)\ **Post date:** [July 9, 2026, 2:08pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/59 "2026-07-09T14:08:47Z")
> [@TheEudemian](#): > > It would be impossible for a finite faculty to give the totality of reasons for any justification; but it would be technically a valid chain of justification if the finite faculty of reason is traversing an infinite chain of valid reasons. You wouldn’t be able to critique this view to the point of successfully demonstrating an infinite chain of justification leads to unjustified beliefs exactly because you are not challenging the legitimacy of the justification itself: you are, rather, just commenting on the impossibility of a finite faculty traversing the whole infinite chain in time. I’m simply wondering why it’s the infinite regress and not the issue of contingency. ---
**Author:** ![Scorpion](https://yyz1.discourse-cdn.com/flex007/user_avatar/www.thephilosophyforum.com/scorpion/32/875_2.png) [@Scorpion](https://www.thephilosophyforum.com/u/Scorpion)\ **Post date:** [July 9, 2026, 2:15pm UTC](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451/60 "2026-07-09T14:15:06Z")
@Banno @TheEudemian x = x is a proposition. It would require some sort of clarification. Wikipedia, where I get most of my information from, has an entry on the laws of logic but it’s vague and unclear. [Previous page](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451.md?page=2) [Next page](https://www.thephilosophyforum.com/t/agrippas-trilemma-and-foundationalism/1451.md?page=4)