is impossible, for example, to introduce as primitive ideas both the
concept of a function and specific functions, as Russell does; or the
concept of a number and particular numbers.


4.1273 If we want to express in conceptual notation the general
proposition, 'b is a successor of a', then we require an expression for the
general term of the series of forms 'aRb', '(d : c) : aRx . xRb', '(d x,y)
: aRx . xRy . yRb', ... , In order to express the general term of a series
of forms, we must use a variable, because the concept 'term of that series
of forms' is a formal concept. (This is what Frege and Russell overlooked:
consequently the way in which they want to express general propositions
like the one above is incorrect; it contains a vicious circle.) We can
determine the general term of a series of forms by giving its first term
and the general form of the operation that produces the next term out of
the proposition that precedes it.


4.1274 To ask whether a formal concept exists is nonsensical. For no
proposition can be the answer to such a question. (So, for example, the
question, 'Are there unanalysable subject-predicate propositions?' cannot
be asked.)


4.128 Logical forms are without number. Hence there are no preeminent
numbers in logic, and hence there is no possibility of philosophical monism
or dualism, etc.


4.2 The sense of a proposition is its agreement and disagreement with