QuestionsShould we believe without proof?The Son of God died: it is credible, because it is unfitting
Should we believe without proof?Faith goes beyond

The Son of God died: it is credible, because it is unfitting

"Credo quia absurdum" (a distorted formula); "What has Athens to do with Jerusalem?"

Tertullien 155 · 220Latin-writing Christian author: Christian faith has no need to pass through philosophy.
See profile
What it claims

The Christian message is worthy of belief without philosophy, which is neither its source nor its condition: its very strangeness is a reason to believe it.

Why

What people would not have invented, because it seems absurd to them, deserves to be believed.

The same idea through history
Tertullien206In On the Flesh of Christ (early 3rd century, dating uncertain), against Marcion, who denied that Christ had a real body: what looks shameful and unfitting in the cross is, he says, what makes the story credible.
Søren Kierkegaard1846Under the name Johannes Climacus, he makes faith a risk: being a Christian depends on the believer's "how", which fits only the "absolute paradox". Another age, another language, a similar idea: faith is not deduced from a proof.
In short

"The Son of God died: it is credible, because it is unfitting" is an argument by Tertullien (On the Flesh of Christ, 5; The Prescription against Heretics, 7, 206) on the question "Should we believe without proof?" (answer: faith goes beyond). Its claim: The Christian message is worthy of belief without philosophy, which is neither its source nor its condition: its very strangeness is a reason to believe it. According to AskPhilosophy's logic check (Z3 solver), the argument is valid only if one grants a premise the author leaves unstated (P4). AskPhilosophy presents 2 objections, 2 of them with a documented reply, and the original text behind each premise, checked word for word.

On the Flesh of Christ, 5; The Prescription against Heretics, 7
Valid with an implicit premise

Tertullian (Carthage, about 155-220) is often summed up by the phrase "I believe because it is absurd" (credo quia absurdum). He never wrote it. It is a late distortion: according to the historian Peter Harrison, a close form appears in 1643 in Thomas Browne, and it became a slogan of faith against reason in the Enlightenment. What Tertullian actually writes, in On the Flesh of Christ (5), is more precise. He answers Marcion, for whom Christ had no real body, because a God who is born, crucified and dies would be unworthy of God. Tertullian accepts this shame: "The Son of God died: it is by all means credible, because it is unfitting (ineptum, that is, out of place, silly). He was buried and rose again: it is certain, because it is impossible." Scholars do not read this as a rejection of all reason. Robert Sider (1980), following James Moffatt (1916), sees an argument from probability taken from Aristotle's Rhetoric: a story so shocking cannot have been invented by men, and that is a reason to believe it. In another work, The Prescription against Heretics (7), Tertullian asks the question that became famous: "What has Athens to do with Jerusalem?" For him philosophy is the mother of heresies, and whoever has received the Gospel has no further need of "curiosity" or inquiry. Here is the thesis in its strongest form: Christian faith stands on its own, without philosophy having to ground it or judge it.

P1The Christian message announces a God who was crucified, died, and rose again. To the wisdom of the world, this is shameful, unfitting (ineptum) and impossible.
P2Between philosophy (Athens, the Academy) and Christian faith (Jerusalem, the Church) there is nothing in common: faith does not come from philosophy, and philosophy is the source of heresies.
P3For whoever has received the teaching of Christ and the Gospel, no further philosophical inquiry is needed.
P4 · implicit premiseWhat men would not have invented, because it seems unfitting to them, is worthy of belief (argument from probability, as read by Moffatt and Sider).
Therefore the Christian message is worthy of belief without philosophy, which is neither its source nor its condition: its very strangeness is a reason to believe it.

click a premise to reject it

If you accept every premise, logic forces you to accept the conclusion. So the debate is about the premises.
Checked by a logic solver: the premises cannot all be true while the conclusion is false.
Without the implicit premise: Without P4, the computer finds a case where the message is unfitting, does not come from philosophy and does not need it, without being worthy of belief: the conclusion does not follow.
P1, P2 and P3 give three elements: the message looks unfitting to the world, does not come from philosophy, and does not need it. To conclude that the message is worthy of belief, P4 is needed: what looks unfitting was not invented, so deserves trust. Critics mostly discuss P4: is an improbable story more credible, or only more improbable?
Analogy. A witness tells a story that covers him with shame and helps nobody. If he had made it up, he would have arranged it to his advantage. The oddness of the story argues, says Tertullian, for its authenticity.

Objections

2

Each objection is a conversation: click to see who replies and where the debate stands.

A
Augustine attacks premise 3

For Augustine, believing and understanding do not exclude each other: one must believe in order to understand, and understand a little in order to believe. He concludes: "Understand my word in order to believe, and believe the word of God in order to understand." Sermon preached in the early 5th century.

a defender replies
see the argument
No reply possible: objection raised after the author's death (220).
R
Robert D. Sider defender of the argument · 1980
Sider argues that Tertullian is not the enemy of reason he is imagined to be: in this passage he follows an argument from probability (Aristotle, Rhetoric II, 23), where the oddness of a story is a reason to believe it, and he uses the word fides in the sense of "token of evidence". He ranks him among the rationalists, not the fideists.
Where the debate stands (our summary)Our summary: scholars read Tertullian as an author who reasons, not as an enemy of reason. The basic disagreement remains: should one, like Augustine, seek to understand what one believes, or, like Tertullian in the Prescription, treat inquiry as closed once the Gospel is received?
Thomas Aquinas 1259 · attacks premise 1

Aquinas replies that only the false is opposed to the true. So the truth of faith cannot be opposed to the principles that reason knows naturally (Summa contra Gentiles, I, 7).

a defender replies
see the argument
No reply possible: objection raised in 1259, after the author's death (220).
Søren Kierkegaard (Johannes Climacus) defender of the argument · 1846
Under the name Johannes Climacus, Kierkegaard argues that faith requires risk: it is the contradiction between the believer's infinite passion and objective uncertainty. If I could grasp God objectively, I would not believe.
see the argument
Where the debate stands (our summary)Our summary: everything turns on the meaning of "impossible". For Aquinas, faith goes beyond reason without contradicting it. For Tertullian and Kierkegaard, faith keeps a scandalous side that reason cannot absorb, and this is what makes it a risk. Basic disagreement: can reason judge what is worthy of belief?
What today's voices say
Defend it
Slavoj ŽižekHe calls Tertullian "my hero" and "not irrationalist": real belief cannot rest only on objective reasoning, there must be a moment of absurdity in it.