  How does this detour through speaker meaning help to elucidate the notion of force? One way of asserting that P, it seems, is overtly to manifest my commitment to P, and indeed commitment of a particular kind: commitment to defend P in response to challenges of the form, “How do you know that?” I must also overtly manifest my liability to be either right or wrong on the issue of P depending on whether P is the case. By contrast, I conjecture P by overtly manifesting my commitment to P in this same “liability to error” way, but I am not committed to responding to challenges demanding full justification. I must, however, give some reason for believing P; this much cannot, however, be said of a guess.