I'm wondering about 'to-Infinitive' and subordinate conjunction 'that'.
Is there any difference in meaning between following sentences?
- I believe him to be honest.
- I believe that he is honest.
In this case there is no substantive difference. The version with the infinitive is stiffer and more formal.
Note, however, that with believe this equivalence only holds when the complement expresses a current state, with either a stative lexical verb (for example, be in your example) or a perfect or progressive construction.
okI believe (that) he is coming tomorrow.
okI believe him to be coming tomorrow.
okI believe that he has come.
okI believe him to have come.
You cannot use the infinitive version with a verb expressing a past or future event:
okI believe that he came yesterday, but not
∗ I believe him to come yesterday.
okI believe that he will come tomorrow, but not
∗ I believe him to come tomorrow.
OK so lets call the first sentence (1) and the other one (2).
So, the contrast between sentence (1) and (2) is that in (1) there is to infinitive. However, both (1) and (2) present epistemic commitment to what it is said.
Also, "I believe that he is honest" could be represented with "I know that he is honest".
Last but not least, my dictionary says:
I believed (that) he was honest. = I believed him (to be) honest.
I hope that I have helped you in some way. :)