many?

class Person < ActiveRecord::Base
  has_many :pets
end

person.pets.count # => 1
person.pets.many? # => false

person.pets << Pet.new(name: 'Snoopy')
person.pets.count # => 2
person.pets.many? # => true

person.pets
# => [
#      #<Pet name: "Gorby", group: "cats">,
#      #<Pet name: "Puff", group: "cats">,
#      #<Pet name: "Snoop", group: "dogs">
#    ]

person.pets.many? do |pet|
  pet.group == 'dogs'
end
# => false

person.pets.many? do |pet|
  pet.group == 'cats'
end
# => true