The Spread of Nuclear Weapons: More may be better

Nuclear weapons have several effects on arms races.

1, there is no need for conventional arms races, any number of conventional weapons can be balanced by nuclear weapons. There is little point in having a ‘relative advantage’ in conventional weapons when there are nuclear weapons as a last resort.

2, nuclear arms races are almost as pointless, unless the possibility of achieving a first strike capability is within striking distance then it won’t matter if there is a big gap in the number of nuclear weapons two states have. Britain and France felt that their modest nuclear stockpiles were an effective deterrent to the USSR, and China felt its 40 or so nuclear weapons was enough when it was not firmly tied to one bloc.
[[Kenneth Waltz, “The Spread of Nuclear Weapons: More May Better,” Adelphi Papers, Number 171 (London: International Institute for Strategic Studies, 1981) http://www.mtholyoke.edu/acad/intrel/waltz1.htm]]

Arms races are reduced by arms control agreements and more trust between states, not caused by the weapons themselves, they are caused by insecurity a spread of nuclear weapons.  
 
Arms races are not between states. That is, one country feels insecure vis-a-vis another, so it ensures it has more nukes and conventional weapons than the other. Then the other country does it and so on, causing more and more tension and insecurity between the countries. Even when the number and sophistication of their weapons is almost par, they still attempt to develop further technological advances and a greater number of weapons than their foe.

This is why arms races occur - insecurity between states. It is not the inferiority/superiority in sophistication and numbers of nuclear weapons themselves that cause arms races - it is hostile relations between states that lead them to attempt to acquire more nuclear or conventional weapons than their neighbours.

The statement that 'there is little point in having a ‘relative advantage’ in conventional weapons when there are nuclear weapons as a last resort' is absurd. Relative advantage in conventional capabilities over your foes is essential for strategic success. Nuclear weapons have only been used in the most extreme of circumstances against one country in the past and are certainly not being considered as a viable option even 'as a last resort', except maybe by Kim Jong Il. This is why conventional superiority is so important in today's age. We all breathed a sigh of relief when the Cold War ended and this notion was debunked, and the world committed itself to reducing the numbers of nuclear weapons and began signing confidence-generating arms control agreements.  
 
 
Also, the statement that 'any number of conventional weapons can be balanced by nuclear weapons' is hugely unlikely. agreements.  
 
I cannot flummox the possibility that a country like Pakistan would feel comfortable with having 1000 nuclear weapons and only a tenth of India's conventional weapon capabilities. This is just impossible because although Pakistan has a 'first use' nuclear weapons doctrine, in the event of India conducting military excercises on its' border they would be unable to drop a nuclear weapon on Mumbai because this is disproportionate - while also they would not be able to threaten India credibly because Indian leaders know they would not retaliate with nuclear weapons and their conventional capability would be too disproportionate to credibly threaten India's troops to withdraw.
By building up huge amounts of nukes and leaving yourself with little conventional capability is not at all prudent.