After a discussion about the "difficulties to distinguish knowledge from faith" someone replied to me that the quote implies faith because it uses the word "think". But as it is generally understood:
As Descartes explained, "We cannot doubt of our existence while we doubt." A fuller form, dubito, ergo cogito, ergo sum ("I doubt, therefore I think, therefore I am”), aptly captures Descartes’ intent.
The quote is used by Descartes so to define secure knowledge.
This proposition became a fundamental element of Western philosophy, as it purported to form a secure foundation for knowledge in the face of radical doubt.
This "I am means i securely know that i exist.
In Principles of Philosophy Descartes's notes:
Latin: "Non posse à nobis dubitari, quin existamus dum dubitamus: at que hoc esse primum quod ordine philosophando cognoscimus."
English: "That we cannot doubt of our existence while we doubt, and that this is the first knowledge we acquire when we philosophize in order."
The proposition is sometimes given as dubito, ergo cogito, ergo sum. This fuller form was penned by the eloquent French literary critic, Antoine Léonard Thomas, in an award-winning 1765 essay in praise of Descartes, where it appeared as "Puisque je doute, je pense; puisque je pense, j'existe." In English, this is "Since I doubt, I think; since I think I exist"; with rearrangement and compaction, "I doubt, therefore I think, therefore I am", or in Latin, "dubito, ergo cogito, ergo sum".
A further expansion, dubito, ergo cogito, ergo sum—res cogitans ("…—a thinking thing") extends the cogito with Descartes's statement in the subsequent Meditation, "I am a thinking (conscious) thing, that is, a being who doubts, affirms, denies, knows a few objects, and is ignorant of many …". This has been referred to as "the expanded cogito".
So the question is what is the consensus about this argument regarding secure knowledge? As i know all major philosophical doctrines espouse it (including idealism of all forms, materialism) and only radical skepticism and poor empiricism tries to attack it.