past or present subjunctive

Question

Which subjuntive do you se with the present perfect indicative, the past subjunctive, or the present subjunctive? For example, how would you say, you have allowed him to corrupt your mind, using the subjunctive?

Answer 1

clipped from grammar article (other rules don't involve present perfect tense)

If the main verb is in the present, future, or present perfect tense or the imperative mood, and the dependent (subjunctive) verb refers to action that takes place (whether in actuality or not) at the same time or after the main verb, then the dependent verb should be in the present subjunctive. Example: Espero que comas. (I expect you to eat.)

If the main verb is in the present, future or present perfect tense or imperative mood, and the dependent (subjunctive) verb refers to action that has been completed (whether in actuality or not), then the dependent verb should be in the present perfect subjunctive. Example: Espero que hayas comido. (I expect you to have eaten.)

Unfortunately neither of the examples used the present perfect tense in the main clause, but the rule still applies.

As you may notice your original question is flawed. The choice is not between the present and the past subjunctive. If you are interested in when you use the past (imperfect subjunctive/pluperfect subjunctive) look at the other rules in the article.

Answer 2

Basically, both parts of the sentence should be in the same tense; it doesn't make sense to use subjunctive otherwise. Generally, you can reason your way through what tense it should be.

"Has dejado que él conagió tu mente." - This can't be in subjunctive because the event has already happened; we are talking about something real.

"No quiero que lo dejes contagiar tu mente." - This hasn't happened, so you use subjunctive.

"No creía que él había contagiado tu mente." - Both clauses are in the past.

This cannot exist grammatically and logically: "No creo que contagiara tu mente."