What is the difference between "although that is" and "although it is"?

Currently I'm writing a thesis. I came over the although sentence several times. After reading through time after time my head started to hurt :P I tried to google it but didn't find any help.

So the sentence goes like this:

Although that/it is true, it is not insensible since one rule alone cannot classify the entire data.

What comes before Although is a sentence trying to explain the bad results from a program shown in a table.

What is the difference? Is it possible to use both? If so, why?

Also the part with "it is not insensible since" sounds fishy to me. Is this one correct?

Solution 1:

It is impossible to be sure without more context, but either that or it is likely to be acceptable: both are syntactically pronouns here and refer to a previously stated proposition.

Insensible is almost certainly wrong. The word may mean

• "incapable of sensory perception, unconscious" or

• "incapable of being sensed or perceived by the senses"

and it is difficult to conceive an entity which might be described as both true/false and sensible/insensible. Your author may mean something like detectable or discernible.

Alternatively: Since sensible has as one of its meanings "characterized by good sense, reasonable", it is also possible that your author, working from a bilingual dictionary, may have employed insensible as the equivalent of a word in their own language with a range of meanings including both "unreasonable" and "irrelevant" or "inconclusive"—either of those words would fit the context.