Final answer:
Churchill uses ethos in his statement to appeal to the audience's sense of duty and also to establish credibility for the reasons behind continuing the war.
Step-by-step explanation:
In the statement, “I have thought it right upon this occasion to give the house and the country some indication of the solid, practical grounds upon which we base our inflexible resolve to continue the war”, Churchill primarily employs ethos as the rhetorical device. Ethos pertains to the credibility of the speaker and his moral character. Churchill appeals to the audience's sense of duty and moral obligation to continue the conflict, suggesting it is founded upon “practical grounds”. This appeal aims to engender trust and demonstrate the solid rationale behind the decision to persist in the war, aligning the listener with a sense of patriotism and shared values.
Churchill most clearly uses ethos in the given statement. Ethos is an appeal to the credibility and authority of the speaker. In this case, Churchill establishes his credibility by referring to the solid, practical grounds upon which their resolve to continue the war is based. By doing so, he appeals to the audience's trust in his judgment and expertise.