The phrase "a sort of proof" is correct and usable in written English.
It can be used when describing something that provides evidence or support for a claim, but is not definitive or conclusive.
Example: "The data collected from the experiment serves as a sort of proof that our hypothesis was correct."
Alternatives: "a kind of evidence" or "a type of validation".
Not only is the payout less, but the insurance often requires a multiday hospital stay as a sort of proof that the depression or anxiety is real.
For us, this is a sort of proof not only that our new wave is important, but that we have succeeded in setting up an event significant enough that Lincoln Center wants our public to go there".
Liberals have long viewed health reform as the opening wedge, a sort of proof of concept, in a campaign to strengthen the US safety net and reduce income inequality; that was basically what I was urging in Conscience of a Liberal, which gave its title to this blog.
Medina Mora and others insisted that Mexico's institutions of criminal justice had improved dramatically since Guzmán's earlier escape, and that the prosecution of someone who had once seemed so untouchable would represent an important benchmark for rule of law in the country — a sort of proof of concept.
The Surface line started off pretty humbly – a sort of proof of concept for Windows 10.
The headset ships with a cube that offers a neat augmented reality experience (which utilizes the phone's unobstructed camera, serving as a sort of proof of concept for app developers).
They're leading the whole project with a sort of proof-of-concept disc comprising the pilot episode and two fan favorites, "Sins of the Father" and "The Inner Light," from seasons three and five respectively.
So FSMA was designed to have the flexibility to adapt to changes in the market — a sort-of future-proofing.
A large leap was made in assigning any sort of "proof" from the small Lancet study.
"Have you any sort of proof?" Rummins laid his head to one side and gave me a long sly broken-toothed grin.
Celebrities are often wheeled out to add appeal to games launches, often without providing any sort of proof that they actually are gamers.
