Mi padre dice que no es que la filosofía sea inútil, es que la biología le parece más práctica.

to be

Breakdown of Mi padre dice que no es que la filosofía sea inútil, es que la biología le parece más práctica.

• mi: my
• que: that
• más: more

Questions & Answers about Mi padre dice que no es que la filosofía sea inútil, es que la biología le parece más práctica.

Why does the sentence use no es que la filosofía sea inútil instead of just la filosofía no es inútil?

The structure no es que + subjunctive is a special pattern in Spanish used to:

• Deny or downplay an explanation, and
• Introduce a more accurate explanation afterwards.

So:

• La filosofía no es inútil.
  = A straightforward statement: Philosophy is not useless.

• No es que la filosofía sea inútil, es que la biología le parece más práctica.
  = It’s not that philosophy is useless; it’s that biology seems more practical to him.

The no es que… part suggests “that’s not really the issue / that’s not exactly the reason,” and prepares the listener for the real reason in the second part of the sentence.

Why is it sea and not es in no es que la filosofía sea inútil?

Because this is the subjunctive after the fixed expression no es que….

• After no es que, Spanish normally uses the subjunctive to talk about a situation that is:
  • being rejected as the true cause, or
  • presented as hypothetical / not asserted as plain fact.

So:

• Es que la filosofía es inútil. (indicative: es)
  = The issue is that philosophy is useless. (speaker presents it as fact)

• No es que la filosofía sea inútil. (subjunctive: sea)
  = It’s not that philosophy is useless. (the speaker rejects this as the real explanation)

Replacing sea with es here would sound ungrammatical to a native speaker in this structure.