Editing Rationalism (section)

===Intuition/deduction thesis===
{{Main|Intuition (philosophy)|Deductive reasoning}}

{{Blockquote|text=''"Some propositions in a particular subject area, S, are knowable by us by intuition alone; still others are knowable by being deduced from intuited propositions."''<ref name="The Intuition/Deduction Thesis">Stanford Encyclopedia of Philosophy, [http://plato.stanford.edu/entries/rationalism-empiricism/#2 The Intuition/Deduction Thesis] {{Webarchive|url=https://web.archive.org/web/20180929143915/http://plato.stanford.edu/entries/rationalism-empiricism/#2 |date=2018-09-29 }} First published August 19, 2004; substantive revision March 31, 2013 cited on May 20, 2013.</ref>}}

Generally speaking, intuition is [[A priori and a posteriori|''a priori'']] knowledge or experiential belief characterized by its immediacy; a form of rational insight. We simply "see" something in such a way as to give us a warranted belief. Beyond that, the nature of intuition is hotly debated. In the same way, generally speaking, deduction is the process of [[reasoning]] from one or more general [[premise]]s to reach a logically certain conclusion. Using valid [[argument]]s, we can deduce from intuited premises.

For example, when we combine both concepts, we can intuit that the number three is prime and that it is greater than two. We then deduce from this knowledge that there is a prime number greater than two. Thus, it can be said that intuition and deduction combined to provide us with ''a priori'' knowledge{{snd}}we gained this knowledge independently of sense experience.

To argue in favor of this thesis, [[Gottfried Wilhelm Leibniz]], a prominent German philosopher, says,

{{Blockquote|text=The senses, although they are necessary for all our actual knowledge, are not sufficient to give us the whole of it, since the senses never give anything but instances, that is to say particular or individual truths. Now all the instances which confirm a general truth, however numerous they may be, are not sufficient to establish the universal necessity of this same truth, for it does not follow that what happened before will happen in the same way again. … From which it appears that necessary truths, such as we find in pure mathematics, and particularly in arithmetic and geometry, must have principles whose proof does not depend on instances, nor consequently on the testimony of the senses, although without the senses it would never have occurred to us to think of them…<ref>Gottfried Wilhelm Leibniz, 1704, ''New Essays on Human Understanding'', Preface, pp. 150–151.</ref>}}

Empiricists such as [[David Hume]] have been willing to accept this thesis for describing the relationships among our own concepts.<ref name="The Intuition/Deduction Thesis"/> In this sense, empiricists argue that we are allowed to intuit and deduce truths from knowledge that has been obtained [[A priori and a posteriori|''a posteriori'']].

By injecting different subjects into the Intuition/Deduction thesis, we are able to generate different arguments. Most rationalists agree [[mathematics]] is knowable by applying the intuition and deduction. Some go further to include [[Ethics|ethical truths]] into the category of things knowable by intuition and deduction. Furthermore, some rationalists also claim [[metaphysics]] is knowable in this thesis. Naturally, the more subjects the rationalists claim to be knowable by the Intuition/Deduction thesis, the more certain they are of their warranted beliefs, and the more strictly they adhere to the infallibility of intuition, the more controversial their truths or claims and the more radical their rationalism.<ref name="The Intuition/Deduction Thesis"/>

In addition to different subjects, rationalists sometimes vary the strength of their claims by adjusting their understanding of the warrant. Some rationalists understand warranted beliefs to be beyond even the slightest doubt; others are more conservative and understand the warrant to be belief beyond a reasonable doubt.

Rationalists also have different understanding and claims involving the connection between intuition and truth. Some rationalists claim that intuition is infallible and that anything we intuit to be true is as such. More contemporary rationalists accept that intuition is not always a source of certain knowledge{{snd}}thus allowing for the possibility of a deceiver who might cause the rationalist to intuit a false proposition in the same way a third party could cause the rationalist to have perceptions of [[nonexistent object]]s.