'Suppose a person to buy a horse' - Grammaticality in 1871

Question

[Para 2, CJ Cockburn's judgment:] All that can be said is, that the two minds were not ad idem as to the age of the oats; they certainly were ad idem as to the sale and purchase of them. Suppose a person to buy a horse without a warranty, believing him to be sound, and the horse turns out unsound, could it be contended that it would be open to him to say that, as he had intended to buy a sound horse, and the seller to sell an unsound one, the contract was void, because the seller must have known from the price the buyer was willing to give, or from his general habits as a buyer of horses, that he thought the horse was sound? The cases are exactly parallel.

I would've written 'Suppose THAT a person to buy[S] a horse without a warranty'. Is Cockburn's grammar right? If so, what are some formal terms describing this issue or his syntax that I've never seen before?

Answer 1

This is the same infinitival complement you find with, for instance, want and expect:

I want him to buy a horse.
I expect him to buy a horse.
I suppose him to buy a horse.

Infinitival complementation with such verbs as suppose, imagine, think, conceive is not so common as it once was, but it is still to be encountered, particularly in academic contexts. Here are some recent examples:

I don’t understand what Eliot means by intensifying the world “to his emotions.” I suppose him to mean that artists work up their sense of the world to the pitch of intensity at which it seems to justify their emotions, however violent. —Denis Donghue, Words Alone, 2002.

Programmers are a different breed, but they're not the stereotypical mutant pocket protector geeks that project managers may imagine them to be. —Teresa Lackey and Joseph Phillips, Software Project Management for Dummies, 2011.

Bernstein's ideas have been criticized, often by those who mistakenly thought him to have been claiming that middle-class speech patterns are somehow superior to those of the working class. —Lawson and Garrod, Dictionary of Sociology, 2001.

Answer 2

Sure, I would have written it that way, too – if I wrote it yesterday. But who knows how I would have written it 150 years ago?

What are some formal terms describing this issue or his syntax that I've never seen before?

Try antiquated or obsolete; you could even call it 19th-century English.

Informally, you might try calling it old English, although many linguists would tell you that the passage is much too modern for that label. If you want to know more, try reading here.

Answer 3

You could call it Victorian English as well (referring to the time period of Queen Victoria's reign in England, namely 1837 - 1901); this is commonly done for architectural styles of the time.