Full Idea
It has been argued that the tensed view of time is actually committed to the unreality, not just of the future, but of the past also.
Gist of Idea
It is claimed that the tense view entails the unreality of both future and past
Source
Robin Le Poidevin (Intro to 'Questions of Time and Tense' [1998], Intro)
Book Reference
'Questions of Time and Tense', ed/tr. Le Poidevin,R [OUP 2002], p.2
A Reaction
There seem to be strong and weak version here, since if you are committed to tenses, you are presumably committed to the possibility of truths about the past and future. The strong version (denying past and future) seems to make tenses pointless.