How much more “incompatible” was rationalism with Catholicism compared to Protestant christianity?

Of course everyone learned in high school that the enlightenment was in direct opposition to Catholic dogma. In the 18th century it relentlessly attacked and ridiculed the Catholic Church, we all know enough examples – so this question may sound a bit naive.

The difference to me seems:

Rationalism has always been

  • completely incompatible with Catholicism
  • an important part of Protestant thought

But… the curious thing is: it starts right with the early enlightenment, with someone as as careful as the Catholic Descartes (when it comes to faith, he sounds more like a spokesman for the Middle Ages). His works ended upon the Index (stayed there till its abolition in the 20th century) and were also banned by royal decree… while Leibniz was revered in Protestantism.

I wonder if I overstate things?

Were there any instances in history were rationalism was tolerated by the Catholic Church? Did any other rationalist philosopher after Descartes make an attempt to reconcile his philosophy with Catholic faith?

Or were there were major conflicts between Protestant authorities and a Protestant rationalist (like Descartes vs. the Catholic Church)?

Edit (some clarification): I do understand rationalism as the Enlightenment philosophy that regards reason as the chief source and test of knowledge. Empiricists are obviously a part of the Enlightenment, too, but afaik they didn’t feel – like rationalists – to reserve an important place for God in their systems.

Empiricists could either chose to set the issue of God aside (like Locke (?)) and avoid controversy or be an infuriating skeptic (like Hume). For Empiricists it seems clear that they couldn’t get a positive reaction by Christians (that is, only something between neutral and hostile) – Protestant and Catholic alike.

Many rationalists OTOH, like Descartes and Leibniz, used God aggressively in their philosophies. So one could expect a positive reaction by Christians, because they gave God an important place and somewhat synthesized theism with the early modern philosophy. But this positive reaction seems solely a Protestant thing. The Catholic church didn’t want to hear anything of it.

  • 2
    Which 'Protestant authorities' are you referring to specifically? There is a wide gamut of authorities in Protestantism. the rationalism of the Renaissance, the start of the age of modernity, is not the same rationalism of Protestant thought. You are conflating the word rationalism used in two different contexts. The rationalism of the Renaissance rejected the 'deus ex machina' and looked for causes within the thing itself. Although the Protestant reformation occurred in and around the same time period, it is in no way related to the Renaissance, Oct 5, 2019 at 23:48
  • @SwamiVishwananda as the Protestant Church was organized, the secular ruler was usually also the head of the church. There were also protestant theologians which had some authority. I mean those. Regarding my supposed conflation of rationalism see the edit.
    – viuser
    Oct 6, 2019 at 16:06

1 Answer 1


To suggest a different perspective, Whitehead writes the following: (page 8-9)

The Reformation and the scientific movement were two aspects of the historical revolt which was the dominant intellectual movement of the later Renaissance. The appeal to the origins of Christianity, and Francis Bacon's appeal to efficient causes as against final causes, were two sides of one movement of thought....

....It is a great mistake to conceive this historical revolt as an appeal to reason. On the contrary, it was through and through an anti-intellectualist movement. It was the return to the contemplation of brute fact; and it was based on a recoil from the inflexible rationality of medieval thought.

Protestantism could be viewed as a rejection of the rationalism of Catholicism desiring to go back to the origins of Christianity for the brute facts in the Bible rather than relying on Scholastic or Catholic authority.

Regarding Descartes, Wikipedia offers a hint as to why he may have had trouble with Catholic authorities:

In shifting the debate from "what is true" to "of what can I be certain?," Descartes arguably shifted the authoritative guarantor of truth from God to humanity (even though Descartes himself claimed he received his visions from God)—while the traditional concept of "truth" implies an external authority, "certainty" instead relies on the judgment of the individual.

If that best describes the events then rationalism (and the external authority grounded on it) characterized Catholicism while the Protestant revolt modeled itself more on a scientific pursuit through individual judgment of the brute facts each believer found in the Bible.

Whitehead, A. N. Science and the Modern World. Retrieved from Internet Archive on October 5, 2019 at https://archive.org/details/alfrednorthwhiteheadscienceandthemodernworld1997/page/n19

Wikipedia contributors. (2019, October 5). René Descartes. In Wikipedia, The Free Encyclopedia. Retrieved 19:33, October 5, 2019, from https://en.wikipedia.org/w/index.php?title=Ren%C3%A9_Descartes&oldid=919735446

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