Frege [Rigo Acevedo]

I like Frege's argument for explaining how the relationship of "a=b" and "a=a" can both exist and have different cognitive values. His discussion of subordinate clauses, and their ability to express equivalent truth clauses for a common referent that they represent- while not possessing a common structure- does give support to his argument that two sentences (a and b) can discuss different senses, but still contain a significant similarity in their structure that their truth clauses are not inherently different from one another.

Frege discusses the grammatical forms of subordinate clauses when discussing instants of time, (pg 19). I would be interested in knowing how Frege would consider sentences that discuss a common referent, but in different tenses. The statements, "The leaves that are green" and "The leaves that used to be green", appear to express a common referent; and since I am discussing a referent at a different period in time my description of the object may change, but does that necessarily mean each sentences holds a different sense? I could have the same discussion with a person at one period of time in the year, and then have the same conversation again, but my description of the referent may need to change, and in this case I would argue that the sense has not changed, but I feel that Frege might, given his description of sense (pg 4).