So Protagoras (485 415 BCE), who included wish, question, answer and command (Diels Kranz (DK) 80.A1, Diogenes Laertius (D. L). 9.53 4), and Alcidamas (pupil of Gorgias, fl. 4th BCE), who distinguished assertion (phasis), denial (apophasis), question and address (prosagoreusis) (D. L. 9.54).
Still, it is not easy to distinguish assertion from presupposition in pure speech act terms.
This undertaking, according to Kölbel, also distinguishes assertion from presupposition, although in a more subtle way.
Pointing to the difference between fact-stating and evaluative discourse may help to distinguish assertions from evaluations, but does not, again, help to distinguish assertion from other acts within the fact-stating family, such as conjectures and assumptions.
In fact, unless we read a lot into "stating", it is not enough even to distinguish assertion from other acts that concern facts, or states of affairs, such expressing a wish that a fact obtains.
This also distinguishes assertions from promises and commands, where the proposition is not presented as subject to the hearer's safeguards; "rejection is not presented as an option for the hearer" (2010: 73).
It defines the demarcation criterion of science from pseudoscience, distinguishing assertions that can garner consensus from matters of taste and prejudice.
This idea of commitment can also serve to distinguish between assertion proper and weaker constative forms, such as guesses and conjectures, since these differ from assertion with respect to commitment.
This is a principal feature: a modular model may treat distinct formulas \(F\) and \(G\) as equal in the sense that \(F^\ast = G^\ast\), but still be able to distinguish justification assertions \ tF\) and \ tG\), for example when \(F \in t^\ast\) but \(G\not\in t^\ast\) yielding \({\Vdash}tF\) but \(\not\Vdash tG\).
Going further \({\textsf{LP}}\), and Justification Logic in general, is not only sufficiently refined to distinguish justification assertions for logically equivalent sentences, it provides a flexible machinery to connect justifications of equivalent sentences and hence to maintain constructive closure properties necessary for a quality logic system.
A line of defense against examples of this type, adopted by Grice (1991) and by Lewis (1973), is to distinguish carefully between assertion conditions and truth conditions.
