(using the ordinal number ‘5’), through the processes of abstraction and reification, which ultimately leads (via the cardinal number ‘5’) to the abstract concept of ‘number’.
This account is not offered as a psychological hypothesis, but as a theoretical reconstruction of the genesis of subjective mathematical knowledge by abstraction.
What is proposed is that by a vertical process of abstraction or concept lorrnation, a collection of objects or constructions at lower, pre-existing levels of a personal concept hierarchy become ‘reified’ into an object-like concept, or noun-like term.
Skemp refers to this ‘detachability’, or ‘the ability to isolate concepts from any of the examples which give rise to them’ (skemp, 1971, page 28) as an essential part of the process of abstraction in concept formation.
Such a newly defined concept applies to those lower level concepts whose properties it abstracts, but it has a generality that goes beyond them.
The term ‘reification’ is applied because such a newly formed concept acquired an integrity and the properties of a primitive mathematical object, which means that it can be treated as a unity, and at a subsequent stage it too can be abstracted from, in an iteration of the process.
The increasing complexity of subjective mathematical knowledge can also be attributed to horizontal processes of concept and property elaboration and clarification.
This horizontal process of object formation in mathematics is that described by Lakatos (1976), in his reconstruction of the evolution of the Euler formula and its justification.
Namely, the reforrnulation (and ‘stretching’) of mathematical concepts or definitions to achieve consistency and coherence in their relationships within a broader context.
This is essentially a process of elaboration and refinement, unlike the vertical process which lies behind ‘objectification’ or ‘reification’.
Thus far, the account given has dwelt on the genesis and structure of the conceptual and terminological part of subjective mathematics.
There is also the genesis of the propositions, relationships and conjectures of subjective mathematical knowledge to be considered.
But this can be accommodated analogously.
We have already discussed how the elementary truths of mathematics and logic are acquired during the learning of mathematical language.
As new concepts are developed by individuals, following the hierarchical pattern described above, their definitions, properties and relationships underpin new mathematical propositions, which must be acquired with them, to permit their uses.
New items of propositional knowledge are developed by the two modes of genesis described above, namely by informal inductive and deductive processes.
Intuition being the name given to the facility of perceiving (i.e., conjecturing with belief) such propositions and relationships between mathematical concepts on the basis of their meaning and properties, prior to the production of warrants for justifying them.
Overall, we see.
Therefore.
That the general features of the account of the genesi of mathematical concepts also holds for propositional mathematical knowledge.
That is we posit analogous inductive and deductive processes, albeit informal, to account for this genesis.
In summary, this section has dealt with the genesis of the concepts and propositions of subjective mathematical knowledge.
The account given of this genesis involves four claims.
First of all, the concepts and propositions of mathematics originate and are rooted in those of natural language, and are acquired (constructed)