He was speaking on a radio programme ahead of the Democratic Party’s special meeting, where members will vote on whether the party will field candidates in the Legislative Council polls in December.
Tong said it was the “civic duty” of political parties to reflect their supporters’ views in the legislature.
“I think a political party exists for the purpose of gaining seats in any assembly or legislature to voice their supporters’ views. This of course is founded on the basis that you accept the constitutional system,” he said.
“If you don’t accept the constitutional system or the election system and you say that so long as this particular system was to exist then I won’t join the election… I don’t really see the purpose of their existence or why they should call themselves a political party.”
He noted that some members of the think tank he founded, Path of Democracy, were keen to join the upcoming Legco election.
He said the group would decide whether to go ahead after assessing their chances of winning.