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¡¡¡¡the starting point for any analysis in finance involves assigning a cur-rent price to a future strearfi of uncertain payoffs£®this is the basic notionbehind any asset£®pricing model£®take for example£¬the price of a shareto a competitive firm£®since the share entitles the owner to claims for the future profits of the firm£®a central problem is to assign a value to thesefuture profits£®take another asset-a house£®this provides housing ser-vices in all states of nature and at all dates£®consequently£¬the value of thehouse today must reflect the value of these future services¡£other examplesinclude the pricing of durable goods or investment projects based on theirfuture expected marginal products.one approach to monetary economicsalso follows this basic principle-if money as an asset has value in equilib£¬rium£¨in the absence of any legal restrictions£©£¬then this value must reflectthe stream of services provided by this asset£® ¡¡¡¡our approach is to derive pricing relationships for different assets byspecilying the economic environment at the outset.ohe of the earliestexamples of this approach is merton¡²342¡³£®however£¬merton does notrelate the technological sources of uncertainty to the equilibrium prices ofthe riskv assets£®aiternatively£¬he assumes a given stochastic process for thereturns of different types of assets and then prices them given assumptionsabout consumer preferences£®consequently£¬the supply side is not explic.itly considered by merton£®the asset-pricing model of lucas¡²317¡³is fullygeneral equilibrium but it is an endowment economy£¬so that consumptionand investment decisions are trivial£®brock¡²76¡³develops an asset£®pricingmodel with both the demand and supply side fully specified and links itup to ross¡®s¡²369¡³arbitrage pricing model£® ¡¡¡¡in this book£¬we will start from an explicit economic environment anddeduce the implications for asset prices£¬and the form of the asset-pricingfulnction from the equilibrium in these environments£®to study the prob-lem of asset pricing£¬we couid also follow another approach£ºwe couldtake a very general and abstract approach£¬vmwlng asset pricing as thevaluation of a future stream of uncertain payoffs from the asset accord£®mg to a general pricing function£®£¨aiven a minimal set ot assumpnonsabout the set of payoffs£¬we could try to characterize the properties ofthis abstract pricing function£®