The Theological Roots of Thought Experiments in the Middle Ages

Prompted by a fruitful exchange on the Facebook, here’s some historical notes on the roots of thought experiments.

Perhaps the most important event in the history of thought experiments comes in the surprising form of a condemnation of a specific style of natural philosophy – the Condemnation of 1277, issued by Etienne Templar. This condemnation had as its focus a number of Aristotelian propositions, all of which were taken to impugn on the power of God to do whatever He wanted (so long as it didn’t involve a logical contradiction), which included God’s inability to create multiple and different worlds from the actual world, the necessity of all things that happen in the actual world, and constraints on God’s ability to move the heavens in a rectilinear way.

An immediate consequence of the Condemnation was a focus on God’s power for ‘natural impossibilities’ – events with conditions that were impossible from within the received Aristotelian physics. Out of this focus developed two senses of the hypothetical: one concerned with defending Aristotle, the other with moving past him.

The former can be most clearly illustrated by Albert of Saxony:

‘In the fourteenth century, for example, Albert of Saxony, an influential scholastic arts master and natural philosopher, assumed the truth of the eternity of the world and also the existence of a fixed quantity of matter in the world. From these assumptions, he concluded that over an infinite time, this limited quantity of matter would have to furnish bodies for an infinite number of souls. In the course of an eternal period of time, the same matter might serve as the human body of a number of different souls. On the day of resurrection, however, when every soul receives its own material body, a finite quantity of matter would have to receive an infinite number of souls. This was a heretical state of affairs, because one body – indeed every body – would have to receive more than one soul. Albert’s response to this dilemma was typical for natural philosophers who had to contend with theological restrictions. He explains that “the natural philosopher is not much concerned with this argument because when he assumes the eternity of the world, he denies the resurrection of the dead.” Albert simply dropped the inconvenient theological consequences from his discussion but retained the eternity of the world for the sake of the argument. By such appeals and devices, medieval natural philosophers could assume the truth of almost any condemned proposition, provided that they did not proclaim it to be categorically or philosophically true.’ (Edward Grant, ‘The Foundations of Modern Science in the Middle Ages’, p. 80-81)

The more significant sense of the hypothetical, however, turned on God’s power to do anything short of a logical contradiction. This had the effect of encouraging speculation about the world and the way it could be, even though it was ‘naturally impossible’ given Aristotelian physics. The key point to note here isn’t that Aristotle was overthrown or subverted. By using God’s power as a vehicle for speculative natural philosophy, an important meta-counterfactual began to come into view: that the world could coherently be conceived in non-Aristotelian terms. Counterfactuals ‘according to the imagination’ soon became a hallmark of late medieval thought:

‘Natural philosophers actually devised an expression to epitomize this approach when they referred to such counterfactuals as secundum imaginationem, that is, “according to the imagination. The Condemnation of 1277 played a significant role in generating counterfactuals. Many of the condemned articles compelled the acknowledgement of God’s absolute power to do whatever he pleased short of a logical contradiction. Examples of counterfactuals that were derived from the Condemnation of 1277 include the possibility of other worlds, vacua within and beyond our world, and the possibility that God might move our world with a rectilinear motion. In each of these examples, medieval natural philosophers sought to derive consequences within an assumed framework of Aristotelian physics, even though what they initially assumed was impossible in Aristotle’s system. What emerged were a series of interesting speculations, or, as we might say, thought experiments, in which certain Aristotelian principles were challenged and, to some extent, subverted.’ (p. 147-148)

From these counterfactuals emerged new conceptualizations of the world, many of which would be inherited by the early moderns and which would give impetus to the scientific revolution. By clearing the space for non-Aristotelian concepts of the world to be coherently conceived, the groundwork was laid for the assumptions that would drive the scientific revolution:

‘A significant natural impossibility that derived from the condemnation of 1277 involved Article 49, which made it mandatory after 1277 to concede that God could move the world rectilinearly, despite the vacuum that might be left behind. More than an echo of this imaginary manifestation of God’s absolute power reverberated through the seventeenth century. When Gassendi declared that “it is not the case that if God were to move the World from its present location, that space would follow accordingly and move along with it,” he was using the supernatural motion of the world as a convenient support for his belief in the absolute immobility of infinite space. As spokesman for Isaac Newton, Samuel Clarke (1675-1729), in his dispute with Leibniz, also defended the existence of absolute space when he argued that “if space was nothing but the order of things coexisting [as Leibniz maintained]; it would follow that if God should remove the whole material world entire, with any swiftness whatsoever; yet it would still always continue in the same place.” Finally, the power of counterfactuals is nowhere more impressively illustrated than in the principle of inertia, which Newton proclaimed as the first law of motion in The Mathematical Principles of Natural Philosophy (1687): “Every body continues [or perseveres] in its state of rest, or of uniform motion in a right line, unless it is compelled to change that state by forces impressed upon it.”  In medieval intellectual culture, where observation and experiment played negligible roles, counterfactuals were a powerful tool, because they emphasized metaphysics, logic and theology, the very subjects in which medieval natural philosophers excelled.’ (197)

Intellect and Reality

So, Kant basically ascribed to the mind a real creative power – things are understandable only insofar as they brought under or within the conditions of sensibility. This I’ll call the active power of the mind, since the categories for understand-ability are supplied by the mind. Now, as I said before, that the mind is in fact an active and not merely passive factor in our knowledge of the world is a fairly incontestable point, but thinking more on this topic led me to think about the intellect in general.

Aristotle held that the intellect was divided into the active (a) an the passive (p). p is the part of the intellect which receives data from the material world, while a acts as a kind of formal cause on the sensory data, forming ideas and thoughts with determinate structure. Aquinas basically held this same view, but tweaked it a bit: p still receives sensory data, but a grasps the form, which it abstracts, from the sensory data (Scotus disagreed with this and believed that the object of the intellect wasn’t the essence or quiddity of a thing, but being itself, but for right now I won’t go into that – for a bit more on that topic, see this post). So you basically have a concept of the intellect (and there’s a lot more to it, with categories like quality and whatnot, but this suffices for present purposes) where it is both passive and active in its knowledge of the world.

The medievals had this great concept: the fit of the intellect to reality. There is some kind of match between the intellect and reality, or the world or whatever you like to call it. Our cognitive faculties are able to allows us to know things about the world – of course, the medievals attributed this to the fact that God had created the world in this way (which I also happen to believe), but whether or not one believes that such a fit is a product of divine creation, it certainly seems that there is in fact a fit between our intellect, or our cognitive faculties and the world in which we live.

This brings me from the medievals ( in my mind, all roads in philosophy lead to the medievals) back to Kant. Where Kant made the mind purely active, the medievals, and the classical tradition as a whole, saw the mind as both active and passive – passive in that there is a world which acts upon our minds, and active in that in some way, the mind acts as a formal cause upon the sensory data received by the mind to impose a determinate form upon the data, either by abstracting the form or essence from the data or by some other means.

Nature, Grace and Predestination in the 9th Century

A preliminary to any discussion of predestination in the 9th century has to be the concepts of nature and grace. As I mentioned in a previous post, the distinction between nature and grace basically ran like this (the references here will all come from Pelikans’s ‘The Growth of Medieval Theology’):

Augustine: nature = supported by grace, after the fall, grace is taken away. Nature without grace can only do evil.
Pelagius = nature is grace – righteousness is part of the original nature of man. Grace is immutable in the person.

It was the Augustinian viewpoint that dominated the medieval tradition – free will, for example, was seen to only be free in any meaningful sense if it was supported by grace. Bear this in mind as the background and underlying presuppositions of this entire debate, even though it’s not directly referenced.

Now, generally, there are two main ways of thinking about predestination: either God picks by means of decree some to be saved, or God picks based on His foreknowledge of what people would freely do. A key point in Augustine, who was basically the ender of disputes in the medieval period, was this, that God acted…

‘…for the damnation of those whom he had justly predestined to punishment and for the salvation of those whom he had kindly predestined to grace.’ (p. 81

The latter originated with a guy named Hincmar, who turns out to be another guy named Gottschalks arch enemy. Hincmar said that God foreknew that…

‘…some, through the freedom of the will assisted by grace, would be good…’ (86)

…and these were the people he predestined to salvation. This is single predestination. God predestines based on foreknowledge who goes to heaven, passing over the reprobate.

Gottschalk based his double predestination heavily on his idea of God’s impassibility:

‘”I believe and confess that God, omnipotent and unchangeable, has foreknown and predestined”: so Gottschalk opened a confession of his faith. The conclusion of another statement of faith was an apostrophe extolling the transcendence of God beyond time and beyond change. If God had not foreordained the damnation of the devils and the wicked, they could not be damned; for “if he does something which he has not done by predestination, he will simply have to change,” which was blasphemous.’ (p. 85)

An area of dispute was the distinction between God’s foreknowledge and predestination – did the one impose necessity on the other? Did it even make sense to talk of ‘fore’ knowledge in God? This was an area of intense discussion – but for the sake of brevity I’ll pass over it, noting the two obvious answers: either (a) it did impose necessity, or (b) it didn’t, for one reason or another.

To breeze through a pretty lengthy and subtle debate: both sides believed that they were teaching the correct doctrine, and each believed the other to be a heretic. Both were able to find support in Augustine, and both had patristic support as well as contemporary followers. The most pertinent for modern discussions is the emergence of this viewpoint:

‘This statement of Paul’s, (that God desired all men to be saved), the predestinarians had to admit, was “extremely perplexing and  much discussed in the writings of the holy fathers and explained in many different ways”. Therefore its interpretation was “not to be settled precipitately, but very cautiously”. They rehearsed Augustine’s various attempts to circumvent the text’s affirmation of the universal salvific will of God. From the use of the identical word ‘desires’ in 1 Timothy 2:4. “who desires all to be saved”, and in Romans 9:18, “He has mercy upon whoever he desires,” Gottschalk strove to demonstrate that “truly God has not in way desired to save with eternal salvation those whom, as Scripture testifies, he hardens.” The “all men” in the text must mean “all men who are saved” rather than “all men” in general.’ (p. 90)

This viewpoint opened up all kinds of other questions: how effective was the death of Christ in securing redemption? We have as responses some now classic answers: on the one side, God could be accused of injustice if his son died for only for some and not others. On the other side, the blood of Christ would be seen as being wasted if it was shed for those who were not saved. Both of these were developed in intricate detail by their supporters.

To sum up: the contemporary debate, usually had between Calvinists and Arminians, over the scope of redemption, predestination and God’s foreknowledge, can be seen reaching all the way back to the 9th century – and, oddly enough, it seems that the answers have basically remained the same ever since.

As a postscript: the real issue here is the idea of externalism in regards to salvation, which Barth/Torrance subjected to pretty withering criticism in their writings.


I’m doing some reading on the medieval development of the idea of natural rights, as opposed to the notion that they developed as a result of secular though – fascinating subject. Nicholas Wolterstorffs book ‘Justice; Rights and Wrongs’, develops the theory further, that the idea of rights is found in the Old and New Testament. Some more posts (probably brief posts) on the subject will probably be forthcoming.

Musings on Medieval Philosophy

The middle ages were such  rich time of learning – the Scholastics in particular fascinate me. People like Anselm, Aquinas, Ockahm, Duns Scotus, Abelard and many, many others really were part of one of the richest intellectual traditions in history, a tradition that continues on to this day. What I find to be very interesting is how much we’ve inherited, culturally speaking, from the middle ages – politically, philosophically, theologically, ethically, etc. What a wonderful world to spend time learning about – here’s a couple resources that have been invaluable to me: