Earlier quoted context omitted.
I don't think say Kierkegaard or Nietzsche can be reduced to just making definitions.
Why? Could you please elaborate(
>"When I analyze the process that is expressed in this sentence, 'I think,' I find a whole series of daring assertions that would be difficult, perhaps impossible, to prove—for example, that it is I who think, that there must necessarily be something that thinks, that thinking is an activity and operation on the part of a being who is thought of as a cause, that there is an 'ego,' and, finally, that it is already determined what is to be designated by thinking—that I know what thinking is.
Good luck convincing a skeptic like that to take your definitions for granted, or believe in any conclusions you draw from your definitions.