Nous comparons, non pas que cela change, mais pour décider.

Non pas que is a set expression meaning something like not that... or not because....

In this sentence, it introduces a reason that the speaker wants to reject:

• Nous comparons = we compare
• non pas que cela change = not that it changes anything
• mais pour décider = but in order to decide

So the structure is:

• not because X
• but in order to Y

This is a fairly elegant or formal way to contrast a false reason with the real one.

Here, que introduces a whole clause:

• que cela change

French often uses que to introduce subordinate clauses where English might use that, because, or no word at all depending on the structure.

In non pas que..., the que is part of the fixed pattern. You should learn non pas que as one unit, rather than trying to interpret non pas and que separately every time.

It is understood as subjunctive.

The expression non pas que normally triggers the subjunctive, because it presents something as denied, hypothetical, or not being asserted as a real cause.

With changer, the 3rd person singular present indicative and present subjunctive are both spelled change, so the form looks the same:

• Indicative: cela change
• Subjunctive: que cela change

So in this sentence, even though the spelling does not change, the grammar is subjunctive because of non pas que.

A verb with a visibly different subjunctive form makes this easier to see:

• Non pas qu’il est fatigué ❌
• Non pas qu’il soit fatigué ✅

Because non pas que does not present the clause as a straightforward fact. It rejects that clause as the real explanation.

French often uses the subjunctive after expressions involving:

• doubt
• denial
• emotion
• subjectivity
• purpose or non-factual explanation

Here, the speaker is saying: it is not the case that we compare because that changes anything. Since that reason is being dismissed rather than stated as fact, the subjunctive is used.

Pour décider expresses purpose: in order to decide.

So the sentence contrasts:

• a reason that is not true: non pas que cela change
• the real purpose: mais pour décider

French often uses pour + infinitive where English uses:

• to decide
• in order to decide
• so as to decide

This is very common and natural in French.

Because the sentence is explaining why the action is done, not stating a second separate action.

• pour décider = to decide / in order to decide
  → gives the purpose of comparing

If you said mais nous décidons, that would mean but we decide, which sounds like a separate statement, not the purpose of comparing.

So:

• Nous comparons... pour décider = We compare... in order to decide

That is the more natural structure for expressing purpose.

Both cela and ça can mean that or it, but they differ in register.

• cela = a bit more formal, neutral, written
• ça = more informal, conversational

So:

• non pas que cela change sounds more polished
• non pas que ça change would sound more spoken and casual

Because non pas que itself is already somewhat formal, cela fits the style better.

In French, subject pronouns are normally required.

So even though comparons clearly means we compare, you still need:

• Nous comparons

Unlike in Spanish or Italian, French usually does not drop the subject pronoun in normal sentences.

So Comparons by itself would usually sound like an imperative:

• Comparons ! = Let’s compare!

That is why nous must be there.

The commas separate the parenthetical contrast:

• Nous comparons, non pas que cela change, mais pour décider.

They help show that non pas que cela change, mais pour décider is an inserted explanation of motive.

In English, you might also pause around a phrase like:

• We compare, not because it changes anything, but to decide.

So the commas mainly guide rhythm and clarity.

It is understandable and grammatical, but it sounds fairly formal or literary, especially because of non pas que.

In more everyday spoken French, people might say things more simply, for example with a structure equivalent to:

• We compare not because it changes anything, but to make a decision
• We compare, not that it changes anything, but to decide

So the sentence is fine, but it is not especially casual conversation style.

You can get close, but a fully word-for-word translation may sound odd in English.

French:

• non pas que cela change

Possible English renderings:

• not that it changes anything
• not because that changes anything
• not that this makes any difference

The best English version depends on context. The French structure is idiomatic, so it is better to translate the function of the phrase rather than force each word into an exact English equivalent.

French décider can sometimes be used without an explicit object when the context makes it clear:

• pour décider = in order to decide

The object may be understood from the situation, for example:

• decide what to choose
• decide between options
• decide what to do

So the sentence does not need to spell out the object if it is already obvious from the context of comparing things.

Yes. Afin de décider would also mean in order to decide, but it is more formal than pour décider.

Compare:

• pour décider = normal, common
• afin de décider = more formal, more explicitly purposive

Since the sentence already has a somewhat formal tone, afin de décider would be possible, but pour décider is simpler and more common.