The phrase "acknowledged himself as" is correct and usable in written English.
It can be used when someone is recognizing or admitting their identity or role in a particular context.
Example: "After much reflection, he acknowledged himself as the leader of the group."
Alternatives: "recognized himself as" or "identified himself as".
And whereas Mr Luzhkov still refuses to acknowledge himself as a presidential candidate, he ranks among the top two or three by anybody else's reckoning.
And he began to win: he was able in 2014 to acknowledge himself as the recipient of the NSL, and in December of that year exercised an annual option to challenge residual secrecy.
"As Stier acknowledges himself, no labor union in the history of the United States has conducted as extensive an internal program to free itself of any remaining influence of organized crime as the I.B.T. has under this administration".
But as he acknowledges himself, we did invent something very much like UTCs under the 1944 Education Act, which offered not just grammar schools and secondary moderns, but selective technical schools.
Taylor himself acknowledged that, as his Guardian career progressed, he 'may have had a reputation for being a bit frivolous with jobs and getting rid of people quickly... but it was jolly hard to find people who were good enough to stick!' Universal popularity proved unnecessary though, and Taylor went on to become managing director when Gibbings took over Laurence Scott's role as chair in 1973.
The distinction goes back at least to Kant, and it (or something like it) had appeared in the works of T. H. Green, Bernard Bosanquet, and Boris Chicherin, and had more recently been used by Guido de Ruggiero, R. G. Collingwood, John Petrov Plamenatz, and Dorothy Fosdyke, among others; Berlin himself acknowledged Benjamin Constant as the main influence on his thinking.
Domenech acknowledged as much.
Ephron has acknowledged as much.
