Their results or conclusions
X’s explanation depends on or relies on …
The evidence for … is inconclusive
The reasoning here is problematic
the conclusions are somewhat weak
X’s arguments … are unconvincing
this, however, holds only for …
the claim or argument that … simply does not hold water
… is not sufficient argument for the existence of etc. …
this assumption is rather arbitrary, however
X’s main assumption that … is debatable or problematic
We would dispute X’s conclusion that …
X’s explanation for or of … is rather or highly speculative
this contradiction has also been pointed out by X
an error in the calculation
X’s figures, results, conclusions etc. should, however, be treated with caution
The results should be treated with a degree of or some or considerable caution
X’s conclusions would carry more weight if …
further clarification of … is required
X and Y fail to explain …
the causal relationship between … and … needs to be clarified
a number of valid criticisms
… violates the principle of …
This invalidates, however, …
X’s argument rests or depends almost entirely on …
X’s statement or theory etc. … requires some qualification
X gives a detailed if not always tenable analysis of …
X attempts, unsuccessfully in my or our view, to …
Where X’s argument or explanation falls down is in …
X’s explanation is not implausible, if not entirely satisfactory
Further research is necessary to establish a clearer relationship between … and …
Further research is necessary before ascribing … to …
A more complete explanation of … would …
a simplistic assumption