Phrase for saying we can only speculate
You can write it in a passive voice:
"This can only be speculated at this point."
You can check the usage in more formal texts here site:gov "can only be speculated"
or
This is only speculation at this point.
This is a matter of speculation at this point.
site:gov "a matter of speculation at this point"
As in:
"We can only presume at this point."
presume TFD
- To take for granted as being true in the absence of proof to the contrary: