Pascal pointed out that the arguments for and against the reality of God – or, more fundamentally, whether that there was any point to “life the Universe and Everything” – were not fairly balanced, in the complete absence of any evidence one way or the other.
Following Plato’s account of Socrates’ argument, Pascal observed that either there was a purpose to life or there wasn’t. Moreover, one could either live one’s life as if there was a point to it all or as if there was no such point. Now, if there is in fact no point to life it doesn’t matter at all how one lives – because there is no significance in anything whatever. On the contrary, if there is in fact a point to life it behoves us to attempt to discover it and to do our best to live according to our best appreciation of whatever the significance and purpose of life might be.
Hence, whether or not life has any value, significance or rationale it makes sense to act as if it does. This is because if life has no purpose one has nothing to lose by living as if it did have one (even though one is wrong!) whereas if it does have a rationale one has very much to gain: in potential, the attainment of that value and the fulfilment of the purpose of life. Hence the rational person is compelled by their rationality to act as if life has value and is purposeful, and to seek out – as well they may – what that value and purpose might be. There is no possible motive for acting otherwise and to do so would be irrational and imprudent.
Moreover, there cannot exist any valid argument or evidence against the proposition that existence is significant. This is because if there were such a valid argument or evidence then that argument or evidence at least would have significance, meaning and some kind of value; but this possibility is excluded by the supposed conclusion of the argument itself, namely “Life the Universe and Everything are devoid of value and significance.”
Furthermore, this statement is incoherent, for if it were true it would be of huge significance and so contradict itself. So if one is going to be rational one must adopt its negation; which amounts to the statement “there is, of necessity, some significance to be found in Life the Universe and Everything.” The astute reader will recognise here a version of the Ontological Argument; where rationality itself here gives rise to the necessity of value and significance rather than “The Greatest Conceivable Being.”
Of course, neither Pascal’s Wager nor the version of the Ontological Argument which it implies directly addresses the reality of God. However, once one recognises that God is identical with the basis of value (“The Good”, as Plato names this) then there is little to be chosen between the statements “God is real” and “Being has significance.”
 Plato reports Socrates arguing that it makes sense to believe that there is a good life after bodily death. He observes that either this hope is true, in which case one should live one’s mortal life preparing for the blessed eternity which follows; or else it is false, and one might as well act according to the same (misguided) hope: because at least then one will live without fear and be of good cheer. See “Phaedo” (91a-b)
 Pensées (1670). Pascal actually worded his argument in terms of personal benefit and happiness. His version of the argument can, therefore, be construed as recommending the sacrifice of personal integrity for the sake of selfish gratification; but I do not believe this to have been Pascal’s intent. Pascal conceived his wager as a response to his quasi-Calvinist conviction (contrary to the work of Plato, Anselm, Aquinas and Descartes) that human reason was incapable of proving the reality of God.
 This purpose might be no more than hedonistic pleasure; in which case the fact that it is rational to live life as if it had significance would not force any-one to behave in a responsible or sober manner. However, people typically find that the pursuit of pleasure or fun or excitement as goals in their own right is ultimately unsatisfying. This is because these good things are in fact not the ultimate good, but at best contributors to and indicators of that good.
 It could be argued that if everything is pointless, then even this proposition is pointless and while it seems to have a significance this is no more than a delusion. However, if this is the case, how does it come to be the case that the contention is being pressed that “life is devoid of significance”? It would seem that the idea that anyone would bother to argue this case is incompatible with the case which they are supposed to be arguing for!