Can you confirm the following expression is used in common and formal cases?
"What is certain is that..."
As a native German, studying academic English, it sounds slightly strange. May I ask for your confirmation? Is a comma needed?
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What is certain is that . . ..
As a concluding thought in a line of reasoning, which is characterized by the existence of an uncertainty (or, uncertainties), the above phrase would be appropriate and not as stilted if its second word (viz., is) is emphasized by being italicized.
What is certain is that . . .."
So for example, if the line of reasoning goes as follows,
While we are uncertain about what course to take, what is certain is that we need to make a decision now, before we run out of time,
then the phrase makes perfect sense. It also provides balance to the line of reasoning and is a good substitute for the locution
On the one hand . . ., but on the other hand . . ..
This is not an uncommon construction in academic English. For example:
- What is certain is that more research is needed to improve modeling of the climate in the Great Lakes region.
- What is certain is that a monetary value can only be applied to natural capital if it is considered on a smaller scale.
- What is certain is that prolonged exposure to unwanted noise at any level can be a source of great stress.
Such constructions are called pseudo-clefts, where the what clause functions as the subject followed by the simple predicate (the copula is). Subjects should not be separated from their predicates by a comma.