Jansenius: free choice remains, but freedom for true good is lost; the sinner can only sin
Jansenius does grant that after sin there remained in man the faculty called free choice, by which we will and act rightly or wrongly; which, just as it is now of itself inclined to evil, can also be bent to good by grace and embrace it freely.
Yet he maintains, following Augustine and the truth of the matter, that the freedom of choice with respect to true and saving good can rightly be said to have been destroyed and lost in man through sin. Sin has not stripped man of the freedom essential to the will, which is opposed to compulsion and to determination by nature. What perished entirely in man through sin is the freedom for good that is opposed to bondage, until man's will is set free by the grace of Christ the Saviour.
In his view, sin has made man such a slave of sin that whatever he does, he can no longer do anything but sin. He can indeed refrain from particular sins, but when he refrains from one he falls into another and trades sin for sin, not for true acts of virtue.
For his will, turned from God by a perverse affection and seeking its good in creatures, always and everywhere strays from the true end until God's grace lifts it up, and so whatever it does cannot be free of sin. This is set out at length by that author in his book on the grace of the first man, chapters 6 and 7, in On the State of Fallen Nature, book 2, likewise chapters 6 and 7, and in many other places.
Latin
XVII. Caeterum Jansenius agnoscit quidem post peccatum in homine mansisse facultatem quae dicitur liberum arbitrium, & per quam recte aut perperam volumus & agimus, quaeque, ut jam ex se ad malum prona est, ita & per gratiam ad bonum flecti potest, illudque libere amplecti: sed tamen pertendit, secundum Augustinum, & rei veritatem, bono sensu dici posse libertatem arbitrii, respectu veri & salutaris boni, per peccatum in homine perditam & amissam esse. Non quod peccatum hominem spoliaverit ea libertate, quae voluntati essentialis est; & quae coactioni ac determinationi per naturam opponitur: sed quia prorsus per peccatum in homine periit libertas illa ad bonum quae opponitur servituti, donec per Christi salvatoris gratiam liberetur hominis voluntas. Nempe, ex ejus sententia, homo per peccatum sic est factus peccati servus, ut quicquid agat non amplius nisi peccare possit. Quoniam potest quidem a singulis peccatis abstinere; sed quum ab uno peccato abstinet, in aliud incidit, & peccatum peccato, non veris virtutis actibus commutat. Quippe cujus voluntas affectu pravo a Deo aversa, & bonum suum in creaturis quaerens, donec sursum per Dei gratiam attollatur, a vero fine semper & ubique aberrat, & ideo quicquid agat, peccato carere non potest, ut prolixe videre est apud authorem illum libro de gratia primi hominis cap. 6. & 7. & De statu naturae lapsae lib. 2. cap. item 6. & 7. & pluribus aliis in locis.