[4.18.7] William Ockham on Supposition and Sciences

William Ockham (1285-1349 AD), in the treatise Commentary on the Sentences of Peter Lombard writes about the relationship between types of supposition and types of sciences:

  • Propositions (sentences) are made up of terms.
  • Terms in a proposition refer to other terms – the suppositum (or supposita); this relation is called supposition. The supposition of a term always occurs in a propositional context and can be entirely different from its signification (see [4.0.1]).
  • The relation between the term and the suppositum in the propositional context is called supposition (reference).
  • Ockham defines three kinds of supposition: personal, simple, and material.
  • For Ockham, science is a collection of true propositions. These propositions shouldn’t exclusively be about (1.3.10) universal knowledge.
  • “Traditionally, there were three kinds of sciences people distinguished: (a) the so called ‘real’ sciences: physics, metaphysics, and mathematics; (b) the so called ‘rational’ science: logic; and (c) ‘grammatical’ science: grammar.” (Spade)
  • Real science has personal supposition; rational science has simple supposition; grammatical science has material supposition.

The following OntoUML diagram presents Ockhams’s model of the relation between supposition and sciences:

William Ockham on Supposition and Sciences
Propositionproposition or sentence is made up of terms.component of Science
TermA mental, spoken, or written term.component of Proposition; supposits for Suppositum
SuppositumSuppositum is “whatever a term supposits for’ or refers to.”role of Term
Supposition“What sort of relation is supposition? Well, the first thing we can say about it is that supposition is a semantic relation. To a first (but pretty good) approximation, supposition in this first part of the theory is what nowadays we call ‘reference.’ It is the relation between the terms used in a proposition and the things those terms are used to talk about in that proposition. […]
supposition occurs only in a propositional context. And this is the first main difference between supposition and signification, which can occur outside a propositional context according to almost any author.
The second main difference is this: We do not always in practice use terms in propositions to talk about what those terms signify. We use them in a variety of other ways too. Hence supposition also differs from signification insofar as a term may signify one thing, but supposit on a given occasion for something entirely different.” (Spade – History of the Problem of Universals in the Middle Ages)
relates Proposition; Supposition; Suppositum
PersonalSupposition“Going with the ‘real’ sciences, there is what is called ‘personal’ supposition (which has nothing especially to do with persons — although it perhaps originated in theorizing about the persons of the Trinity). There terms stand for the things they signify. For example, in the sentence ‘Man is an animal’, the subject term ‘man’ is in personal supposition, and stands for individual human beings. They are the ones who are animals. The spoken or written word is not an
animal, and neither is the concept.” (Spade)
subkind of Supposition
SimpleSupposition“Going with the ‘rational’ science of logic, there is what is called “simple” supposition. There terms stand for concepts they do not signify. These concepts are the genera and species that logic talks about. For instance, in the sentence ‘Man is a species’ (in the sense in which it is true), the subject term ‘man’ stands for the concept “man,” which is a species — that is, a species-concept. It definitely does not
stand for any real universal man.” (Spade)
subkind of Supposition
MaterialSupposition“Going with ‘grammatical’ science, there is what is called ‘material’ supposition, in which terms stand for words they do not signify. For example, in ‘Man has three letters’, the subject term ‘man’ is in material supposition — at least in the sense in which the sentence is true. (But don’t make the mistake of thinking that Ockham’s “material supposition” is just what we do with quotation marks. It is more
complex than that.)” (Spade)
subkind of Supposition
ScienceFor Ockham, the object of a science is simply sentences with general terms in them. That’s how he accommodates Aristotle’s dictum that science deals with the universal.
This of course doesn’t mean that we can never, in our knowledge, get beyond the level of language to things. For Ockham, there are two senses of the term ‘know’ (= scire in Latin, from which comes scientia = science”):
(a) As we just said, the sense in which to know is to know a sentence, or a term in that sentence. In this sense, the object of a science is universal.
(b) We can also be said to know what that sentence is about, what the subject-term in it stands or supposits for. What we know in this sense is invariably the individual, metaphysically speaking, since there is nothing else for Ockham. This is not the object of science in the sense Aristotle is talking about. […]
Traditionally, there were three kinds of sciences people distinguished: (a) the so called ‘real’ sciences: physics, metaphysics and mathematics; (b) the so called ‘rational’ science: logic; and (c) ‘grammatical’ science: grammar. For each of these kinds of science, Ockham distinguishes a kind of ‘supposition.’” (Spade)
RealScience; “Traditionally, there were three kinds of sciences people distinguished: (a) the so called ‘real’ sciences: physics, metaphysics and mathematics” (Spade)subkind of Science; has PersonalSupposition
RationalScience; “Traditionally, there were three kinds of sciences people distinguished: (b) the so called ‘rational’ science: logic” (Spade)subkind of Science; has SimpleSupposition
GrammaticalScience“Traditionally, there were three kinds of sciences people distinguished: (c) ‘grammatical’ science: grammar. For each of these kinds of science, Ockham distinguishes a kind of ‘supposition.’” (Spade)subkind of Science; has MaterialSupposition


First published: 9/12/2021

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