I'l start with one of my old philosophy assignments on The Intuition Thesis.
‘Intuition and Deduction can only give us information of propositions that are concerned with the relations of our concepts.’ Discuss.
In this essay it will be argued that, despite strong rationalist arguments providing evidence to the contrary, intuition and deduction can only provide us information with regards to the relations of our concepts.
‘The Intuition/Deduction Thesis’ claims that we can know some propositions by intuition and still more by deduction. Empiricists are willing to accept the thesis so long as it is restricted to propositions solely about the relations between our own concepts. For example philosophers from different groups can agree that we can know by ‘intuition’ that our concept of God includes our concept of eternal existence. They agree that just by examining the concepts involved we can grasp that one includes the other, in this case ‘God’ and ‘eternal existence’. Where Rationalists and Empiricists disagree on this subject is where the former assert that intuition and deduction can tell us about matters of fact (i.e. propositions that contain substantive information about the world) and the latter deny this.
Descartes claims that knowledge requires certainty and that certainty is beyond what empirical evidence of the world can provide. He states we can never be sure that our sensory impressions are not simply part of a dream or massive demon orchestrated deception. To Descartes only intuition and deduction provide the certainty needed for knowledge, and given that we have some substantive knowledge of the world, the intuition thesis must be true. He argues that “all knowledge is certain and evident cognition” and when we “review all the actions of the intellect by means of which we are able to arrive at a knowledge of things with no fear of being mistaken” we “recognise only two; intuition and deduction”. Essentially Descartes defends the view that intuition and deduction can tell us information of the wider world by assuming that we already know some substantive external world truths, then adds analysis of what knowledge (in his view) requires. Finally, he then concludes that that our knowledge must result from intuition and deduction. This is a less than compelling argument. Firstly Descartes’ assumption that that knowledge requires certainty is difficult to defend as it rules out much of what we commonly take ourselves to know in the regular course of events. Naturally often our knowledge is incorrect and we are misinformed. After all it has previously been considered good knowledge that the Earth was at the centre of the galaxy and that all the planets revolved around it. Secondly, intuition is not always a source of certain knowledge. Could it not be that we should doubt our intuitions as well as our sense impressions? For all we know an evil demon deceiver might also cause us to intuit false propositions. However Descartes argues that we can know with certainty that no such deceiver interferes with our intuitions and deductions. He states they are infallible as God guarantees their truth.
Leibniz provides us with a more plausible argument to prove the Intuition/Deduction thesis can provide information of the wider world. Leibniz describes how the senses although necessary for all knowledge are not sufficient to give us the whole of it, this is because they never give us anything but ‘instances’ , particular individual truths. He states even if we experience many individual instances which appear to confirm a general truth it is still not enough to establish the universality of the that truth. This is because it doesn’t follow that what happened once will happen the same way again, so it appears that necessary truths (irrefutable truths) such as we find in pure maths must have principals whose proof does not depend on individual instances. Consequently no part of the testimony of the proof resides with the senses or experience and so the best explanation of this knowledge is intuition and deduction. Leibniz also mentions logic, metaphysics and morals as other areas where our knowledge outstrips our experience and so provides the basis for an appeal to intuition. Judgements in morals involve a form of obligation or value that lies beyond experience, which only informs us about what is that case rather than what it ought to be.
The strength of this argument varies with its examples of supposed knowledge however I will focus on the claims of knowledge known by intuition in the fields of mathematics and morals. We know a great deal of mathematics and what we know, we know to be necessarily true. None of our experience warrants a belief in such necessity, and we do not seem to base our logic on any experiences. The warrant that provides us with knowledge arises form an intellectual grasp of the propositions which is clearly part of our learning. Similarly we seem to have moral knowledge that all beings are equal and that pleasure is inherently good. However Hume argues that knowledge of the necessary truths of mathematics is not to be considered substantive knowledge of the world. He states all the objects of human inquiry or reason are divided into ‘Relations of Ideas’ and ‘Matters of Fact’ and that states that mathematics falls under the former. Propositions that involve ‘relations of ideas’ are discoverable by the mere operation of thought alone and Hume states that knowledge of maths is simply knowledge of the relations of our own ideas. In concern of morals Hume offers an analysis of our moral concepts in which he finds this knowledge to be empirically gained and therefore not known by intuition or deduction. Furthermore A.J Ayer in his assigning of every cognitively meaningful sentence one of two categories (essentially either analytic or synthetic) and cuts out and leaves no room for any meaningful knowledge of the external world to be known by intuition or deduction. He states there can be no meaningful knowledge of the world known by intuition or deduction because knowledge of this sort is valid independent of experience and thus lacks any factual content. This in turn means it cannot be verified or falsified and propositions of this nature are factually meaningless to Ayer. The rationalists’ argument for the Intuition/ Deduction Thesis goes awry at the start, according to the empiricists; by assuming we can have substantive knowledge of the external world that outstrips what experience can warrant. We cannot.
We have seen strong rationalist arguments providing evidence that we can know truths of morals, mathematics and metaphysics by intuition and deduction. Despite this I am inclined to side with the empiricist counter arguments on these points and conclude as a result that induction and deduction can only provide us information with regards to the relations of our concepts.