Here the notion of causality is one of contributory causality as discussed above: If the true value 
  
    
      
        
          a
          
            j
          
        
        ≠
        0
      
    
    {\displaystyle a_{j}\neq 0}
  , then a change in 
  
    
      
        
          x
          
            j
          
        
      
    
    {\displaystyle x_{j}}
   will result in a change in y unless some other causative variable(s), either included in the regression or implicit in the error term, change in such a way as to exactly offset its effect; thus a change in 
  
    
      
        
          x
          
            j
          
        
      
    
    {\displaystyle x_{j}}
   is not sufficient to change y.
Aristotle further discerned two modes of causation: proper (prior) causation and accidental (chance) causation. All causes, proper and accidental, can be spoken as potential or as actual, particular or generic. The same language refers to the effects of causes, so that generic effects are assigned to generic causes, particular effects to particular causes, and actual effects to operating causes. Averting infinite regress, Aristotle inferred the first mover—an unmoved mover. The first movers motion, too, must have been caused, but, being an unmoved mover, must have moved only toward a particular goal or desire. Pyrrhonism
While the plausibility of causality was accepted in Pyrrhonism, it was equally accepted that it was plausible that nothing was the cause of anything. Middle Ages
In line with Aristotelian cosmology, Thomas Aquinas posed a hierarchy prioritizing Aristotles four causes: "final > efficient > material > formal". Aquinas sought to identify the first efficient cause—now simply first cause—as everyone would agree, said Aquinas, to call it God. Later in the Middle Ages, many scholars conceded that the first cause was God, but explained that many earthly events occur within Gods design or plan, and thereby scholars sought freedom to investigate the numerous secondary causes. After the Middle Ages
For Aristotelian philosophy before Aquinas, the word cause had a broad meaning. It meant answer to a why question or explanation, and Aristotelian scholars recognized four kinds of such answers. With the end of the Middle Ages, in many philosophical usages, the meaning of the word cause narrowed.