A very natural objection to the way in which I have introduced e.g. propositions of the form xRy is that by it propositions such as (∃x,y).xRy & similar ones are not explained, which yet obviously have in common with aRb what cRd has in common with aRb. But when we introduced propositions of the form xRy we mentioned no one particular proposition of this form; & we only need to introduce (∃x,y).ϕ(x,y) for all ϕ's in any way which makes the sense of these propositions dependent on the sense of all propositions of the form ϕ(a,b), & thereby the justification of our procedure is proved.