I'm writing an essay on a (very old) functional exposition of judgement. I note that two functions of the mind respectively provide what is functionally equivalent to the statements
'If a particular, P, bears the mark, M, then P is an instance of the universal, U'.
'P bears the mark M'.
which collectively constitute the input of another function, which outputs the propositional judgement
'P is an instance of U'
Put simply: the first two propositions are only analogous to representations which do not need to be, and likely aren't, explicit (i.e. they're not something we're necessarily cognizant of having). However, the third one isn't meant to be analogous. It's exactly the sort of thing we could hear ourselves thinking (e.g. 'That thing is a tree').
Are there delimiters (parentheses, fonts, etc.) that convey that what they delimit is a proposition? Alternatively, are there delimiters that convey that what they delimit is functional, or analogous to something else, or otherwise able to convey the difference between the first two statements and the third statement?
The easiest thing to do would just be to state the difference. However, my professor's a big of using notation wherever there's a convention for it (even a weak convention). I'm also asking for the sake of my own curiosity.
(I acknowledge that this question straddles cognitive science and linguistics, but given the close relationship of the two disciplines to each other, and that the question is about the notation related to a linguistic object (a proposition), it seemed appropriate to ask it here.)