• TheMadFool
    13.8k


    I've got an issue with presuppositions with regard to free logic and the supposed circularity (question begging) in Descartes' argument and others like it.

    You claim that I think, therefore I am is circular because I think, according to you, presupposes that I am.

    I've always been a little confused by conditionals. Take the following two statements:

    1. If it rains then the ground will become wet [classic entailment: rain makes the ground wet]

    2. If you're relying on arguments to make a point then you endorse the utility of logic in making a point [presupposition: arguments presuppose logic]

    Come now to Descartes' argument:

    3. I think

    Ergo,

    4. I am

    Is this conditional (I think I am) an entailment or a presupposition? Both? Neither?
  • Banno
    25k
    Is this conditional (I think → I am) an entailment or a presupposition? Both? Neither?TheMadFool


    An entailment.
  • TheMadFool
    13.8k
    Put anther way, in trying to show the validity of "I think therefore I exist" it instead shows that it is circular, that "I think" already supposes that "I exist".

    Descartes' argument is valid, but circular.
    Banno

    An entailment.Banno

    Didn't you say that it was a presupposition?

    Perhaps it's both but then that doesn't help, does it?
  • Banno
    25k
    "I think" is the assumption; "I think" presupposes the thinker.
  • TheMadFool
    13.8k
    "I think" is the assumption; "I think" presupposes the thinker.Banno

    To think, there's got to be a thinker. That's why Descartes' argument works. This is, as you said, an entailment.

    I would treat the thinker as a necessary condition to be able to say "I think". Are all necessary conditions presuppositions.

    My hunch is: all presuppositions are necessary conditions but not all necessary conditions are presuppositions.
  • frank
    15.8k
    think" is the assumption; "I think" presupposes the thinker.Banno

    Which isn't a problem for Descartes' purposes.
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