body: Poole, Shaw-Mellors. [*Contract Law Concentrate* (4 ed 2019)](https://www.amazon.co.uk/Contract-Law-Concentrate-Jill-Pool/dp/0198840446/ref=dp_ob_title_bk). p 5.
  
  
  
  > 
  > The key distinction: bilateral and unilateral agreements
  > ========================================================
  > 
  > 
  > Broadly, agreements will be one of two types:
  >  • bilateral
  >  • unilateral.
  > 
  > 
  > Definition
  > ----------
  > 
  > 
  > **Bilateral agreements:** by far the most common in practice and consist of a promise in
  >  exchange for a promise. Bilateral means both parties are bound on the exchange of promises,
  >  although there has yet to be any performance of those promises.  
  > 
  >        A typical sale of goods agreement is bilateral. 
  > 
  > 
  > ### Practical example 1
  > 
  > 
  > Alex offers (or promises) to sell his bicycle to Becky for £150 and Becky accepts, thereby promising
  >  to pay £150. (We will use this as our example of a bilateral agreement and look at variations and additions
  >  to the facts throughout this chapter.)
  > 
  > 
  > Definition
  > ----------
  > 
  > 
  > **Unilateral agreements:** consist of a promise in exchange for an act. It follows that only one party is
  >  bound at the outset by a promise. The other’s acceptance is the performance of the requested act.  
  > 
  >        For example, a typical unilateral agreement will involve an offer of a reward and may be
  >  phrased as an ‘if’ contract: I promise to pay £50 to anyone who finds and returns my lost dog.
  > 
  > 
  > ### Practical example 2
  > 
  > 
  > Daniel offers (or promises) a free watch to anyone who returns three tokens from the packets of
  >  cereal he manufactures, together with a cheque for £5. Emily accepts by returning the three tokens
  >  with her cheque for £5. (We will use this as our example of a unilateral agreement and return to this
  >  example later in the chapter.)
  > 
  > 
  > 
  
  
  p 6.
  
  
  
  > 
  > Making the correct distinction.
  > -------------------------------
  > 
  > 
  > It is not possible to accept a unilateral offer by promising to
  >  find and return the lost dog or by promising to collect and return the tokens and the cheque. By
  >  comparison, the agreement to sell the bicycle cannot be unilateral. Students sometimes suggest
  >  that a simple sale contract is unilateral by interpreting the act of paying for the bicycle as the
  >  requested act. This is incorrect since, as long as it is possible to accept by promising to buy (which
  >  it is in the example), the agreement will be bilateral.
  > 
  > 
  > 
  
  
  I don't fathom what's "incorrect" about "interpreting the act of paying for the bicycle as the
  requested act". In the end Alex will require £150 from Becky, not just Becky's promise to pay £150. 
  
  
  I agree Becky promised to buy the bike for £150, but at some point she must pay the £150. She can't just keep promising to buy for £150 without paying the £150! 
  
  
  
title: Why isn't a simple sales contract unilateral?