On the Fregean view of quantifiers, quantifiers express properties of properties. Thus, ∀ expresses a property U of Universality and ∃ expresses a property I of instantiatedness. So, ∀xFx says that Fness has universality, while ∃xFx says that Fness has instantiatedness.
One of Hintikka's criticisms is that it is hard to make sense of nested quantifiers. Consider for instance
- ∀x∃yF(x,y).
But the Fregean can say this about ∀x∃yFxy. For any fixed value of x, there is a unary predicate λyFxy such that (λyFxy)(y) just in case Fxy. The λ functor takes a variable and any expression possibly containing that variable and returns a predicate. Thus, λy(y=2y) is the predicate that says of something that it is equal to twice itself.
Now, for any predicate Q, there is a property of Qness. So, for any x, there is a property of (λyFxy)ness. In other words, there is a function f from objects to properties, such that f(x) is a property that is had by y just in case F(x,y). We can write f(x)=(λyFxy)ness.
Now, we can replace the inner quantification by its Fregean rendering:
- (λyFxy)ness has I.
- [λx[(λyFxy)ness has I]]ness has U.
We can now ask which proposition formation rules were used in the above construction. These seem to be it:
- If R is an n-ary relation and 1≤k≤n, then for any x there is an (n−1)-ary relation Rk,x which we might call the <k,x>-contraction of R such that x1,...,xk−1,x,xk+1,...,xn stand in R if and only if X1,...,xk−1,xk+1,...,xn stand in Rk,x.
- If p is a function from objects to propositions, then there is a property p* which we might call the propertification of p such that x has p* iff p(x) is true.
- There are the properties I and U of instantiation and universality, respectively.
Observe that if P is a property, i.e., a unary relation, then the contraction P1,x is a proposition (propositions are 0-ary relations), equivalent to the proposition that says of x that it has P.
With these two rules and the relation R that is expressed by the predicate F, start by defining the function f(x) that maps an object x to the property R1,x, and then define the function g(x) that maps an object x to the proposition I1,f(x). Thus, g(x) says that x stands in R to something. Now, we can form the propertification g* of the function g, and to get (1) we just say that g* has U. Thus the proposition that is expressed by (1) will be U1,g*.
One worry about proposition formation rules is that we might fear that if we allow too many, we will be able to form a liar-type sentence. A somewhat arbitrary restriction in the above is that we only get to form a propertification for functions of first-order objects.
Another worry I have is that I made use of the concept of a function, and I'd like to do without that.
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