Do you know the sun will rise tomorrow?

University Degree Historical and Philosophical studies

Hannah Cleaver

Do you know that the sun will rise tomorrow?

This question in itself is very confusing, as we as human beings assume that the sun will rise as it is inherently in our nature to do so. My aims are to discuss the implications of this, ask why exactly it is that we make this assumption, and to discuss the responses and interpretations that philosophers would have had to this question. Firstly Hume introduces the problem of induction to us, and with this he proves that it is never possible to know whether the sun will rise. Descartes makes a contrasting point when he investigates the nature of the human mind, and therefore the world around us, and in his conclusion he reasons that we know that the sun will rise tomorrow as God exists. I will go into detail about his argument and reasoning here, although I personally believe that it has vital flaws. I intend to prove that Hume has the necessary argument to the question, “Do you know that the sun will rise tomorrow”?, in that we can never know for certain; yet there is no reason for us to doubt that it will or else our lives would be plagued by worry and fear.

Hume and the problem of induction

Induction has been around for centuries, and it is Hume who first initiates this debate. Induction itself is to do with human nature and the way we live in the world around us. If we do something once with an outcome, and then several times again with the same outcome, we then develop our own conclusion that in the future whenever we do the first thing, that same thing will follow. For example when we have, in the past, sat on a chair, it supports our weight and never lets us fall onto the floor. Therefore we conclude that in the future, when we sit on a chair, it will always support our weight. This is the basis for how we learn as we grow up in the world, using our instincts and cognitive reasoning to understand everything around us and how it works. When we walk, we never think that the ground will not support our weight unless there are some unusual circumstances that indicate so, for example cracks in the ground around us or warning signs. Nature has appeared to be uniform, and it is this uniformity that has allowed us to continue reasoning in this way without serious fault.

This is a preview of the whole essay

Unfortunately, we have no justification to this method of reasoning. In a deductive argument if you negate the conclusion it provides a contradiction, yet in the matter of inductive reasoning, this is not the case. For if you conclude that when we sit on a chair it will not support our weight, it is still an entirely reasonable conclusion and does not provide a contradiction. Hume highlights this himself with “The contrary of every matter fact is still possible; because it can never imply a contradiction, and is conceived by the mind with the same faculty and distinctness, as if ever so conformable to reality”. We cannot use inductive reasoning to justify our conclusions either. You can reason that the past is like the future because the past pasts have been like the past futures; as nature is uniform we can think this way. But we only know that nature is uniform because it has been in the past, and this is using induction to justify our argument; therefore it is circular. There have been other attempts to justify induction, such as using probability to explain our conclusions. However in using probability how are we ever certain of the future? For only a probability of ‘1’ denotes absolute certainty and this is never the case in the world. There are always exceptions where a chair has not supported our weight, and although this makes you initially cautious you eventually dismiss the idea as an exception to the rule and continue to assume as before. This would give a probability of ‘0.9’ or thereabouts, but you never think that way when assessing a chair, you just sit on it and are confident it will not collapse.

Yet, when we consider the fact that our reasoning cannot be justified, it still seems alien for us to think otherwise. There is no conceivable way to live without using induction in our every day life. We would otherwise be consumed by fear about the world around us, as none of our assumptions can be justified. Science itself is based on induction: “observations made in a variety of circumstances are to be recorded impartially and then induction is used to arrive at a general law”. Hume takes the problem of induction yet does not provide a valid explanation or justification of it. He simply says that inductive reasoning is how our mind has been developed to work, as it has allowed us to live so far prosperously; there is no reason for us to stop. The actual concept of not thinking inductively is ridiculous; there isn’t a way of life, of which we know of, without induction.

Hume states “As nature has taught us the use of our limbs, without giving us the knowledge of the muscles and nerves, by which they are actuated; so has she implanted in us an instinct, which carries forward the thought in a correspondent course to that which she has established among external objects; though we are ignorant of those powers and forces, on which this regular course and succession of objects totally depends” (p130). Hence we have been made to think this way that we do, without knowing the underlying causes or concepts to which we do so, yet it provides us instinctively with an insight into the world. As this is so, we have no reason to doubt it and therefore can be quite certain in stating that the sun will rise tomorrow.

Descartes, God, and the existence of the external world

Descartes begins his mediations with sceptical doubt about the world, the mind, and everything associated with them. Within the meditations he proves the existence of the mind and from this the fact that God must exist. He uses “clear and distinct” perceptions that are known a priori; they are ideas that are distinct to the external world and therefore must be true, because they could not be falsified by any external influences. To prove the existence of God he uses these clear and distinct perceptions of the idea of God that he has in his mind. As God is not in the world around us these must be separate and distinct ideas and therefore true. Descartes takes this further to say that because God exists, everything in the external world is therefore able to be replied upon and all clear and distinct ideas cannot be false. For God by definition is not a deceiver, and would never let us believe something that is undoubtedly false. From this you can say that the sun will rise tomorrow, because God would never deceive us and make what had previously been certain thrown into doubt.

Unfortunately I find a big flaw in Descartes argument for the existence of God, which therefore throws doubt upon the certainty that the sun will rise tomorrow. He uses clear and distinct perceptions, which he knows without any other influence except his own mind, to explain the existence of God. Then, from this, he says that because God exists, his clear and distinct perceptions must be true. Yet how can they not be true if he already relied on them to prove the existence of God? Descartes uses one of his premises in his argument as the conclusion for his argument, which achieves nothing; if you do not believe the premise you will never believe his conclusion in the existence of the external world. Descartes argument is therefore circular.

If we do not believe in God, and are not persuaded by Descartes’ argument for the existence of God, how can we say that we know that the sun will rise tomorrow? I cannot be persuaded by Descartes’ argument, even considering any evidence that would suggest why his argument may not be circular. A way out of his Cartesian circle is to say that the clear and distinct perceptions that Descartes’ thought in the first instance, like the idea of God, were separate to all clear and distinct perceptions in general that are proved after God’s existence. But I find this idea of the distinction between the two types of perception very hazy, and it is not actually defined by Descartes himself in his mediations. This is just an interpretation of Descartes’ meditations and to me that is not enough justification to be persuaded in the existence of God.

Why we can never know if the sun will rise tomorrow, but assume it will

From both of these different perspectives, I can see the doubts and reasons why neither of them can establish that the sun will rise or that it won’t. Hume believes that the sun will rise, even though we still have yet to find justification in the inductive reasoning. Descartes would also say that the sun would rise tomorrow as God exists therefore it must be so. I have explained why I cannot be persuaded by Descartes argument, as its nature is to be circular. Therefore I think that we can never be certain that the sun will rise tomorrow, as our inductive reasoning can never suitably be justified. However, Hume’s answer is the clearest and most reasonable to take on. We do not necessarily know the exact means to why we think inductively, but as we have been created this way and we do not yet have a cause to doubt its ability, there is no reason to live in fear and worry of every aspect of our lives; we can quite happily assume that the sun will rise tomorrow.

Bibliography

Hume, ‘Sceptical doubts concerning the operations of the understanding’ and ‘Sceptical solution of these doubts’, An Enquiry concerning Human Understanding, (Oxford University Press, 1999)

Descartes, ‘Third Meditation’, Meditations on First Philosophy, (Cambridge University Press, 1996)

Hume, ‘Sceptical doubts concerning the operations of the understanding’, Section 4 of An Enquiry Concerning Human Understanding (Oxford University Press, 1999) p. 108. All further references to this edition are stated in the text.

James Ladyman, ‘The Problem of induction and other problems with inductivism’, Chapter 2 of Understanding Philosophy of Science (London, Routledge, 2002) p. 31

Descartes, ‘Third Meditation’, Meditations on First Philosophy, (Cambridge University Press, 1996) p. 30