"convinced without" is a grammatically correct phrase that can be used in written English.
It is often used to describe a situation where someone is convinced or persuaded to do something without the help or influence of others. Example: Despite the lack of support from his colleagues, John was convinced without any outside assistance that his proposal would be successful. In this sentence, "convinced without" indicates that John was able to come to a decision on his own, without any external persuasion or influence.
"He had me convinced without him, I had nobody," Mr. Rabiega said.
Campbell said he was convinced, "without any names or proof, that there is an attempt to move the headquarters to New York".
"I feel a little more confident than I was when I first thought of Hoecker's being the officer on the ramp," Erbelding told me, "but I don't think I'll ever be convinced without a forward-facing photograph".
Senior European and American diplomats and officials are also convinced, without supplying hard evidence, that the Russians have infiltrated, or are helping to fund, NGOs campaigning in Europe against fracking and the proposed free trade agreement between the EU and the US, and that they have also been quietly encouraging the Scottish and Catalan secessionist movements in Britain and Spain.
Yesterday his long-time collaborator, the eminent epidemiologist Sir Richard Peto, said such allegations were a deliberate attempt to tarnish the reputation of "far and away the best cancer epidemiologist in the world for a long time" by those who are convinced without sufficient evidence that environmental pollutants, such as toxic chemicals, are a major cause of cancer.
They were convinced, without really having any proof, that there were irregularities in the vote.
Someone who knows Stewart well described his defining talent as the ability to sound convincing without expertise.
Refreshingly, the statement it makes about young artists' preoccupations is convincing without being portentous, ironic, or abject.
Under the restrained direction of Ruben Santhego-Hudson, the actors are convincing without managing to create fully compelling portraits from these two-dimensional figures.
What fascinated me was how the actors got inside their roles and managed to be convincing without you feeling any effort.
Still others thought that they were not even necessary and an essay could be convincing without having quotations.
