grammar - What’s the difference between [v] たとしても and just the plain ても

What’s the difference between [v] たとしても and just the plain ても? Example:

(1) 説明書を読んでも分かりにくい

(2) 説明書を読んだとしても分かりにくい

Answer

The difference between these two hinges on whether or not the action has been completed at the time the statement was made:

説明書を読んでも分かりにくい

This could be taken in one of two ways:

1. 
   

   Even if you (I) read the instructions, it will [still] be hard to understand.

   
   


2. 
   
   

   Even after reading the instructions, it is [still] hard to understand.

   
   

So with the ～ても form in this sentence, the action (読む) may have already taken place, or it may be a hypothetical action to take place in the future.

説明書を読んだとしても分かりにくい

By contrast, the ～としても pattern always refers to a hypothetical situation which may or may not take place in the future. As such, the translation "even supposing you were to [action]" often works well for ～たとしても:

1. Even supposing you (I) were to read the instructions, it would [still] be hard to understand.

Note that while both ～ても and ～たとしても can both express hypothetical cases, ～ても better matches a "even if … will" pattern, while ～たとしても better matches a "even supposing … would" pattern in English.