1.4 Reason in medieval thought

Against the background of the medieval perspective of things striving to follow the implications of their nature, reason is understood as the guide which tells human beings how to behave so as to fulfil their true nature - or, in Danby's formulation, how to obey the laws of Nature.

The scholastic conception of 'reason' is superficially all one with the way of thinking of the Moderns. Reason is the means by which a person starts from understanding one thing and moves to acquire an understanding of another.

But what is understood by 'understanding' changes dramatically with Modernity.

For Aquinas, understanding is sharing a form. For the Moderns it fissiparates, with none of its meanings to be equated with the Thomist.

What exactly was 'sharing a form' and how did Aquinas arrive at the idea that this is what understanding was?

Intellect was a key notion for Aquinas, and for him intellect seems to have been the capacity for the type of thought that is distinctive of human beings (ie, according to Kenny, 'the kind of thinking which finds expression especially in language' - Kenny, AoM, p. 41) There is no word in English to cover exercise of this capacity. (Latin has 'intelligere'.) 'Understand' covers some applications of 'intellegere' (the dispositional applications) though not others.

So to understand is to exercise the capacity for distinctively human thought. Perhaps at least we can say, with a regretted element of vagueness: what Aquinas is theorizing about in discussing the operation of the 'intellect' is the sort of thinking we are engaging in when our thought has the sort of sophistication or complexity of our talk.

And his theory is that the exercise of the intellect involves its coming to share the form of the thing thought about.

In advancing this theory, Aquinas encounters the following problem. there are no forms independently of the individual things that embody them (Aquinas follows Aristotle pace Plato). The senses deal only with particular things. How then can a person have a thought which is 'general'? This is the question which Kenny at least thinks arises for Aquinas.

Is there a problem here?

Aquinas thought so, because having a thought involved sharing a form, and if you had a thought which was not about a particular X or particular Xs generally (eg dogs are never more than 7 ft high), there seems to be no form to share.

The 'solution' to this problem, proposed by Aristotle and adopted by Aquinas, was to conclude that somehow the thinker had to be making a general form out of a particular one. He proposed that one part of the intellect had to be doing this. It was called the 'agent intellect'.

We mustn't forget that it was part of the Aristotelian conception that a particular thing's form was in fact that which made that particular thing a thing of a particular sort. The form embodied in a particular thing was what made that package of blood and bones a horse - a thing of the horse kind. So forms in Aristotelian thought addressed an aspect of the 'problem' of generality.

It's difficult to get a clear picture of how Aquinas envisaged the agent intellect doing its work. But - this is the sense of Aquinas' discussion surely - do its work it must, or we could never have thoughts with any generality to them.

What he says is that the agent intellect 'abstracts' from the form of a particular thing 'species', and it is these 'species' which are graspable by the intellect (exercising its remaining powers).

Making objects in the world thinkable has a parallel in the effect of light making a colour visible. 'One can think of the agent intellect as like the lantern a miner carries in his helmet, casting the light of intelligibility upon the objects a human being encounters in his [sic] progress through the mysterious world.' (Kenny, AoM, p.47.)

So even if the characterization of reason as that which takes you from one understood thing to another does not in itself sound alien, when one comes to terms with what 'understanding' amounted to in Thomist thought, the contrast with Modern thought is stark.

The distinctiveness of this conception of reason is highlighted when you contrast it with later perspectives. It is very different from the way of thinking which emerges in the 17th Century. Reason comes then to be seen as a tool, a tool which allows us to make correct inferences, to move from given premises to any conclusion that they support.

The premises don't even need to be true: reason discerns the legitimacy of the move, without commenting on the starting point.

You remember the point elementary logic texts make much of: there is a vital distinction between truth and validity.

We can reason correctly that

but that tells us nothing about the truth of the premise that no swans are black. The reasoning is absolutely correct, though the conclusion reached is wrong.

You may have come across the discussion of reason and its role in guiding behaviour that we find in the Modern David Hume:

Reason on its own gives us no guidance over what we ought to do: it is our desires that constitute our goals. Reason only comes in to help us see what we should do if we desire to do this or that.

This is the new sense of "reason" at work, and it gets established with the new science.

(There is a monumental attempt to restore reason as a guide to the ends human beings should pursue at the end of the 18th Century when what became known as the Romantic Movement tried to check the all-conquering advance of science. It was Kant, heralding this movement, who paradoxically tried to construe reason as a 'prompting of the heart', pointing us along the right path. I try and explain this here. I myself don't see that the attempt was successful. I think we still work essentially with the concept of reason propounded by the early Moderns (and by Locke in particular).)

But in the medieval period, "reason" does have to do with truth. It discerns the truth about our nature, and to an extent the nature of other creatures. It discerns for us our aim, what the end of our action should be. It tells us what we ought to do.

The Modern conception of nature is different.

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