I'm not sure that philosophical coherence is essential or even possible these days. In order to achieve that parties would need to have a support base whose interests are well-aligned and large enough to form an electoral majority.
In the old days the major parties could have coherent philosophies because politics was based essentially on economic class. The party of the left represented the working class (manual workers), while the party of the right represented the middle and upper classes (business people, professionals and land-owners). Cultural issues were less important because both sides accepted the predominance of Christianity, patriarchy, heterosexuality and whiteness. This seems no longer tenable because of economic and social changes.
The Republican party started playing the race card around 50 years ago because it realised that it could no longer rely on traditional free market conservatism to win electoral majorities, as the middle class became more educated and more liberal. In order to appeal to white working class voters it emphasised 'culture war' issues to distract attention from its primary agenda of advancing the interests of the well-off. This started well before Trump; he has just taken it further.
The obvious tension is that if the working class continue to struggle when Republicans are in power they might realise that their economic interests are not being served. So far they have been able to offset this by further ramping up the culture wars and appealing to blue collar workers through protectionism, anti-immigrant policies and opposing environment policies affecting their industries.
The Democrats, on the other hand, have seen their traditional support base eroded though shifts in the economy away from highly-unionised blue collar jobs in manufacturing etc. They have attempted to compensate by broadening their appeal to minorities and socially-progressive educated urban voters. This has created tensions that have contributed to white working class voters drifting toward the Republicans.
The centre-left policy agenda over the past 30 years has been to accept a largely deregulated globalised economy, while supporting relatively moderate policy interventions to ameliorate its excesses. Regardless of the result in November I tend to agree that playing safe and hoping to benefit from the other side's excesses and mistakes will not suffice going forward. The right time for a policy rethink would have been after the 2016 election loss. Unfortunately, the US system, where the opposition party does not even have a leader until the election year, does not seem to lend itself to this.