Impute motives to somebody

To impute a motive to someone is to assume or conclude that the person had that motive. The term is generally used when the person assigning the motive has no evidence, or only limited evidence, that the motive is accurate. The term "impute" is often used with a somewhat negative connotation, implying that a person has assumed a motive unjustifiably, where other possibilities exist. The term "impute" is particularly likely to be used when the motive under discussion is itself negative. For example

You should not impute greed to him, he may have acted out of misplaced caution.

The word "impute" can also be used where the motive being assigned or assumed is neutral or positive, but is not as common in that context.