We can believe, without the shadow of a doubt, that the I in question formed itself, if it manages to do at least that , and if the disorder of identity of identity of which we were speaking a while ago does not, precisely, affect the very construction of the I, the formation of the speaking-I [dire-je], the me-I [moi-je], or the appearance, as such, of a pre-egological ipseity. (29)

That is all it knows how to do, to keep people waiting, and that is all I know about it. Even today and, without the shadow of a doubt, for good. (71)

why always the shadow of the doubt?

Derrida seems to be afraid, to tremble in this phrase -- maybe it's the accent he doesn't want us to read?

it recalls the shadow of the valley of death

Generally, I have heard this phrase used to assert truth, but Derrida uses it in relation to belief. I do not know of a belief which has no shadow of doubt.

The very figure of belief implies non-belief, disbelief.

Since I always tell the truth, you can believe me. (50)

Thus Derrida is always lying just a little bit with us.

Somehow is lying seems so delicately honest that it make me catch my breath to think of it.

 The improvisation of some inaugurality is, without the shadow of a doubt, the impossible itself . . . At the same time, this untranslatable translation, this idiom makes things happen [fait arriver], this signature brought forth [fait arrivée], produces events in the given language, the given language to which things must still be given, sometimes unverifiable events; illegible events. Events that are always promised rather than given. Messianic events. Bust the promise is not nothing; it is not a non-event. (66)