Spanish term (edited): por m�todo exclusivamente

or "not by means of the method exclusively", or "not simply guided by the method".

It refers to Descartes because his philosophical inquiry was strictly guided by methodological procedures, leaving the object of the inquiry to be "determined" somehow by the manner in which the philosopher has to shape her or his inquiry in the first place. The truth cannot be simply determined by the object itself, but by subject and, more importantly, by the way in which the philosopher enquires into that object.
What the text above is saying is the opposite, more or less. From the sceptic's point of view, Truth cannot be comprehended (if it existes at all!), and all we have left is to let the object disclose itself gradually by its own means. Scepticism is tied to empiricism (truth lies out there, in the object itself), whereas Descartes is a racionalist who claims that the truth resides in the way in which objects are disclosed in human consciousness (but not in human consciousness itself). That's why the method is so important for him.
Hope this helps.
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Note added at 1 hr 15 mins (2005-05-24 09:57:59 GMT)
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The explanation would also apply to moral philosophy. We do not take moral decisions depending on the formal/methodological paths that the inquiry itself has set up, but by how things turn up to be. given that we are talking about scepticism, and truth does not count, then morality cannot be based on any sort of moral law, or principle of action, but must remain constantly open ...In fact, it is saying that there is no morality, because there is no truth, there is no good nor evil. Take things as they come, and act as you think you should in that particular moment. As you can see, the level of moral responsibility is more than low for the sceptics.