All the textbooks I have ever come across during the course of my studying English emphasize that future tense should not be used in conditional clauses.
If it rains in the evening, we will not go for a walk. (
if it will rain in the evening...)
We decided to go for a walk if it didn't rain in the evening. (
...if it wouldn't rain in the evening)
However, in the following sentence I'm really inclined to use the future tense.
Don't implement this feature if it will significantly increase the complexity of the user interface.
According to all the rules I know of, the future tense is illegal here. However, my gut feeling tells me that the sentence is correct. If I am wrong, the question ends here. Otherwise please read on. I find the last example different from my first two because:
- In the first examples we must wait and see if the condition is true, and then make a decision accordingly, whereas in the last example, we must actually analyze/predict/forecast the future in order to make the decision in the present.
- (might be irrelevant) In my first language - Armenian - where we have a special mood for conditions, the translation of the third sentence actually uses indicative, whereas the first two use that special mood (the conditional mood, as it were).
Since the second would-be principle is easier for me to experiment with, I noticed that every time a condition uses the indicative mood in my language, I'm inclined to use the future tense in English. As another example:
I will give you the money if it will make you happier.
Am I imagining things or are my examples of the future tense in the conditional clause valid? If they are valid, what rule would you suggest to distinguish the cases when it's OK? (I do realize that translating a sentence to another language and analyzing the translation doesn't really count as a rule).