ascribable in a sentence

Is his failure ascribable to incompetence or to bad luck?

1- The critic was the author of several works outside his field of expertise and themselves ascribable to literature.

2- Stern notes that the defeat of Foraker “was ascribable largely to the efforts of Hanna”.

3- Who could say whether his silence were ascribable to the absence of danger, or to his own absence?

4- The author’s identity is only given as “T. H.,” but the work is ascribable to Thomas Heywood.